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Category Archives: Human Genetics

1st draft of a human ‘pangenome’ published, adding millions of …

Posted: May 17, 2023 at 12:13 am

Scientists have published the first human "pangenome" a full genetic sequence that incorporates genomes from not just one individual, but 47.

These 47 individuals hail from around the globe and thus vastly increase the diversity of the genomes represented in the sequence, compared to the previous full human genome sequence that scientists use as their reference for study. The first human genome sequence was released with some gaps in 2003 and only made "gapless" in 2022. If that first human genome is a simple linear string of genetic code, the new pangenome is a series of branching paths.

The ultimate goal of the Human Pangenome Reference Consortium, which published the first draft of the pangenome on Wednesday (May 10) in the journal Nature (opens in new tab), is to sequence at least 350 individuals from different populations around the world. Although 99.9% of the genome is the same from person to person, there is a lot of diversity found in that final 0.1%.

"Rather than using a single genome sequence as our coordinate system, we should instead have a representation that is based on the genomes of many different people so we can better capture genetic diversity in humans," Melissa Gymrek (opens in new tab), a genetics researcher at the University of California, San Diego, who was not involved in the project, told Live Science.

Related: More than 150 'made-from-scratch' genes are in the human genome. 2 are totally unique to us.

The first full human genome sequence was completed in 2003 by the Human Genome Project and was based on one person's DNA. Later, bits and pieces from about 20 other individuals were added, but 70% of the sequence scientists use to benchmark genetic variation still comes from a single person.

Geneticists use the reference genome as a guide when sequencing pieces of people's genetic codes, Arya Massarat (opens in new tab), a doctoral student in Gymrek's lab who co-authored an editorial about the new research with her in the journal Nature, told Live Science. They match the newly decoded DNA snippets to the reference to figure out how they fit within the genome as a whole. They also use the reference genome as a standard to pinpoint genetic variations different versions of genes that diverge from the reference that might be linked with health conditions.

But with a single reference mostly from one person, scientists have only a limited window of genetic diversity to study.

The first pangenome draft now doubles the number of large genome variants, known as structural variants, that scientists can detect, bringing them up to 18,000. These are places in the genome where large chunks have been deleted, inserted or rearranged. The new draft also adds 119 million new base pairs, meaning the paired "letters" that make up the DNA sequence, and 1,115 new gene duplication mutations to the previous version of the human genome.

"It really is understanding and cataloging these differences between genomes that allow us to understand how cells operate and their biology and how they function, as well as understanding genetic differences and how they contribute to understanding human disease," study co-author Karen Miga (opens in new tab), a geneticist at the University of California, Santa Cruz, said at a press conference held May 9.

The pangenome could help scientists get a better grasp of complex conditions in which genes play an influential role, such as autism, schizophrenia, immune disorders and coronary heart disease, researchers involved with the study said at the press conference.

For example, the Lipoprotein A gene is known to be one of the biggest risk factors for coronary heart disease in African Americans, but the specific genetic changes involved are complex and poorly understood, study co-author Evan Eichler (opens in new tab), a genomics researcher at the University of Washington in Seattle, told reporters. With the pangenome, researchers can now more thoroughly compare the variation in people with heart disease and without, and this could help clarify individuals' risk of heart disease based on what variants of the gene they carry.

Related: As little as 1.5% of our genome is 'uniquely human'

The current pangenome draft used data from participants in the 1000 Genomes Project, which was the first attempt to sequence genomes from a large number of people from around the world. The included participants had agreed for their genetic sequences to be anonymized and included in publicly available databases.

The new study also used advanced sequencing technology called "long-read sequencing," as opposed to the short-read sequencing that came before. Short-read sequencing is what happens when you send your DNA to a company like 23andMe, Eichler said. Researchers read out small segments of DNA and then stitch them together into a whole. This kind of sequencing can capture a decent amount of genetic variation, but there can be poor overlap between each DNA fragment. Long-read sequencing, on the other hand, captures big segments of DNA all at once.

While it's possible to sequence a genome with short-read sequencing for about $500, long-read sequencing is still expensive, costing about $10,000 a genome, Eichler said. The price is coming down, however, and the pangenome team hopes to sequence their next batches of genomes at half that cost or less.

The researchers are working to recruit new participants to continue to fill in diversity gaps in the pangenome, study co-author Eimear Kenny (opens in new tab), a professor of medicine and genetics at the Institute for Genomic Health at Icahn School of Medicine at Mount Sinai in New York City, told reporters. Because genetic information is sensitive and because different rules govern data-sharing and privacy in different countries, this is delicate work. Issues include privacy, informed consent, and the possibility of discrimination based on genetic information, Kenny said.

Already, researchers are uncovering new genetic processes with the draft pangenome. In two papers published in Nature alongside the work, researchers looked at highly repetitive segments of the genome. These segments have traditionally been difficult to study, biochemist Brian McStay (opens in new tab) of the National University of Ireland Galway, told Live Science, because sequencing them via short-read technology makes it hard to understand how they fit together. The long read technology allows for long chunks of these repetitive sequences to be read at once.

The studies found that in one type of repetitive sequence (opens in new tab), known as segmental duplications, there is a larger than expected amount of variation, potentially a mechanism for the long-term evolution of new functions for genes. In another type of repetitive sequence (opens in new tab) that is responsible for building the cellular machines that create new proteins, though, the genome stays remarkably stable. The pangenome allowed researchers to discover a potential mechanism for how these key segments of DNA stay consistent over time.

"This is just the start," McStay said. "There will be a whole lot of new biology that will come out of this."

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A Brief Guide to Genomics – National Human Genome Research Institute

Posted: May 17, 2023 at 12:13 am

Virtually every human ailment has some basis in our genes. Until recently, doctors were able to take the study of genes, or genetics, into consideration only in cases of birth defects and a limited set of other diseases. These were conditions, such as sickle cell anemia, which have very simple, predictable inheritance patterns because each is caused by a change in a single gene.

With the vast trove of data about human DNA generated by the Human Genome Project and other genomic research, scientists and clinicians have more powerful tools to study the role that multiple genetic factors acting together and with the environment play in much more complex diseases. These diseases, such as cancer, diabetes, and cardiovascular disease constitute the majority of health problems in the United States. Genome-based research is already enabling medical researchers to develop improved diagnostics, more effective therapeutic strategies, evidence-based approaches for demonstrating clinical efficacy, and better decision-making tools for patients and providers. Ultimately, it appears inevitable that treatments will be tailored to a patient's particular genomic makeup. Thus, the role of genetics in health care is starting to change profoundly and the first examples of the era of genomic medicine are upon us.

It is important to realize, however, that it often takes considerable time, effort, and funding to move discoveries from the scientific laboratory into the medical clinic. Most new drugs based on genome-based research are estimated to be at least 10 to 15 years away, though recent genome-driven efforts in lipid-lowering therapy have considerably shortened that interval. According to biotechnology experts, it usually takes more than a decade for a company to conduct the kinds of clinical studies needed to receive approval from the Food and Drug Administration.

Screening and diagnostic tests, however, are here. Rapid progress is also being made in the emerging field of pharmacogenomics, which involves using information about a patient's genetic make-up to better tailor drug therapy to their individual needs.

Clearly, genetics remains just one of several factors that contribute to people's risk of developing most common diseases. Diet, lifestyle, and environmental exposures also come into play for many conditions, including many types of cancer. Still, a deeper understanding of genetics will shed light on more than just hereditary risks by revealing the basic components of cells and, ultimately, explaining how all the various elements work together to affect the human body in both health and disease.

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Human genetics – Immunogenetics | Britannica

Posted: April 23, 2023 at 12:14 am

Immunity is the ability of an individual to recognize the self molecules that make up ones own body and to distinguish them from such nonself molecules as those found in infectious microorganisms and toxins. This process has a prominent genetic component. Knowledge of the genetic and molecular basis of the mammalian immune system has increased in parallel with the explosive advances made in somatic cell and molecular genetics.

There are two major components of the immune system, both originating from the same precursor stem cells. The bursa component provides B lymphocytes, a class of white blood cells that, when appropriately stimulated, differentiate into plasma cells. These latter cells produce circulating soluble proteins called antibodies or immunoglobulins. Antibodies are produced in response to substances called antigens, most of which are foreign proteins or polysaccharides. An antibody molecule can recognize a specific antigen, combine with it, and initiate its destruction. This so-called humoral immunity is accomplished through a complicated series of interactions with other molecules and cells; some of these interactions are mediated by another group of lymphocytes, the T lymphocytes, which are derived from the thymus gland. Once a B lymphocyte has been exposed to a specific antigen, it remembers the contact so that future exposure will cause an accelerated and magnified immune reaction. This is a manifestation of what has been called immunological memory.

The thymus component of the immune system centres on the thymus-derived T lymphocytes. In addition to regulating the B cells in producing humoral immunity, the T cells also directly attack cells that display foreign antigens. This process, called cellular immunity, is of great importance in protecting the body against a variety of viruses as well as cancer cells. Cellular immunity is also the chief cause of the rejection of organ transplants. The T lymphocytes provide a complex network consisting of a series of helper cells (which are antigen-specific), amplifier cells, suppressor cells, and cytotoxic (killer) cells, all of which are important in immune regulation.

One of the central problems in understanding the genetics of the immune system has been in explaining the genetic regulation of antibody production. Immunobiologists have demonstrated that the system can produce well over one million specific antibodies, each corresponding to a particular antigen. It would be difficult to envisage that each antibody is encoded by a separate gene; such an arrangement would require a disproportionate share of the entire human genome. Recombinant DNA analysis has illuminated the mechanisms by which a limited number of immunoglobulin genes can encode this vast number of antibodies.

Each antibody molecule consists of several different polypeptide chainsthe light chains (L) and the longer heavy chains (H). The latter determine to which of five different classes (IgM, IgG, IgA, IgD, or IgE) an immunoglobulin belongs. Both the L and H chains are unique among proteins in that they contain constant and variable parts. The constant parts have relatively identical amino acid sequences in any given antibody. The variable parts, on the other hand, have different amino acid sequences in each antibody molecule. It is the variable parts, then, that determine the specificity of the antibody.

Recombinant DNA studies of immunoglobulin genes in mice have revealed that the light-chain genes are encoded in four separate parts in germ-line DNA: a leader segment (L), a variable segment (V), a joining segment (J), and a constant segment (C). These segments are widely separated in the DNA of an embryonic cell, but in a mature B lymphocyte they are found in relative proximity (albeit separated by introns). The mouse has more than 200 light-chain variable region genes, only one of which will be incorporated into the proximal sequence that codes for the antibody production in a given B lymphocyte. Antibody diversity is greatly enhanced by this system, as the V and J segments rearrange and assort randomly in each B-lymphocyte precursor cell. The mechanisms by which this DNA rearrangement takes place are not clear, but transposons are undoubtedly involved. Similar combinatorial processes take place in the genes that code for the heavy chains; furthermore, both the light-chain and heavy-chain genes can undergo somatic mutations to create new antibody-coding sequences. The net effect of these combinatorial and mutational processes enables the coding of millions of specific antibody molecules from a limited number of genes. It should be stressed, however, that each B lymphocyte can produce only one antibody. It is the B lymphocyte population as a whole that produces the tremendous variety of antibodies in humans and other mammals.

Plasma cell tumours (myelomas) have made it possible to study individual antibodies, since these tumours, which are descendants of a single plasma cell, produce one antibody in abundance. Another method of obtaining large amounts of a specific antibody is by fusing a B lymphocyte with a rapidly growing cancer cell. The resultant hybrid cell, known as a hybridoma, multiplies rapidly in culture. Since the antibodies obtained from hybridomas are produced by clones derived from a single lymphocyte, they are called monoclonal antibodies.

As has been stated, cellular immunity is mediated by T lymphocytes that can recognize infected body cells, cancer cells, and the cells of a foreign transplant. The control of cellular immune reactions is provided by a linked group of genes, known as the major histocompatibility complex (MHC). These genes code for the major histocompatibility antigens, which are found on the surface of almost all nucleated somatic cells. The major histocompatibility antigens were first discovered on the leukocytes (white blood cells) and are therefore usually referred to as the HLA (human leukocyte group A) antigens.

The advent of the transplantation of human organs in the 1950s made the question of tissue compatibility between donor and recipient of vital importance, and it was in this context that the HLA antigens and the MHC were elucidated. Investigators found that the MHC resides on the short arm of chromosome 6, on four closely associated sites designated HLA-A, HLA-B, HLA-C, and HLA-D. Each locus is highly polymorphic; i.e., each is represented by a great many alleles within the human gene pool. These alleles, like those of the ABO blood group system, are expressed in codominant fashion. Because of the large number of alleles at each HLA locus, there is an extremely low probability of any two individuals (other than siblings) having identical HLA genotypes. (Since a person inherits one chromosome 6 from each parent, siblings have a 25 percent probability of having received the same paternal and maternal chromosomes 6 and thus of being HLA matched.)

Although HLA antigens are largely responsible for the rejection of organ transplants, it is obvious that the MHC did not evolve to prevent the transfer of organs from one person to another. Indeed, information obtained from the histocompatibility complex in the mouse (which is very similar in its genetic organization to that of the human) suggests that a primary function of the HLA antigens is to regulate the number of specific cytotoxic T killer cells, which have the ability to destroy virus-infected cells and cancer cells.

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A Troublesome Inheritance – Wikipedia

Posted: April 23, 2023 at 12:14 am

2014 book by Nicholas Wade

A Troublesome Inheritance: Genes, Race and Human History is a 2014 book by Nicholas Wade, a British writer, journalist, and former science and health editor for The New York Times.[1][2][3][4] In the book, Wade argues that human evolution has been "recent, copious and regional"[5][6][7] and that this has important implications for social sciences.[8] The book has been widely denounced by the scientific community for misrepresenting research into human population genetics.[9][10][11]

Wade writes about racial differences in economic success between Whites, Blacks, and East Asians, and offers the argument that racial differences come from genetic differences amplified by culture. In the first part of the book, Wade provides an account of human genetics research. In the second part of his book, Wade proposes that regional differences in evolution of social behavior explain many differences among different human societies around the world.[12]

The book has been widely denounced by scientists, including many of those upon whose work the book was based.[9][10][11][13] On 8 August 2014, The New York Times Book Review published an open letter signed by 139 faculty members in population genetics and evolutionary biology[9][10] which read:[13]

Wade juxtaposes an incomplete and inaccurate account of our research on human genetic differences with speculation that recent natural selection has led to worldwide differences in I.Q. test results, political institutions and economic development. We reject Wade's implication that our findings substantiate his guesswork. They do not.

We are in full agreement that there is no support from the field of population genetics for Wade's conjectures.[13]

After publication, the letter was signed by four more faculty members.[11] In reply, Wade wrote, "This letter is driven by politics, not science. I am confident that most of the signatories have not read my book and are responding to a slanted summary devised by the organizers."[9][14] Wade added that he had asked the letter's main authors, Graham Coop and Michael Eisen, for a list of errors so that he could correct future editions of the book.[10][14]

Evolutionary geneticist Mark Jobling, one of the signatories to the letter, wrote an opinion piece in the peer-reviewed journal Investigative Genetics explaining that the unprecedented letter was necessary due to both the fallacious nature of Wade's argument and its political ramifications, stating that "Its enthusiastic proponents already include some high profile white supremacists and a former Grand Wizard of the Ku Klux Klan."[15] Biologist Marcus Feldman, another of the signatories to the letter, further criticized Wade's book, arguing that "By invoking Richard Lynn on racial variation in IQ and wealth, Wade departs from his 'speculative arena,' leaving us to infer not only that he is a devout hereditarian, but also that he is comfortable with Lynn's racist worldview."[16]

The book was further criticized in a series of five reviews by Agustn Fuentes, Jonathan M. Marks, Jennifer Raff, Charles C. Roseman and Laura R. Stein, which were published together in the scientific journal Human Biology.[17] Marks, for instance, described the book as "entirely derivative, an argument made from selective citations, misrepresentations, and speculative pseudoscience."[18] The publishers made all the reviews accessible on open access in order to facilitate discussions on the subject.[19]

Anthropologist Greg Laden writes that anthropologists were mostly critical of the book, while psychologists and economists generally received it more warmly.[7] Laden concludes that "A Troublesome Inheritance is itself troubling, not for its politics but for its science. Its arguments are only mildly amended versions of arguments discarded decades ago by those who methodically and systematically study human behavioral variation across cultures."[7]

Evolutionary biologist H. Allen Orr wrote in The New York Review of Books that "Wade's survey of human population genomics is lively and generally serviceable. It is not, however, without error. He exaggerates, for example, the percentage of the human genome that shows evidence of recent natural selection."[12] Orr comments that, in its second part, "the book resembles a heavily biological version of Francis Fukuyama's claims about the effect of social institutions on the fates of states in his The Origins of Political Order (2011)."[12] Orr criticizes Wade for failing to provide sufficient evidence for his claims, though according to Orr, Wade concedes that evidence for his thesis is "nearly nonexistent."[12] Orr further comments:

Wade also thinks that "evolutionary differences between societies on the various continents may underlie major and otherwise imperfectly explained turning points in history such as the rise of the West and the decline of the Islamic world and China." Here, and especially in his treatment of why the industrial revolution flourished in England, his book leans heavily on Gregory Clark's A Farewell to Alms (2007).[12]

Political scientist Charles Murray wrote a positive review in The Wall Street Journal,[20] calling the book "historic"[4] and stating that opposition to the book among academics would be motivated by "political correctness".[21] Economist Walter E. Block criticized parts of the book, but concluded Wade's "moral and intellectual courage cannot be denied".[22] Statistician Andrew Gelman writes, "As a statistician and political scientist, I see naivete in Wade's quickness to assume a genetic association for any change in social behavior."[23]

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Human – Simple English Wikipedia, the free encyclopedia

Posted: January 29, 2023 at 12:31 am

A human is a member of the species Homo sapiens, which means 'wise man' in Latin.[3] Carolus Linnaeus put humans in the mammalian order of primates.[1] Humans are a species of hominid, and chimpanzees, bonobos, gorillas and orangutans are their closest living relatives.

Humans are mammals. They are also social animals. They usually live in groups. They help and protect each other. They care for their children. Humans are bipedal, which means they walk on two legs.

Humans have a complex brain, which is much larger than that of the other living apes. They use language, make ideas, and feel emotions. This brain, and the fact that arms are not needed for walking, lets humans use tools. Humans use tools far more than any other species.

Humans first came from Africa. There are humans living on every continent.[4][5] As of 2022, there were over 7900 million people living on Earth.[6] Overpopulation is a problem.

Humans have a long period of development after birth. Their life depends less on instinct than other animals, and more on learning. Humans are also born with their brains not so well developed as those of other mammals. This makes for an unusually long childhood, and so makes family life important. If their brains were better developed at birth, their head would be larger, and this would make birth more difficult. In birth, the baby's head has to get through the 'birth canal', the passageway through the mother's pelvis.

Many animals use signs and sounds to communicate with each other. But humans have language. It lets them express ideas by using words. Humans are capable of making abstract ideas and communicating them to others. Human language can express things which are not present, or talk about events that are not happening at that time.[7] The things might be elsewhere, and the events may also have occurred at another place or time.[8]

No known animals have a system of communication that is as elaborate as human language. By using words to communicate with each other, humans make complex communities with laws, traditions and customs. Humans like to understand the world around them. They try to explain things through myth, science and philosophy. Wanting to understand things has helped humans make important discoveries.

Humans are the only species living today known to build fires, to cook their food and wear clothes. Humans use more technology than any other animal on Earth ever has. Humans like things that are beautiful and like to make art, literature and music. Humans use education and teaching to pass on skills, ideas and customs to the next generations.

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Humans are part of the animal kingdom. They are mammals, which means that they give birth to their young, and females feed their babies with breast milk. Humans belong to the order of primates. Apes like gorillas, orangutans, chimps, and gibbons are also primates.

The closest living relatives of humans are the two chimpanzee species: the common chimpanzee and the bonobo. Scientists have examined the genes of humans and chimpanzees, and compared their DNA. The studies showed that 95% to 99% of the DNA of humans and chimpanzees is the same.[9][10][11][12][13]

Biologists explain the similarity between humans and other hominoids by their descent from a common ancestor. In 2001, a hominid skull was discovered in Chad. The skull is about 7 million years old, and has been classified as Sahelanthropus tchadensis. This skull may show that the date at which humans started to evolve (develop differently) from other primates is 2 million years earlier than scientists had previously thought.[14]

Humans are part of a subfamily called the Homininae (or hominins), inside the hominids or great apes.

Long ago, there used to be other types of hominins on Earth. They were like modern humans, but not the same. Homo sapiens are the only type of hominins who are alive today.[15] The earliest known fossils of genus Homo have been called Homo habilis (handy man). The first fossils of Homo habilis were found in Tanzania. Homo hablilis is thought to have lived about 2.2 to 1.7 million years ago.[16] Another human species thought to be an ancestor of the modern human is Homo erectus.[17] There are other extinct species of Homo known today. Many of them were likely our 'cousins', as they developed differently than our ancestors.[18] Different species of plants and animals moved from Africa to the Middle East, and then elsewhere. Early humans may have moved from Africa to other parts of the world in the same way.

The first truly modern humans seem to have appeared between 300,000,[19] and 200,000 years ago in East Africa.[20][21][22] In paleontology, 200,000 years is a "short" time. So, scientists speak of a "recent single origin" of humans. Some of these early humans later moved out from Africa. By about 90,000 years ago they had moved into Eurasia. This was the area where Neanderthals, Homo neanderthalensis, had been living for a long time (at least 350,000 years).

By about 42 to 44,000 years ago Homo sapiens had reached western Europe, including Britain.[23] In Europe and western Asia, Homo sapiens replaced the neanderthals by about 35,000 years ago. The details of this event are not known.

At roughly the same time Homo sapiens arrived in Australia. Their arrival in the Americas was much later, about 15,000 years ago.[24] All these earlier groups of modern man were hunter-gatherers.

Early human history is commonly divided into three ages. The time periods are labeled with the material used for tools.

The "Stone Age" is commonly subdivided into the Paleolithic, Mesolithic, and Neolithic periods.

Up to about 10 thousand years ago most humans were hunter-gatherers. They did not live in one place, but moved around as the seasons changed. The start of planting crops for food, called farming made the Neolithic revolution. Some people chose to live in settlements. This also led to the invention of metal tools and the training of animals. About 6000 years ago the first proper civilizations began in places like Egypt, India, and Syria. The people formed governments and armies for protection. They competed for area to live and resources and sometimes they fought with each other. About 4000 years ago some states took over or conquered other states and made empires. Examples include ancient Greece and the Roman Empire.

Some modern day religions also began at this time such as Judaism and Hinduism. From the Middle Ages and beyond humanity saw an explosion of new technology and inventions. The printing press, the car, the train, and electricity are all examples of this kind of invention. As a result of the developments in technology, modern humans live in a world where everyone is connected, for example by telephone or by internet. People now control and change the environment around them in many different ways.

In early times, humans usually settled near to water and other natural resources. In modern times if people need things they can transport them from somewhere else. So basing a settlement close to resources is no longer as important as it once was. Since 1800, the number of humans, or population, has increased by six billion.[25] Most humans (61%) live in Asia. The rest live in the Americas (14%), Africa (14%), Europe (11%), and Oceania (0.5%).

Most people live in towns and cities. This number is expected to get higher. In 2005 the United Nations said that by the end of that year, over half the world would be living in cities. This is an important change in human settlement patterns: a century earlier in 1900 only 14% of people lived in cities, in 2000 47% of the world's population lived in cities. In developed countries, like the United States, 80% of the population live in cities.[26]

Humans have a large effect on the world. Humans are at the top of the food chain and are generally not eaten by any animals. Humans have been described as super predators because of this.[27] Because of industry and other reasons humans are said to be a big cause of global climate change.[28]

Human body measurements differ. The worldwide average height for an adult human male is about 172cm (5ft 7+12in), and the worldwide average height for adult human females is about 158cm (5ft 2in). The average weight of an adult human is 5464kg (119141lb) for females and 7083kg (154183lb) for males.[29][30] Body weight and body type is influenced by genetics and environment. It varies greatly among individuals.

Human hair grows on the underarms, the genitals, legs, arms, and on the top of the head in adults of both genders. Hair will usually grow on the face of most adult males, and on the chest and back of many adult males. In human children of both genders, long hair grows only on the top of the head. Although it might look like humans have fewer hairs than most primates, they actually do not. The average human has more hair follicles, where hair grows from, than most chimpanzees have.[31] Human hair can be black, brown, red or blond.[32] When humans get older hair can turn grey or white.

Human skin colors vary greatly. They can be a very pale pink all the way to dark brown. There is a reason why people in tropical areas have dark skins. The dark pigment (melanin) in the skin protects them against ultraviolet rays in sunlight. The damage caused by UV rays can and does cause skin cancer in some people. Therefore, in more sunny areas, natural selection favors darker skin color.[33][34] Sun tanning has nothing to do with this issue, because it is just a temporary process which is not inherited. In colder climates the advantage of light-coloured skin is two-fold. It radiates less heat, and it absorbs more sunlight. In weaker sunlight a darker body produces less vitamin D than a lighter body. The selection for lighter skin is driven by these two reasons. Therefore, in less sunny areas, natural selection favours lighter skin colour.[35][36][37]

Humans are not as strong as other primates of the same size. An average female orangutan is at least three times as strong as an average human.[38]

The average human male needs 7 to 8 hours sleep a day. People who sleep less than this are generally not as healthy. A child needs more sleep, 9 to 10 hours on average.

The human life cycle is similar in some ways to most other mammals. However, there are some differences. The young grow inside the female mother for nine months. After this time the baby is pushed out of the woman's vagina, with its brain only half developed.

Unlike most other mammals, human childbirth is somewhat dangerous. Babies' heads are large, and the mothers pelvis bones are not very wide. Since people walk on two legs, their hips are fairly narrow. This means that birth can be difficult. Rarely, mother or baby may die in childbirth.[39] The number of mothers dying in childbirth is less in the 21st century. This is because of better medication and treatment. In many poor countries the number of mothers dying is higher. Sometimes it is up to 10 times as many as richer countries.[40]

In the human female, her fertile period in the oestrous cycle is hidden, and mating can take place at any time. That is quite unusual. In mammals generally the fertile period is very noticeable. Mating only takes place when the female signals her fertility. Think about cats, for example. The human cycle is unusual, and it is thought that there is a reason. Humans band together in tribes which have many people. It helps the tribe if the father of a child is not known for certainty. Men live together and work together in much larger groups than do chimpanzees (our nearest living relatives). They have a collective interest in the tribe. It is thought that the human mating system helps this.[41][42]

The average human baby weighs 34 kg at birth and is 5060 cm tall. Babies are often smaller in poorer countries,[43] and may die early because of this.[44]

Humans have four stages in their lives: childhood, adolescence, adulthood and old age.

Life expectancy is how long you are expected to live. This depends on many things including where you live. The highest life expectancy is for people from Monaco, 89.52 years. The lowest is for people from Chad where life expectancy is only 49.81 years.[45]

Psychology is the study of how the human mind works. The human brain is the main controller of what a person does. Everything from moving and breathing to thinking is done by the brain. The human neocortex is huge compared with other mammals, and gives us our thinking ability, and the ability to speak and understand language.

Neurology is the study of how the brain works, psychology is the study of how and why people think and feel. Many aspects of life are also influenced by the hormone system, including growth and sexual development. The hormonal system (especially the pituitary gland) is partly controlled by the brain.

Human behaviour is hard to understand, so sometimes psychologists study animals because they may be simpler and easier to know. Psychology overlaps with many other sciences including medicine, biology, computer science and linguistics.

Language at its most basic is talking, reading and writing. The study of language is called linguistics. Humans have the most complicated languages on Earth. Although almost all animals communicate, human language is unique. Its use of syntax, and its huge learnt vocabulary are its main features.[8][46] There are over 7,300 languages spoken around the world. The world's most spoken first language is Mandarin Chinese, and the most spoken language is English.[47] This includes speakers of English as a second language.

Art has existed almost as long as humans. People have been doing some types of art for thousands of years as the picture on the right shows. Art represents how someone feels in the form of a painting, a sculpture or a photograph.

Music has also been around for thousands of years. Music can be made with only your voice but most of the time people use instruments. Music can be made using simple instruments only such as simple drums all the way up to electric guitars, keyboards and violins. Music can be loud, fast, quiet, slow or many different styles. Music represents how the people who are playing the music feel.

Literature is anything made or written using language. This includes books, poetry, legends, myths and fairy tales. Literature is important as without it many of the things we use today, such as Wikipedia, would not exist.

Humans often categorize themselves by race or ethnicity. Modern biologists know that human gene sequences are very similar compared to many other animals.[48][49][50] This is because of the "recent single origin" of modern humans.[22] That is one reason why there is only one human race.[51][52]:360

Ethnic groups are often linked by linguistic, cultural, ancestral, and national or regional ties. Race and ethnicity can lead to different social treatment called racism.

Religion is a belief of faith in a higher being, spirit, or any system of ideas that a group of people believe in. To have faith in a belief is to have the belief without proof that it is true. Faith can bring people together because they all believe in the same thing. Some of the things religions talk about are what happens after death, why humans exist, how humans came to exist (creation), and what is good to do and not to do (morality). Some people are very religious. Many people believe in one all-powerful god; some people believe in more than one god; some people are atheists, who do not believe in a god; and some people are agnostics, who are not sure if there is a god.

Technology are the things and methods which humans use to make tasks easier. Science is understanding how the universe and the things in it work. Technology used to be quite simple. It was passed on by people telling others, until writing was invented. This allowed technology to develop much quicker. Now people understand more and more about the world and the universe. The use of the telescope by Galileo, Einstein's theory of relativity, lasers, and computing are all scientific discoveries. Technology is of great importance to science, to medicine, and to everyday life.

A war is a lethal fight between large groups of people, usually countries or states. A war involves the use of lethal weapons as both sides try to kill the other. It is estimated that during the 20th century, between 167 and 188 million humans died because of war.[53] The people who fight for a state in wars are called soldiers. The people who fight in wars, but not for a state, are usually called "fighters".

Modern wars are very different from wars a thousand or even a hundred years ago. Modern war involves sabotage, terrorism, propaganda, and guerrilla warfare. In modern-day wars, civilians (people who are not soldiers) are often targets. An example of this is the nuclear bomb dropped on Hiroshima and Nagasaki at the end of World War II. The bombs killed as many as 140,000 people in Hiroshima and 80,000 in Nagasaki by the end of 1945,[54] about half on the days of the bombings. Since then, thousands more have died from wounds or illness because of exposure to radiation released by the bombs.[55] In both cities, the overwhelming majority of the dead were civilians. In Germany, Austria, and Great Britain, conventional bombs were used. About 60,595 British,[56] and 550,000 German,[57] civilians were killed by planes bombing cities.

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Human Genetics and Genomics Training Program – Hopkins Medicine

Posted: January 4, 2023 at 1:07 am

The Johns Hopkins Training program in Human Genetics and Genomics (HGG program) provides students with a robust foundation in all aspects of human genetics and genomics. In particular, the consequences of variation in our genomes on cellular biology, biochemistry, metabolism, development, physiology and, ultimately, human phenotypes. Building on this foundation, our trainees explore the array of mechanisms by which genetic variation interacts with environmental variables to contribute to disease mechanisms and risk, explored through the lens of normal and disease states in human biology and organ systems. The program provides an alternative to the combined M.D./Ph.D. program for those who want to carry out genetic studies in man but do not want the M.D. degree.

Our students become increasingly skilled and independent in adding to their knowledge and in identifying key questions and incisive approaches that can advance their fields. The ability to design incisive experiments that appropriately employ quantitative methods to analyze and interpret the data with rigor and integrity is central to their training.

The HGG program also strives to provide students with a diverse and inclusive environment and supports acquisition of fundamental skills for their chosen career path, including written and oral communication skills. Throughout their training, students are provided with opportunities to acquire the professional skills and experiences needed to guide selection of, and facilitate transition into, any number of relevant careers, including research in academia and industry, teaching, science-writing, policy, law, and consulting.

Johns Hopkins University was ranked as the #6 top graduate training school for genetics/genomics/bioinformatics by the U.S. News and World Report in 2022.

The HGG program is distinct from other programs in the JHU School of Medicine in its emphasis on human genetic variation; in particular, the origins, population distribution, and consequences for gene regulatory networks and, hence, phenotypic effects of human genetic variation. In essence, how genetic variation interacts with environmental variables to contribute to human health and disease. HGG remains one of the most prominent PhD training programs in genetics nationwide, producing incisive and creative thought leaders, skilled in the use of emerging genetic tools to dissect problems in human biology/clinical medicine.

A curriculum equipped for the challenges in 21st century genetics as applied to human biology and medicine: The rapidly expanding appreciation of genetic variation in medicine and health has arisen in tandem with dramatic technological advances. Holding this in tension with foundational concepts in genetics has necessitated a significant evolution of our training paradigm. HGG provides a unique training experience. Our revised curriculum integrates training in genetics, molecular and cellular biology with training in human pathobiology, disease mechanisms, computational and genomic tools, to equip HGG trainees for the emerging role of genetics in health.

Built for data: Contemporary genetic research increasingly necessitates computational competence and utilization of large data sets. The diverse and highly integrated HGG preceptor community includes a uniquely trained cohort of computational geneticists with deep training in phenotype definition, clinical disease, machine learning and genetic variation preparing our students for current and future data-driven discoveries. Of recently matriculated students, 31% are engaged in computationally intensive research.

Unique exposure to the interface between patient care and research: We take advantage of our position in a prominent school of medicine to provide HGG students with several unique opportunities. Among these, many students attend the weekly DGM Clinical Case Conference, allowing students to place genetic research in a clinically relevant context. Our students have the opportunity to work alongside the clinical and genetic counseling teams in preparing reports for the Online Mendelian Inheritance in Man (OMIM). This provides writing, clinical and professional development opportunities for our trainees that are not available elsewhere. We offer an elective, Understanding genetic disease, where students each observe a patient/family in a clinic under medical geneticist/counselor supervision. In class, they summarize the clinical issues and further discuss the epidemiology, pathogenesis, molecular genetic bases, treatment options, potential clinical trials, and research needs of the condition.

A training environment that promotes student initiatives and inclusivity: The HGG program promotes and has adopted student-initiatives to enhance diversity and inclusivity. These include a HGG-initiated, JHUSOM-wide committee and seminar series to address issues impacting the role and visibility of individuals with physical and mental disabilities in science and medicine (Equal Access in Science and Medicine); a seminar and discussion forum within HGG that addresses issues of race and gender-based inequities in genetics (Equity in Genetics); and a forward-looking effort to foster relationships with historically black colleges and universities (HBCU) to enhance research experience and expand opportunity for careers in science amongst undergraduates populations that are underrepresented in science (BUILD2ASCEND). We are currently planning with Dr Hohmann (PI of the BUILD grant at Morgan State University; MSU), to establish a long-term commitment to the program at MSU (and other HBCU). We aim to begin by developing a mini-symposium by HGG students presenting their thesis research to engage interested MSU students. This will provide HGG students with teaching and mentorship experience and provide MSU students with research and career development experience that have immediate and long-term consequences.

The Johns HopkinsTraining Program in Human Genetics and Genomics (HGG) has grown steadily since its inception in 1980 in parallel with the spectacular growth of genetics and genomics and their application to medicine over the last three decades. Similarly, the Johns Hopkins School of Medicine (SOM) continues to make commitments to human genetics as evidenced by the establishment of the McKusick-Nathans Institute of Genetic Medicine (IGM) in 1999, and the McKusick-Nathans Institute of Genetic Medicine | Department of Genetic Medicine (DGM) in 2019; as well as the provision of state of the art research space in 2004, and the 2009 introduction of a new medical school curriculum known as The Genes to Society curriculum, which has genetics and genetic-thinking as an underlying principle. In 2013, the DGM continued to grow with the field by partnering with the Johns Hopkins Bloomberg School of Public Health (JHSPH) and the National Human Genome Research Institute (NHGRI) to create the Maryland Genetics, Epidemiology, and Medicine Training Program (MD-GEM), funded by the Burroughs Wellcome Fund/MD-GEM takes a multidisciplinary approach by combining the expertise of all three institutions, to foster the development of a new generation of scientists.

Director: Andrew McCallion, Ph.D.Email: andy@jhmi.edu

Co-Director:Kimberly Doheny, Ph.D.Email: kdoheny@jhmi.edu

Administrator:Sandy MuscelliEmail: muscelli@jhmi.edu

The directors work closely with the Program Administrator, Ms. Sandy Muscelli, to deal with the day-to-day responsibilities of the program. Dr. McCallion served as Assistant Director for several years and provides valuable guidance to students throughout their training. Dr. Doheny is a 1993 graduate of the Human Genetics Program, providing guidance in the areas of large-scale genomics, technology development, clinical diagnostics and career development. Ms. Muscelli continues to serve as the Administrator for HGG, a position she has held since 1989. She organizes all aspects of the recruitment and admission processes, manages the budget, and handles the daily administrative duties. She should be the first person you contact if you have problems.

Additional input is provided by members of the Executive Committee: David Valle (chair), Professor of Genetic Medicine and former training program director from 1988-2021, Dan Arking, Professor of Genetic Medicine, Mary Armanios, Professor of Oncology, Hilary Vernon, Associate Professor of Genetic Medicine and Ambrose Wonkam, Professor and Director, Department of Genetic Medicine. All members of the Executive Committee are extensively involved in the selection and recruitment of our students and in counseling students with questions and/or problems.

Student Representatives are elected from each class to speak on behalf of students throughout their graduate careers. Responsibilities include organizing events throughout the academic year including the Barton Childs Lecture and events, student activities related to recruiting, the practice talks for students prior to their comprehensive exams, and orientation for the incoming first years. Additionally, the senior student representative attends faculty meeting and convey pertinent information from these meetings to all HGG students. When necessary, they act as a conduit between the students and program administration.

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Human Genetics and Molecular Biology, PhD – Johns Hopkins University

Posted: December 18, 2022 at 12:33 am

Ph.D. Program

The Johns Hopkins Human Genetics Training Program provides a training in all aspects of human genetics and genomics relevant to human biology, health and disease.

The overall objective of the Human Genetics program is to provide our students with a strong foundation in basic science by exposure to a rigorous graduate education in genetics, genomics, molecular biology, cell biology, biochemistry and biostatistics as well as a core of medically-related courses selected to provide knowledge of human biology in health and disease. Advances in human genetics and genomics continue at an astounding rate and increasingly they are being integrated into medical practice. The Johns Hopkins Predoctoral Training Program in Human Genetics (HG) aims to educate highly motivated and capable students with the knowledge and experimental tools that will enable them to answer important questions at the interface between genetics and medicine. Ultimately, our trainees will be the leaders in delivering the promise of genetics to human health.

The Human Genetics Program has also partnered with the Johns Hopkins Bloomberg School of Public Health (JHSPH) and the National Human Genome Research Institute (NHGRI) in establishing the Maryland Genetics, Epidemiology, and Medicine Training Program (MD-GEM). Funded by the Burroughs Wellcome Fund, MD-GEM takes a multidisciplinary approach by combining the expertise of all three institutions, to foster the development of a new generation of scientists. Interested Human Genetics students can participate in this additional training.

This program is also offered as training for medical students in the combined M.D./Ph.D. program. Students apply to the combined program at the time of application to the M.D. program. (See section entitled Medical Scientist Training Program).

Research laboratories are well equipped to carry out sophisticated research in all areas of genetics. The proximity to renown clinical facilities of the Johns Hopkins Hospital, including the Department of Genetic Medicine, and Oncology Center provides faculty and students with access to a wealth of material for study. Computer and library facilities are excellent. Because the program in human genetics is a university-wide activity, supporting facilities are extensive.

The program is supported by a limited number of teaching assistantships and predoctoral training funds from the National Institutes of Health. These fellowships, which are restricted to United States citizens and permanent United States residents, cover tuition and provide monthly stipends and are awarded to essentially all students in the program. Students are encouraged, however, to apply for fellowships from outside sources (e.g., the National Science Foundation, Howard Hughes Medical Institute) before entering the program.

Applicants for admission should show a strong academic foundation with coursework in biology, chemistry and quantitative analysis. Applicants are encouraged to have exposure to lab research or to data science. A bachelor's degree from a qualified college or university will be required for matriculation. We no longer require GREs to be taken.

The Human Genetics site has up-to-date information on How to Apply. For questions not addressed on these pages, please email Sandy Muscelli, the program administrator, at muscelli@jhmi.edu.

The program includes the following required core courses: Molecular Biology and Genomics, Cell Structure, Computational Bootcamp, Pathways and Regulation, Human Genetics, Evolving Concept of a Gene, Basic Mechanisms of Disease, Genomic Technologies, Rigor and Reproducibility in Research, Molecular Mechanisms of Disease and Systems, Genes and Mechanisms of Disease, some of which are listed in the entries of the departments of Cell Biology, Molecular Biology and Genetics, Biological Chemistry and Cell Biology. Numerous elective courses are available and are listed under sponsoring departments.

Our students must take a minimum of four electives, one of which must provide computational/statistical training.

Our students also take a two-week course in July at the Jackson Labs in Bar Harbor, Maine entitled "Human and Mammalian Genetics and Genomics: The McKusick Short Course" which covers the waterfront from basic principles to the latest developments in mammalian genetics. The faculty numbers about 50 and consists roughly in thirds of JAX faculty, Hopkins faculty and guest faculty comprising outstanding mammalian geneticists from other US universities and around the world.

The courses offered by the faculty of the program are listed below. All courses are open to graduate students from any university program as well as selected undergraduates with permission of the course director.

Students must complete three research rotations before deciding on their thesis lab. They must also participate in the Responsible Conduct of Research sessions offered by the Biomedical Program; starting at year 3, students must attend at least two Research Integrity Colloquium lectures per year.

Our students participate in weekly journal clubs, department seminars,monthly Science & Pizza presentations as well as workshops given twice a year on diversity, identity and culture.

At the end of the second year, students take their Doctoral Board Oral Examination. Annual thesis committee meetings must be held following successful completion of this exam.

Average time for completion is 5.5 years.

Graduates from the Human Genetics program pursue careers in academia, medicine, industry, teaching, government,law, as well the private sector. Our trainees are encouraged to explore the full spectrum of professional venues in which their training my provide a strong foundation. Driven by curiosity and a desire for excellence, our trainees stand out as leaders in the chosen arenas of professional life. They are supported in the development of their career plans by a program faculty and administration who are dedicated to their success, and by a myriad of support networks across the Johns Hopkins University, many of which are provided by the Professional Development Career Office of the School of Medicine.

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Genetics vs. Genomics Fact Sheet – Genome.gov

Posted: December 18, 2022 at 12:33 am

Proteomics

The suffix "-ome" comes from the Greek for all, every, or complete. It was originally used in "genome," which refers to all the genes in a person or other organism. Due to the success of large-scale biology projects such as the sequencing of the human genome, the suffix "-ome" is now being used in other research contexts. Proteomics is an example. The DNA sequence of genes carries the instructions, or code, for building proteins. This DNA is transcribed into a related molecule, RNA, which is then translated into proteins. Proteomics, therefore, is a similar large-scale analysis of all the proteins in an organism, tissue type, or cell (called the proteome). Proteomics can be used to reveal specific, abnormal proteins that lead to diseases, such as certain forms of cancer.

Pharmacogenetics and Pharmacogenomics

The terms "pharmacogenetics" and "pharmacogenomics" are often used interchangeably in describing the intersection of pharmacology (the study of drugs, or pharmaceuticals) and genetic variability in determining an individual's response to particular drugs. The terms may be distinguished in the following way.

Pharmacogenetics is the field of study dealing with the variability of responses to medications due to variation in single genes. Pharmacogenetics takes into account a person's genetic information regarding specific drug receptors and how drugs are transported and metabolized by the body. The goal of pharmacogenetics is to create an individualized drug therapy that allows for the best choice and dose of drugs. One example is the breast cancer drug trastuzumab (Herceptin). This therapy works only for women whose tumors have a particular genetic profile that leads to overproduction of a protein called HER2. (See: Genetics, Disease Prevention and Treatment)

Pharmacogenomics is similar to pharmacogenetics, except that it typically involves the search for variations in multiple genes that are associated with variability in drug response. Since pharmacogenomics is one of the large-scale "omic" technologies, it can examine the entirety of the genome, rather than just single genes. Pharmacogenomic studies may also examine genetic variation among large groups of people (populations), for example, in order to see how different drugs might affect different racial or ethnic groups.

Pharmacogenetic and pharmacogenomic studies are leading to drugs that can be tailor-made for individuals, and adapted to each person's particular genetic makeup. Although a person's environment, diet, age, lifestyle, and state of health can also influence that person's response to medicines, understanding an individual's genetic makeup is key to creating personalized drugs that work better and have fewer side effects than the one-size-fits-all drugs that are common today. (See: Genetics, Disease Prevention and Treatment). For example, the U.S. Food and Drug Administration (FDA) recommends genetic testing before giving the chemotherapy drug mercaptopurine (Purinethol) to patients with acute lymphoblastic leukemia. Some people have a genetic variant that interferes with their ability to process this drug. This processing problem can cause severe side effects, unless the standard dose is adjusted according to the patient's genetic makeup. (See: Frequently Asked Questions about Pharmacogenomics).

Stem Cell Therapy

Stem cells have two important characteristics. First, stem cells are unspecialized cells that can develop into various specialized body cells. Second, stem cells are able to stay in their unspecialized state and make copies of themselves. Embryonic stem cells come from the embryo at a very early stage in development (the blastocyst staqe). The stem cells in the blastocyst go on to develop all of the cells in the complete organism. Adult stem cells come from more fully developed tissues, like umbilical cord blood in newborns, circulating blood, bone marrow or skin.

Medical researchers are investigating the use of stem cells to repair or replace damaged body tissues, similar to whole organ transplants. Embryonic stem cells from the blastocyst have the ability to develop into every type of tissue (skin, liver, kidney, blood, etc.) found in an adult human. Adult stem cells are more limited in their potential (for example, stem cells from liver may only develop into more liver cells). In organ transplants, when tissues from a donor are placed into the body of a patient, there is the possibility that the patient's immune system may react and reject the donated tissue as "foreign." However, by using stem cells, there may be less risk of this immune rejection, and the therapy may be more successful.

Stem cells have been used in experiments to form cells of the bone marrow, heart, blood vessels, and muscle. Since the 1990's, umbilical cord blood stem cells have been used to treat heart and other physical problems in children who have rare metabolic conditions, or to treat children with certain anemias and leukemias. For example, one of the treatment options for childhood acute lymphoblastic leukemia [cancer.gov] is stem cell transplantation therapy.

There has been much debate nationally about the use of embryonic stem cells, especially about the creation of human embryos for use in experiments. In 1995, Congress enacted a ban on federal financing for research using human embryos. However, these restrictions have not stopped researchers in the United States and elsewhere from using private funding to create new embryonic cell lines and undertaking research with them. The embryos for such research are typically obtained from embryos that develop from eggs that have been fertilized in vitro - as in an in vitro fertilization clinic - and then donated for research purposes with informed consent of the donors. In 2009, some of the barriers to federal financing of responsible and scientifically worthy human stem cell research were lifted.

Cloning

Cloning can refer to genes, cells, or whole organisms. In the case of a cell, a clone refers to any genetically identical cell in a population that comes from a single, common ancestor. For example, when a single bacterial cell copies its DNA and divides thousands of times, all of the cells that are formed will contain the same DNA and will be clones of the common ancestor bacterial cell. Gene cloning involves manipulations to make multiple identical copies of a single gene from the same ancestor gene. Cloning an organism means making a genetically identical copy of all of the cells, tissues, and organs that make up the organism. There are two major types of cloning that may relate to humans or other animals: therapeutic cloning and reproductive cloning.

Therapeutic cloning involves growing cloned cells or tissues from an individual, such as new liver tissue for a patient with a liver disease. Such cloning attempts typically involve the use of stem cells. The nucleus will be taken from a patient's body cell, such as a liver cell, and inserted into an egg that has had its nucleus removed. This will ultimately produce a blastocyst whose stem cells could then be used to create new tissue that is genetically identical to that of the patient.

Reproductive cloning is a related process used to generate an entire animal that has the same nuclear DNA as another currently or previously existing animal. The first cloned animals were frogs. Dolly, the famous sheep, is another example of cloning. The success rates of reproductive animal cloning, however, have been very low. In 2005, South Korean researchers claimed to have produced human embryonic stem cell lines by cloning genetic material from patients. However, this data was later reported to have been falsified.

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Race (human categorization) – Wikipedia

Posted: December 2, 2022 at 12:28 am

Grouping of humans based on shared physical or social qualities into categories

A race is a categorization of humans based on shared physical or social qualities into groups generally viewed as distinct within a given society.[1] The term came into common usage during the 1500s, when it was used to refer to groups of various kinds, including those characterized by close kinship relations.[2] By the 17th century, the term began to refer to physical (phenotypical) traits, and then later to national affiliations. Modern science regards race as a social construct, an identity which is assigned based on rules made by society.[3][4] While partly based on physical similarities within groups, race does not have an inherent physical or biological meaning.[1][5][6] The concept of race is foundational to racism, the belief that humans can be divided based on the superiority of one race over another.

Social conceptions and groupings of races have varied over time, often involving folk taxonomies that define essential types of individuals based on perceived traits.[7] Today, scientists consider such biological essentialism obsolete, and generally discourage racial explanations for collective differentiation in both physical and behavioral traits.[9][10][11][12][13]

Even though there is a broad scientific agreement that essentialist and typological conceptions of race are untenable,[14][15][16][17][18][19] scientists around the world continue to conceptualize race in widely differing ways.[20] While some researchers continue to use the concept of race to make distinctions among fuzzy sets of traits or observable differences in behavior, others in the scientific community suggest that the idea of race is inherently naive[9] or simplistic.[21] Still others argue that, among humans, race has no taxonomic significance because all living humans belong to the same subspecies, Homo sapiens sapiens.[22][23]

Since the second half of the 20th century, race has been associated with discredited theories of scientific racism, and has become increasingly seen as a largely pseudoscientific system of classification. Although still used in general contexts, race has often been replaced by less ambiguous and/or loaded terms: populations, people(s), ethnic groups, or communities, depending on context.[24][25]

Modern scholarship views racial categories as socially constructed, that is, race is not intrinsic to human beings but rather an identity created, often by socially dominant groups, to establish meaning in a social context. Different cultures define different racial groups, often focused on the largest groups of social relevance, and these definitions can change over time.

The establishment of racial boundaries often involves the subjugation of groups defined as racially inferior, as in the one-drop rule used in the 19th-century United States to exclude those with any amount of African ancestry from the dominant racial grouping, defined as "white".[1] Such racial identities reflect the cultural attitudes of imperial powers dominant during the age of European colonial expansion.[5] This view rejects the notion that race is biologically defined.[28][30]

According to geneticist David Reich, "while race may be a social construct, differences in genetic ancestry that happen to correlate to many of today's racial constructs are real."[32] In response to Reich, a group of 67 scientists from a broad range of disciplines wrote that his concept of race was "flawed" as "the meaning and significance of the groups is produced through social interventions".[33]

Although commonalities in physical traits such as facial features, skin color, and hair texture comprise part of the race concept, this linkage is a social distinction rather than an inherently biological one.[1] Other dimensions of racial groupings include shared history, traditions, and language. For instance, African-American English is a language spoken by many African Americans, especially in areas of the United States where racial segregation exists. Furthermore, people often self-identify as members of a race for political reasons.[1]

When people define and talk about a particular conception of race, they create a social reality through which social categorization is achieved. In this sense, races are said to be social constructs.[35] These constructs develop within various legal, economic, and sociopolitical contexts, and may be the effect, rather than the cause, of major social situations.[clarify][36] While race is understood to be a social construct by many, most scholars agree that race has real material effects in the lives of people through institutionalized practices of preference and discrimination.[citation needed]

Socioeconomic factors, in combination with early but enduring views of race, have led to considerable suffering within disadvantaged racial groups.[37] Racial discrimination often coincides with racist mindsets, whereby the individuals and ideologies of one group come to perceive the members of an outgroup as both racially defined and morally inferior.[38] As a result, racial groups possessing relatively little power often find themselves excluded or oppressed, while hegemonic individuals and institutions are charged with holding racist attitudes.[39] Racism has led to many instances of tragedy, including slavery and genocide.[40]

In some countries, law enforcement uses race to profile suspects. This use of racial categories is frequently criticized for perpetuating an outmoded understanding of human biological variation, and promoting stereotypes. Because in some societies racial groupings correspond closely with patterns of social stratification, for social scientists studying social inequality, race can be a significant variable. As sociological factors, racial categories may in part reflect subjective attributions, self-identities, and social institutions.[41][42]

Scholars continue to debate the degrees to which racial categories are biologically warranted and socially constructed.[43] For example, in 2008, John Hartigan, Jr. argued for a view of race that focused primarily on culture, but which does not ignore the potential relevance of biology or genetics.[44] Accordingly, the racial paradigms employed in different disciplines vary in their emphasis on biological reduction as contrasted with societal construction.

In the social sciences, theoretical frameworks such as racial formation theory and critical race theory investigate implications of race as social construction by exploring how the images, ideas and assumptions of race are expressed in everyday life. A large body of scholarship has traced the relationships between the historical, social production of race in legal and criminal language, and their effects on the policing and disproportionate incarceration of certain groups.

Groups of humans have always identified themselves as distinct from neighboring groups, but such differences have not always been understood to be natural, immutable and global. These features are the distinguishing features of how the concept of race is used today. In this way the idea of race as we understand it today came about during the historical process of exploration and conquest which brought Europeans into contact with groups from different continents, and of the ideology of classification and typology found in the natural sciences.[45] The term race was often used in a general biological taxonomic sense,[24] starting from the 19th century, to denote genetically differentiated human populations defined by phenotype.[46][47]

The modern concept of race emerged as a product of the colonial enterprises of European powers from the 16th to 18th centuries which identified race in terms of skin color and physical differences. Author Rebecca F. Kennedy argues that the Greeks and Romans would have found such concepts confusing in relation to their own systems of classification.[48] According to Bancel et al., the epistemological moment where the modern concept of race was invented and rationalized lies somewhere between 1730 and 1790.[49]

According to Smedley and Marks the European concept of "race", along with many of the ideas now associated with the term, arose at the time of the scientific revolution, which introduced and privileged the study of natural kinds, and the age of European imperialism and colonization which established political relations between Europeans and peoples with distinct cultural and political traditions.[45][50] As Europeans encountered people from different parts of the world, they speculated about the physical, social, and cultural differences among various human groups. The rise of the Atlantic slave trade, which gradually displaced an earlier trade in slaves from throughout the world, created a further incentive to categorize human groups in order to justify the subordination of African slaves.[51]

Drawing on sources from classical antiquity and upon their own internal interactions for example, the hostility between the English and Irish powerfully influenced early European thinking about the differences between people[52] Europeans began to sort themselves and others into groups based on physical appearance, and to attribute to individuals belonging to these groups behaviors and capacities which were claimed to be deeply ingrained. A set of folk beliefs took hold that linked inherited physical differences between groups to inherited intellectual, behavioral, and moral qualities.[53] Similar ideas can be found in other cultures,[54] for example in China, where a concept often translated as "race" was associated with supposed common descent from the Yellow Emperor, and used to stress the unity of ethnic groups in China. Brutal conflicts between ethnic groups have existed throughout history and across the world.[55]

The first post-Graeco-Roman published classification of humans into distinct races seems to be Franois Bernier's Nouvelle division de la terre par les diffrents espces ou races qui l'habitent ("New division of Earth by the different species or races which inhabit it"), published in 1684.[56] In the 18th century the differences among human groups became a focus of scientific investigation. But the scientific classification of phenotypic variation was frequently coupled with racist ideas about innate predispositions of different groups, always attributing the most desirable features to the White, European race and arranging the other races along a continuum of progressively undesirable attributes. The 1735 classification of Carl Linnaeus, inventor of zoological taxonomy, divided the human species Homo sapiens into continental varieties of europaeus, asiaticus, americanus, and afer, each associated with a different humour: sanguine, melancholic, choleric, and phlegmatic, respectively.[57] Homo sapiens europaeus was described as active, acute, and adventurous, whereas Homo sapiens afer was said to be crafty, lazy, and careless.[59]

The 1775 treatise "The Natural Varieties of Mankind", by Johann Friedrich Blumenbach proposed five major divisions: the Caucasoid race, the Mongoloid race, the Ethiopian race (later termed Negroid), the American Indian race, and the Malayan race, but he did not propose any hierarchy among the races.[59] Blumenbach also noted the graded transition in appearances from one group to adjacent groups and suggested that "one variety of mankind does so sensibly pass into the other, that you cannot mark out the limits between them".[60]

From the 17th through 19th centuries, the merging of folk beliefs about group differences with scientific explanations of those differences produced what Smedley has called an "ideology of race".[50] According to this ideology, races are primordial, natural, enduring and distinct. It was further argued that some groups may be the result of mixture between formerly distinct populations, but that careful study could distinguish the ancestral races that had combined to produce admixed groups.[55] Subsequent influential classifications by Georges Buffon, Petrus Camper and Christoph Meiners all classified "Negros" as inferior to Europeans.[59] In the United States the racial theories of Thomas Jefferson were influential. He saw Africans as inferior to Whites especially in regards to their intellect, and imbued with unnatural sexual appetites, but described Native Americans as equals to whites.[61]

In the last two decades of the 18th century, the theory of polygenism, the belief that different races had evolved separately in each continent and shared no common ancestor,[62] was advocated in England by historian Edward Long and anatomist Charles White, in Germany by ethnographers Christoph Meiners and Georg Forster, and in France by Julien-Joseph Virey. In the US, Samuel George Morton, Josiah Nott and Louis Agassiz promoted this theory in the mid-19th century. Polygenism was popular and most widespread in the 19th century, culminating in the founding of the Anthropological Society of London (1863), which, during the period of the American Civil War, broke away from the Ethnological Society of London and its monogenic stance, their underlined difference lying, relevantly, in the so-called "Negro question": a substantial racist view by the former,[63] and a more liberal view on race by the latter.[64]

Today, all humans are classified as belonging to the species Homo sapiens. However, this is not the first species of homininae: the first species of genus Homo, Homo habilis, evolved in East Africa at least 2 million years ago, and members of this species populated different parts of Africa in a relatively short time. Homo erectus evolved more than 1.8 million years ago, and by 1.5 million years ago had spread throughout Europe and Asia. Virtually all physical anthropologists agree that Archaic Homo sapiens (A group including the possible species H. heidelbergensis, H. rhodesiensis and H. neanderthalensis) evolved out of African Homo erectus (sensu lato) or Homo ergaster.[65][66] Anthropologists support the idea that anatomically modern humans (Homo sapiens) evolved in North or East Africa from an archaic human species such as H. heidelbergensis and then migrated out of Africa, mixing with and replacing H. heidelbergensis and H. neanderthalensis populations throughout Europe and Asia, and H. rhodesiensis populations in Sub-Saharan Africa (a combination of the Out of Africa and Multiregional models).[67][verification needed]

In the early 20th century, many anthropologists taught that race was an entirely biological phenomenon and that this was core to a person's behavior and identity, a position commonly called racial essentialism.[68] This, coupled with a belief that linguistic, cultural, and social groups fundamentally existed along racial lines, formed the basis of what is now called scientific racism.[69] After the Nazi eugenics program, along with the rise of anti-colonial movements, racial essentialism lost widespread popularity.[70] New studies of culture and the fledgling field of population genetics undermined the scientific standing of racial essentialism, leading race anthropologists to revise their conclusions about the sources of phenotypic variation.[68] A significant number of modern anthropologists and biologists in the West came to view race as an invalid genetic or biological designation.[71]

The first to challenge the concept of race on empirical grounds were the anthropologists Franz Boas, who provided evidence of phenotypic plasticity due to environmental factors,[72] and Ashley Montagu, who relied on evidence from genetics.[73] E. O. Wilson then challenged the concept from the perspective of general animal systematics, and further rejected the claim that "races" were equivalent to "subspecies".[74]

Human genetic variation is predominantly within races, continuous, and complex in structure, which is inconsistent with the concept of genetic human races.[75] According to the biological anthropologist Jonathan Marks,[45]

By the 1970s, it had become clear that (1) most human differences were cultural; (2) what was not cultural was principally polymorphic that is to say, found in diverse groups of people at different frequencies; (3) what was not cultural or polymorphic was principally clinal that is to say, gradually variable over geography; and (4) what was left the component of human diversity that was not cultural, polymorphic, or clinal was very small.

A consensus consequently developed among anthropologists and geneticists that race as the previous generation had known it as largely discrete, geographically distinct, gene pools did not exist.

The term race in biology is used with caution because it can be ambiguous. Generally, when it is used it is effectively a synonym of subspecies.[76] (For animals, the only taxonomic unit below the species level is usually the subspecies;[77] there are narrower infraspecific ranks in botany, and race does not correspond directly with any of them.) Traditionally, subspecies are seen as geographically isolated and genetically differentiated populations.[78] Studies of human genetic variation show that human populations are not geographically isolated,[79] and their genetic differences are far smaller than those among comparable subspecies.[80]

In 1978, Sewall Wright suggested that human populations that have long inhabited separated parts of the world should, in general, be considered different subspecies by the criterion that most individuals of such populations can be allocated correctly by inspection. Wright argued that, "It does not require a trained anthropologist to classify an array of Englishmen, West Africans, and Chinese with 100% accuracy by features, skin color, and type of hair despite so much variability within each of these groups that every individual can easily be distinguished from every other."[81] While in practice subspecies are often defined by easily observable physical appearance, there is not necessarily any evolutionary significance to these observed differences, so this form of classification has become less acceptable to evolutionary biologists.[82] Likewise this typological approach to race is generally regarded as discredited by biologists and anthropologists.[83][16]

In 2000, philosopher Robin Andreasen proposed that cladistics might be used to categorize human races biologically, and that races can be both biologically real and socially constructed.[84] Andreasen cited tree diagrams of relative genetic distances among populations published by Luigi Cavalli-Sforza as the basis for a phylogenetic tree of human races (p.661). Biological anthropologist Jonathan Marks (2008) responded by arguing that Andreasen had misinterpreted the genetic literature: "These trees are phenetic (based on similarity), rather than cladistic (based on monophyletic descent, that is from a series of unique ancestors)." Evolutionary biologist Alan Templeton (2013) argued that multiple lines of evidence falsify the idea of a phylogenetic tree structure to human genetic diversity, and confirm the presence of gene flow among populations. Marks, Templeton, and Cavalli-Sforza all conclude that genetics does not provide evidence of human races.

Previously, anthropologists Lieberman and Jackson (1995) had also critiqued the use of cladistics to support concepts of race. They argued that "the molecular and biochemical proponents of this model explicitly use racial categories in their initial grouping of samples". For example, the large and highly diverse macroethnic groups of East Indians, North Africans, and Europeans are presumptively grouped as Caucasians prior to the analysis of their DNA variation. They argued that this a priori grouping limits and skews interpretations, obscures other lineage relationships, deemphasizes the impact of more immediate clinal environmental factors on genomic diversity, and can cloud our understanding of the true patterns of affinity.[87]

In 2015, Keith Hunley, Graciela Cabana, and Jeffrey Long analyzed the Human Genome Diversity Project sample of 1,037 individuals in 52 populations,[88] finding that diversity among non-African populations is the result of a serial founder effect process, with non-African populations as a whole nested among African populations, that "some African populations are equally related to other African populations and to non-African populations," and that "outside of Africa, regional groupings of populations are nested inside one another, and many of them are not monophyletic."[88] Earlier research had also suggested that there has always been considerable gene flow between human populations, meaning that human population groups are not monophyletic.[78] Rachel Caspari has argued that, since no groups currently regarded as races are monophyletic, by definition none of these groups can be clades.

One crucial innovation in reconceptualizing genotypic and phenotypic variation was the anthropologist C. Loring Brace's observation that such variations, insofar as it is affected by natural selection, slow migration, or genetic drift, are distributed along geographic gradations or clines.[90] For example, with respect to skin color in Europe and Africa, Brace writes:

To this day, skin color grades by imperceptible means from Europe southward around the eastern end of the Mediterranean and up the Nile into Africa. From one end of this range to the other, there is no hint of a skin color boundary, and yet the spectrum runs from the lightest in the world at the northern edge to as dark as it is possible for humans to be at the equator.

In part this is due to isolation by distance. This point called attention to a problem common to phenotype-based descriptions of races (for example, those based on hair texture and skin color): they ignore a host of other similarities and differences (for example, blood type) that do not correlate highly with the markers for race. Thus, anthropologist Frank Livingstone's conclusion, that since clines cross racial boundaries, "there are no races, only clines".[92]

In a response to Livingstone, Theodore Dobzhansky argued that when talking about race one must be attentive to how the term is being used: "I agree with Dr. Livingstone that if races have to be 'discrete units', then there are no races, and if 'race' is used as an 'explanation' of the human variability, rather than vice versa, then the explanation is invalid." He further argued that one could use the term race if one distinguished between "race differences" and "the race concept". The former refers to any distinction in gene frequencies between populations; the latter is "a matter of judgment". He further observed that even when there is clinal variation, "Race differences are objectively ascertainable biological phenomena... but it does not follow that racially distinct populations must be given racial (or subspecific) labels."[92] In short, Livingstone and Dobzhansky agree that there are genetic differences among human beings; they also agree that the use of the race concept to classify people, and how the race concept is used, is a matter of social convention. They differ on whether the race concept remains a meaningful and useful social convention.

Skin color (above) and blood type B (below) are nonconcordant traits since their geographical distribution is not similar.

In 1964, the biologists Paul Ehrlich and Holm pointed out cases where two or more clines are distributed discordantly for example, melanin is distributed in a decreasing pattern from the equator north and south; frequencies for the haplotype for beta-S hemoglobin, on the other hand, radiate out of specific geographical points in Africa.[93] As the anthropologists Leonard Lieberman and Fatimah Linda Jackson observed, "Discordant patterns of heterogeneity falsify any description of a population as if it were genotypically or even phenotypically homogeneous".[87]

Patterns such as those seen in human physical and genetic variation as described above, have led to the consequence that the number and geographic location of any described races is highly dependent on the importance attributed to, and quantity of, the traits considered. A skin-lightening mutation, estimated to have occurred 20,000 to 50,000 years ago, partially accounts for the appearance of light skin in people who migrated out of Africa northward into what is now Europe. East Asians owe their relatively light skin to different mutations.[94] On the other hand, the greater the number of traits (or alleles) considered, the more subdivisions of humanity are detected, since traits and gene frequencies do not always correspond to the same geographical location. Or as Ossorio & Duster (2005) put it:

Anthropologists long ago discovered that humans' physical traits vary gradually, with groups that are close geographic neighbors being more similar than groups that are geographically separated. This pattern of variation, known as clinal variation, is also observed for many alleles that vary from one human group to another. Another observation is that traits or alleles that vary from one group to another do not vary at the same rate. This pattern is referred to as nonconcordant variation. Because the variation of physical traits is clinal and nonconcordant, anthropologists of the late 19th and early 20th centuries discovered that the more traits and the more human groups they measured, the fewer discrete differences they observed among races and the more categories they had to create to classify human beings. The number of races observed expanded to the 1930s and 1950s, and eventually anthropologists concluded that there were no discrete races.[95] Twentieth and 21st century biomedical researchers have discovered this same feature when evaluating human variation at the level of alleles and allele frequencies. Nature has not created four or five distinct, nonoverlapping genetic groups of people.

Another way to look at differences between populations is to measure genetic differences rather than physical differences between groups. The mid-20th-century anthropologist William C. Boyd defined race as: "A population which differs significantly from other populations in regard to the frequency of one or more of the genes it possesses. It is an arbitrary matter which, and how many, gene loci we choose to consider as a significant 'constellation'".[96] Leonard Lieberman and Rodney Kirk have pointed out that "the paramount weakness of this statement is that if one gene can distinguish races then the number of races is as numerous as the number of human couples reproducing."[97] Moreover, the anthropologist Stephen Molnar has suggested that the discordance of clines inevitably results in a multiplication of races that renders the concept itself useless.[98] The Human Genome Project states "People who have lived in the same geographic region for many generations may have some alleles in common, but no allele will be found in all members of one population and in no members of any other."[99] Massimo Pigliucci and Jonathan Kaplan argue that human races do exist, and that they correspond to the genetic classification of ecotypes, but that real human races do not correspond very much, if at all, to folk racial categories.[100] In contrast, Walsh & Yun reviewed the literature in 2011 and reported that "Genetic studies using very few chromosomal loci find that genetic polymorphisms divide human populations into clusters with almost 100 percent accuracy and that they correspond to the traditional anthropological categories."[101]

Some biologists argue that racial categories correlate with biological traits (e.g. phenotype), and that certain genetic markers have varying frequencies among human populations, some of which correspond more or less to traditional racial groupings.

The distribution of genetic variants within and among human populations are impossible to describe succinctly because of the difficulty of defining a population, the clinal nature of variation, and heterogeneity across the genome (Long and Kittles 2003). In general, however, an average of 85% of statistical genetic variation exists within local populations, 7% is between local populations within the same continent, and 8% of variation occurs between large groups living on different continents.[104] The recent African origin theory for humans would predict that in Africa there exists a great deal more diversity than elsewhere and that diversity should decrease the further from Africa a population is sampled. Hence, the 85% average figure is misleading: Long and Kittles find that rather than 85% of human genetic diversity existing in all human populations, about 100% of human diversity exists in a single African population, whereas only about 60% of human genetic diversity exists in the least diverse population they analyzed (the Surui, a population derived from New Guinea). Statistical analysis that takes this difference into account confirms previous findings that, "Western-based racial classifications have no taxonomic significance."[88]

A 2002 study of random biallelic genetic loci found little to no evidence that humans were divided into distinct biological groups.[106]

In his 2003 paper, "Human Genetic Diversity: Lewontin's Fallacy", A. W. F. Edwards argued that rather than using a locus-by-locus analysis of variation to derive taxonomy, it is possible to construct a human classification system based on characteristic genetic patterns, or clusters inferred from multilocus genetic data.[107][108] Geographically based human studies since have shown that such genetic clusters can be derived from analyzing of a large number of loci which can assort individuals sampled into groups analogous to traditional continental racial groups.[109] Joanna Mountain and Neil Risch cautioned that while genetic clusters may one day be shown to correspond to phenotypic variations between groups, such assumptions were premature as the relationship between genes and complex traits remains poorly understood.[111] However, Risch denied such limitations render the analysis useless: "Perhaps just using someone's actual birth year is not a very good way of measuring age. Does that mean we should throw it out? ... Any category you come up with is going to be imperfect, but that doesn't preclude you from using it or the fact that it has utility."[112]

Early human genetic cluster analysis studies were conducted with samples taken from ancestral population groups living at extreme geographic distances from each other. It was thought that such large geographic distances would maximize the genetic variation between the groups sampled in the analysis, and thus maximize the probability of finding cluster patterns unique to each group. In light of the historically recent acceleration of human migration (and correspondingly, human gene flow) on a global scale, further studies were conducted to judge the degree to which genetic cluster analysis can pattern ancestrally identified groups as well as geographically separated groups. One such study looked at a large multiethnic population in the United States, and "detected only modest genetic differentiation between different current geographic locales within each race/ethnicity group. Thus, ancient geographic ancestry, which is highly correlated with self-identified race/ethnicity as opposed to current residence is the major determinant of genetic structure in the U.S. population."

Witherspoon et al. (2007) have argued that even when individuals can be reliably assigned to specific population groups, it may still be possible for two randomly chosen individuals from different populations/clusters to be more similar to each other than to a randomly chosen member of their own cluster. They found that many thousands of genetic markers had to be used in order for the answer to the question "How often is a pair of individuals from one population genetically more dissimilar than two individuals chosen from two different populations?" to be "never". This assumed three population groups separated by large geographic ranges (European, African and East Asian). The entire world population is much more complex and studying an increasing number of groups would require an increasing number of markers for the same answer. The authors conclude that "caution should be used when using geographic or genetic ancestry to make inferences about individual phenotypes."[113] Witherspoon, et al. concluded that, "The fact that, given enough genetic data, individuals can be correctly assigned to their populations of origin is compatible with the observation that most human genetic variation is found within populations, not between them. It is also compatible with our nding that, even when the most distinct populations are considered and hundreds of loci are used, individuals are frequently more similar to members of other populations than to members of their own population."[113]

Anthropologists such as C. Loring Brace,[114] the philosophers Jonathan Kaplan and Rasmus Winther,[115][116][117] and the geneticist Joseph Graves,[21] have argued that while there it is certainly possible to find biological and genetic variation that corresponds roughly to the groupings normally defined as "continental races", this is true for almost all geographically distinct populations. The cluster structure of the genetic data is therefore dependent on the initial hypotheses of the researcher and the populations sampled. When one samples continental groups, the clusters become continental; if one had chosen other sampling patterns, the clustering would be different. Weiss and Fullerton have noted that if one sampled only Icelanders, Mayans and Maoris, three distinct clusters would form and all other populations could be described as being clinally composed of admixtures of Maori, Icelandic and Mayan genetic materials.[119] Kaplan and Winther therefore argue that, seen in this way, both Lewontin and Edwards are right in their arguments. They conclude that while racial groups are characterized by different allele frequencies, this does not mean that racial classification is a natural taxonomy of the human species, because multiple other genetic patterns can be found in human populations that crosscut racial distinctions. Moreover, the genomic data underdetermines whether one wishes to see subdivisions (i.e., splitters) or a continuum (i.e., lumpers). Under Kaplan and Winther's view, racial groupings are objective social constructions (see Mills 1998[120]) that have conventional biological reality only insofar as the categories are chosen and constructed for pragmatic scientific reasons. In earlier work, Winther had identified "diversity partitioning" and "clustering analysis" as two separate methodologies, with distinct questions, assumptions, and protocols. Each is also associated with opposing ontological consequences vis-a-vis the metaphysics of race.[121] Philosopher Lisa Gannett has argued that biogeographical ancestry, a concept devised by Mark Shriver and Tony Frudakis, is not an objective measure of the biological aspects of race as Shriver and Frudakis claim it is. She argues that it is actually just a "local category shaped by the U.S. context of its production, especially the forensic aim of being able to predict the race or ethnicity of an unknown suspect based on DNA found at the crime scene."[122]

Recent studies of human genetic clustering have included a debate over how genetic variation is organized, with clusters and clines as the main possible orderings.Serre & Pbo (2004) argued for smooth, clinal genetic variation in ancestral populations even in regions previously considered racially homogeneous, with the apparent gaps turning out to be artifacts of sampling techniques.Rosenberg et al. (2005) disputed this and offered an analysis of the Human Genetic Diversity Panel showing that there were small discontinuities in the smooth genetic variation for ancestral populations at the location of geographic barriers such as the Sahara, the Oceans, and the Himalayas. Nonetheless,Rosenberg et al. (2005) stated that their findings "should not be taken as evidence of our support of any particular concept of biological race... Genetic differences among human populations derive mainly from gradations in allele frequencies rather than from distinctive 'diagnostic' genotypes." Using a sample of 40 populations distributed roughly evenly across the Earth's land surface,Xing & et al. (2010, p.208) found that "genetic diversity is distributed in a more clinal pattern when more geographically intermediate populations are sampled."

Guido Barbujani has written that human genetic variation is generally distributed continuously in gradients across much of Earth, and that there is no evidence that genetic boundaries between human populations exist as would be necessary for human races to exist.

Over time, human genetic variation has formed a nested structure that is inconsistent with the concept of races that have evolved independently of one another.[124]

As anthropologists and other evolutionary scientists have shifted away from the language of race to the term population to talk about genetic differences, historians, cultural anthropologists and other social scientists re-conceptualized the term "race" as a cultural category or identity, i.e., a way among many possible ways in which a society chooses to divide its members into categories.

Many social scientists have replaced the word race with the word "ethnicity" to refer to self-identifying groups based on beliefs concerning shared culture, ancestry and history. Alongside empirical and conceptual problems with "race", following the Second World War, evolutionary and social scientists were acutely aware of how beliefs about race had been used to justify discrimination, apartheid, slavery, and genocide. This questioning gained momentum in the 1960s during the civil rights movement in the United States and the emergence of numerous anti-colonial movements worldwide. They thus came to believe that race itself is a social construct, a concept that was believed to correspond to an objective reality but which was believed in because of its social functions.[125]

Craig Venter and Francis Collins of the National Institute of Health jointly made the announcement of the mapping of the human genome in 2000. Upon examining the data from the genome mapping, Venter realized that although the genetic variation within the human species is on the order of 13% (instead of the previously assumed 1%), the types of variations do not support notion of genetically defined races. Venter said, "Race is a social concept. It's not a scientific one. There are no bright lines (that would stand out), if we could compare all the sequenced genomes of everyone on the planet." "When we try to apply science to try to sort out these social differences, it all falls apart."[126]

Anthropologist Stephan Palmi has argued that race "is not a thing but a social relation"; or, in the words of Katya Gibel Mevorach, "a metonym", "a human invention whose criteria for differentiation are neither universal nor fixed but have always been used to manage difference." As such, the use of the term "race" itself must be analyzed. Moreover, they argue that biology will not explain why or how people use the idea of race; only history and social relationships will.

Imani Perry has argued that race "is produced by social arrangements and political decision making",[129] and that "race is something that happens, rather than something that is. It is dynamic, but it holds no objective truth."[130] Similarly, Racial Culture: A Critique (2005), Richard T. Ford argued that while "there is no necessary correspondence between the ascribed identity of race and one's culture or personal sense of self" and "group difference is not intrinsic to members of social groups but rather contingent o[n] the social practices of group identification", the social practices of identity politics may coerce individuals into the "compulsory" enactment of "prewritten racial scripts".[131]

Compared to 19th-century United States, 20th-century Brazil was characterized by a perceived relative absence of sharply defined racial groups. According to anthropologist Marvin Harris, this pattern reflects a different history and different social relations.

Race in Brazil was "biologized", but in a way that recognized the difference between ancestry (which determines genotype) and phenotypic differences. There, racial identity was not governed by rigid descent rule, such as the one-drop rule, as it was in the United States. A Brazilian child was never automatically identified with the racial type of one or both parents, nor were there only a very limited number of categories to choose from,[132] to the extent that full siblings can pertain to different racial groups.[133]

Over a dozen racial categories would be recognized in conformity with all the possible combinations of hair color, hair texture, eye color, and skin color. These types grade into each other like the colors of the spectrum, and not one category stands significantly isolated from the rest. That is, race referred preferentially to appearance, not heredity, and appearance is a poor indication of ancestry, because only a few genes are responsible for someone's skin color and traits: a person who is considered white may have more African ancestry than a person who is considered black, and the reverse can be also true about European ancestry.[135] The complexity of racial classifications in Brazil reflects the extent of genetic mixing in Brazilian society, a society that remains highly, but not strictly, stratified along color lines. These socioeconomic factors are also significant to the limits of racial lines, because a minority of pardos, or brown people, are likely to start declaring themselves white or black if socially upward,[136] and being seen as relatively "whiter" as their perceived social status increases (much as in other regions of Latin America).[137]

Fluidity of racial categories aside, the "biologification" of race in Brazil referred above would match contemporary concepts of race in the United States quite closely, though, if Brazilians are supposed to choose their race as one among, Asian and Indigenous apart, three IBGE's census categories. While assimilated Amerindians and people with very high quantities of Amerindian ancestry are usually grouped as caboclos, a subgroup of pardos which roughly translates as both mestizo and hillbilly, for those of lower quantity of Amerindian descent a higher European genetic contribution is expected to be grouped as a pardo. In several genetic tests, people with less than 60-65% of European descent and 510% of Amerindian descent usually cluster with Afro-Brazilians (as reported by the individuals), or 6.9% of the population, and those with about 45% or more of Subsaharan contribution most times do so (in average, Afro-Brazilian DNA was reported to be about 50% Subsaharan African, 37% European and 13% Amerindian).[138][139][140][141]

If a more consistent report with the genetic groups in the gradation of genetic mixing is to be considered (e.g. that would not cluster people with a balanced degree of African and non-African ancestry in the black group instead of the multiracial one, unlike elsewhere in Latin America where people of high quantity of African descent tend to classify themselves as mixed), more people would report themselves as white and pardo in Brazil (47.7% and 42.4% of the population as of 2010, respectively), because by research its population is believed to have between 65 and 80% of autosomal European ancestry, in average (also >35% of European mt-DNA and >95% of European Y-DNA).[138][144][145][146]

From the last decades of the Empire until the 1950s, the proportion of the white population increased significantly while Brazil welcomed 5.5 million immigrants between 1821 and 1932, not much behind its neighbor Argentina with 6.4 million,[147] and it received more European immigrants in its colonial history than the United States. Between 1500 and 1760, 700.000 Europeans settled in Brazil, while 530.000 Europeans settled in the United States for the same given time.[148] Thus, the historical construction of race in Brazilian society dealt primarily with gradations between persons of majority European ancestry and little minority groups with otherwise lower quantity therefrom in recent times.

According to the Council of the European Union:

The European Union rejects theories which attempt to determine the existence of separate human races.

The European Union uses the terms racial origin and ethnic origin synonymously in its documents and according to it "the use of the term 'racial origin' in this directive does not imply an acceptance of such [racial] theories".[149][150][full citation needed] Haney Lpez[who?] warns that using "race" as a category within the law tends to legitimize its existence in the popular imagination. In the diverse geographic context of Europe, ethnicity and ethnic origin are arguably more resonant and are less encumbered by the ideological baggage associated with "race". In European context, historical resonance of "race" underscores its problematic nature. In some states, it is strongly associated with laws promulgated by the Nazi and Fascist governments in Europe during the 1930s and 1940s. Indeed, in 1996, the European Parliament adopted a resolution stating that "the term should therefore be avoided in all official texts".[151]

The concept of racial origin relies on the notion that human beings can be separated into biologically distinct "races", an idea generally rejected by the scientific community. Since all human beings belong to the same species, the ECRI (European Commission against Racism and Intolerance) rejects theories based on the existence of different "races". However, in its Recommendation ECRI uses this term in order to ensure that those persons who are generally and erroneously perceived as belonging to "another race" are not excluded from the protection provided for by the legislation. The law claims to reject the existence of "race", yet penalize situations where someone is treated less favourably on this ground.[151]

The immigrants to the United States came from every region of Europe, Africa, and Asia. They mixed among themselves and with the indigenous inhabitants of the continent. In the United States most people who self-identify as African American have some European ancestors, while many people who identify as European American have some African or Amerindian ancestors.

Since the early history of the United States, Amerindians, African Americans, and European Americans have been classified as belonging to different races. Efforts to track mixing between groups led to a proliferation of categories, such as mulatto and octoroon. The criteria for membership in these races diverged in the late 19th century. During the Reconstruction era, increasing numbers of Americans began to consider anyone with "one drop" of known "Black blood" to be Black, regardless of appearance. By the early 20th century, this notion was made statutory in many states. Amerindians continue to be defined by a certain percentage of "Indian blood" (called blood quantum). To be White one had to have perceived "pure" White ancestry. The one-drop rule or hypodescent rule refers to the convention of defining a person as racially black if he or she has any known African ancestry. This rule meant that those that were mixed race but with some discernible African ancestry were defined as black. The one-drop rule is specific to not only those with African ancestry but to the United States, making it a particularly African-American experience.[152]

The decennial censuses conducted since 1790 in the United States created an incentive to establish racial categories and fit people into these categories.[153]

The term "Hispanic" as an ethnonym emerged in the 20th century with the rise of migration of laborers from the Spanish-speaking countries of Latin America to the United States. Today, the word "Latino" is often used as a synonym for "Hispanic". The definitions of both terms are non-race specific, and include people who consider themselves to be of distinct races (Black, White, Amerindian, Asian, and mixed groups).[154] However, there is a common misconception in the US that Hispanic/Latino is a race[155] or sometimes even that national origins such as Mexican, Cuban, Colombian, Salvadoran, etc. are races. In contrast to "Latino" or "Hispanic", "Anglo" refers to non-Hispanic White Americans or non-Hispanic European Americans, most of whom speak the English language but are not necessarily of English descent.

The concept of race classification in physical anthropology lost credibility around the 1960s and is now considered untenable.[156][158] A 2019 statement by the American Association of Physical Anthropologists declares:

Race does not provide an accurate representation of human biological variation. It was never accurate in the past, and it remains inaccurate when referencing contemporary human populations. Humans are not divided biologically into distinct continental types or racial genetic clusters. Instead, the Western concept of race must be understood as a classification system that emerged from, and in support of, European colonialism, oppression, and discrimination.[83]

Wagner et al. (2017) surveyed 3,286 American anthropologists' views on race and genetics, including both cultural and biological anthropologists. They found a consensus among them that biological races do not exist in humans, but that race does exist insofar as the social experiences of members of different races can have significant effects on health.[159]

Wang, trkalj et al. (2003) examined the use of race as a biological concept in research papers published in China's only biological anthropology journal, Acta Anthropologica Sinica. The study showed that the race concept was widely used among Chinese anthropologists.[160] In a 2007 review paper, trkalj suggested that the stark contrast of the racial approach between the United States and China was due to the fact that race is a factor for social cohesion among the ethnically diverse people of China, whereas "race" is a very sensitive issue in America and the racial approach is considered to undermine social cohesion with the result that in the socio-political context of US academics scientists are encouraged not to use racial categories, whereas in China they are encouraged to use them.[162]

Lieberman et al. in a 2004 study researched the acceptance of race as a concept among anthropologists in the United States, Canada, the Spanish speaking areas, Europe, Russia and China. Rejection of race ranged from high to low, with the highest rejection rate in the United States and Canada, a moderate rejection rate in Europe, and the lowest rejection rate in Russia and China. Methods used in the studies reported included questionnaires and content analysis.[20]

Kaszycka et al. (2009) in 20022003 surveyed European anthropologists' opinions toward the biological race concept. Three factors, country of academic education, discipline, and age, were found to be significant in differentiating the replies. Those educated in Western Europe, physical anthropologists, and middle-aged persons rejected race more frequently than those educated in Eastern Europe, people in other branches of science, and those from both younger and older generations." The survey shows that the views on race are sociopolitically (ideologically) influenced and highly dependent on education."[163]

Since the second half of the 20th century, physical anthropology in the United States has moved away from a typological understanding of human biological diversity towards a genomic and population-based perspective. Anthropologists have tended to understand race as a social classification of humans based on phenotype and ancestry as well as cultural factors, as the concept is understood in the social sciences. Since 1932, an increasing number of college textbooks introducing physical anthropology have rejected race as a valid concept: from 1932 to 1976, only seven out of thirty-two rejected race; from 1975 to 1984, thirteen out of thirty-three rejected race; from 1985 to 1993, thirteen out of nineteen rejected race. According to one academic journal entry, where 78 percent of the articles in the 1931 Journal of Physical Anthropology employed these or nearly synonymous terms reflecting a bio-race paradigm, only 36 percent did so in 1965, and just 28 percent did in 1996.[164]

A 1998 "Statement on 'Race'" composed by a select committee of anthropologists and issued by the executive board of the American Anthropological Association, which they argue "represents generally the contemporary thinking and scholarly positions of a majority of anthropologists", declares:[165]

In the United States both scholars and the general public have been conditioned to viewing human races as natural and separate divisions within the human species based on visible physical differences. With the vast expansion of scientific knowledge in this century, however, it has become clear that human populations are not unambiguous, clearly demarcated, biologically distinct groups. Evidence from the analysis of genetics (e.g., DNA) indicates that most physical variation, about 94%, lies within so-called racial groups. Conventional geographic "racial" groupings differ from one another only in about 6% of their genes. This means that there is greater variation within "racial" groups than between them. In neighboring populations there is much overlapping of genes and their phenotypic (physical) expressions. Throughout history whenever different groups have come into contact, they have interbred. The continued sharing of genetic materials has maintained all of humankind as a single species. [...]With the vast expansion of scientific knowledge in this century, ... it has become clear that human populations are not unambiguous, clearly demarcated, biologically distinct groups. [...] Given what we know about the capacity of normal humans to achieve and function within any culture, we conclude that present-day inequalities between so-called "racial" groups are not consequences of their biological inheritance but products of historical and contemporary social, economic, educational, and political circumstances.

An earlier survey, conducted in 1985 (Lieberman et al. 1992), asked 1,200 American scientists how many disagree with the following proposition: "There are biological races in the species Homo sapiens." Among anthropologists, the responses were:

Lieberman's study also showed that more women reject the concept of race than men.[167]

The same survey, conducted again in 1999,[168] showed that the number of anthropologists disagreeing with the idea of biological race had risen substantially. The results were as follows:

A line of research conducted by Cartmill (1998), however, seemed to limit the scope of Lieberman's finding that there was "a significant degree of change in the status of the race concept". Goran trkalj has argued that this may be because Lieberman and collaborators had looked at all the members of the American Anthropological Association irrespective of their field of research interest, while Cartmill had looked specifically at biological anthropologists interested in human variation.[169]

In 2007, Ann Morning interviewed over 40 American biologists and anthropologists and found significant disagreements over the nature of race, with no one viewpoint holding a majority among either group. Morning also argues that a third position, "antiessentialism", which holds that race is not a useful concept for biologists, should be introduced into this debate in addition to "constructionism" and "essentialism".[170]

According to the 2000 University of Wyoming edition of a popular physical anthropology textbook, forensic anthropologists are overwhelmingly in support of the idea of the basic biological reality of human races. Forensic physical anthropologist and professor George W. Gill has said that the idea that race is only skin deep "is simply not true, as any experienced forensic anthropologist will affirm" and "Many morphological features tend to follow geographic boundaries coinciding often with climatic zones. This is not surprising since the selective forces of climate are probably the primary forces of nature that have shaped human races with regard not only to skin color and hair form but also the underlying bony structures of the nose, cheekbones, etc. (For example, more prominent noses humidify air better.)" While he can see good arguments for both sides, the complete denial of the opposing evidence "seems to stem largely from socio-political motivation and not science at all". He also states that many biological anthropologists see races as real yet "not one introductory textbook of physical anthropology even presents that perspective as a possibility. In a case as flagrant as this, we are not dealing with science but rather with blatant, politically motivated censorship".

In partial response to Gill's statement, Professor of Biological Anthropology C. Loring Brace argues that the reason laymen and biological anthropologists can determine the geographic ancestry of an individual can be explained by the fact that biological characteristics are clinally distributed across the planet, and that does not translate into the concept of race. He states:

Well, you may ask, why can't we call those regional patterns "races"? In fact, we can and do, but it does not make them coherent biological entities. "Races" defined in such a way are products of our perceptions. ... We realize that in the extremes of our transit Moscow to Nairobi, perhaps there is a major but gradual change in skin color from what we euphemistically call white to black, and that this is related to the latitudinal difference in the intensity of the ultraviolet component of sunlight. What we do not see, however, is the myriad other traits that are distributed in a fashion quite unrelated to the intensity of ultraviolet radiation. Where skin color is concerned, all the northern populations of the Old World are lighter than the long-term inhabitants near the equator. Although Europeans and Chinese are obviously different, in skin color they are closer to each other than either is to equatorial Africans. But if we test the distribution of the widely known ABO blood-group system, then Europeans and Africans are closer to each other than either is to Chinese.

The concept of "race" is still sometimes used within forensic anthropology (when analyzing skeletal remains), biomedical research, and race-based medicine.[173][174] Brace has criticized forensic anthropologists for this, arguing that they in fact should be talking about regional ancestry. He argues that while forensic anthropologists can determine that a skeletal remain comes from a person with ancestors in a specific region of Africa, categorizing that skeletal as being "black" is a socially constructed category that is only meaningful in the particular social context of the United States, and which is not itself scientifically valid.[175]

In the same 1985 survey (Lieberman et al. 1992), 16% of the surveyed biologists and 36% of the surveyed developmental psychologists disagreed with the proposition: "There are biological races in the species Homo sapiens."

The authors of the study also examined 77 college textbooks in biology and 69 in physical anthropology published between 1932 and 1989. Physical anthropology texts argued that biological races exist until the 1970s, when they began to argue that races do not exist. In contrast, biology textbooks did not undergo such a reversal but many instead dropped their discussion of race altogether. The authors attributed this to biologists trying to avoid discussing the political implications of racial classifications, and to the ongoing discussions in biology about the validity of the idea of "subspecies". The authors concluded, "The concept of race, masking the overwhelming genetic similarity of all peoples and the mosaic patterns of variation that do not correspond to racial divisions, is not only socially dysfunctional but is biologically indefensible as well (pp. 5 185 19)."(Lieberman et al. 1992, pp.31617)

A 1994 examination of 32 English sport/exercise science textbooks found that 7 (21.9%) claimed that there are biophysical differences due to race that might explain differences in sports performance, 24 (75%) did not mention nor refute the concept, and 1 (3.1%) expressed caution with the idea.[176]

In February 2001, the editors of Archives of Pediatrics and Adolescent Medicine asked "authors to not use race and ethnicity when there is no biological, scientific, or sociological reason for doing so."[177] The editors also stated that "analysis by race and ethnicity has become an analytical knee-jerk reflex."[178] Nature Genetics now ask authors to "explain why they make use of particular ethnic groups or populations, and how classification was achieved."[179]

Morning (2008) looked at high school biology textbooks during the 19522002 period and initially found a similar pattern with only 35% directly discussing race in the 198392 period from initially 92% doing so. However, this has increased somewhat after this to 43%. More indirect and brief discussions of race in the context of medical disorders have increased from none to 93% of textbooks. In general, the material on race has moved from surface traits to genetics and evolutionary history. The study argues that the textbooks' fundamental message about the existence of races has changed little.[180]

Surveying views on race in the scientific community in 2008, Morning concluded that biologists had failed to come to a clear consensus, and they often split along cultural and demographic lines. She notes, "At best, one can conclude that biologists and anthropologists now appear equally divided in their beliefs about the nature of race."[170]

Gissis (2008) examined several important American and British journals in genetics, epidemiology and medicine for their content during the 19462003 period. He wrote that "Based upon my findings I argue that the category of race only seemingly disappeared from scientific discourse after World War II and has had a fluctuating yet continuous use during the time span from 1946 to 2003, and has even become more pronounced from the early 1970s on".[181]

33 health services researchers from differing geographic regions were interviewed in a 2008 study. The researchers recognized the problems with racial and ethnic variables but the majority still believed these variables were necessary and useful.[182]

A 2010 examination of 18 widely used English anatomy textbooks found that they all represented human biological variation in superficial and outdated ways, many of them making use of the race concept in ways that were current in 1950s anthropology. The authors recommended that anatomical education should describe human anatomical variation in more detail and rely on newer research that demonstrates the inadequacies of simple racial typologies.[183]

A 2021 study that examined over 11,000 papers from 1949 to 2018 in The American Journal of Human Genetics, found that "race" was used in only 5% of papers published in the last decade, down from 22% in the first. Together with an increase in use of the terms "ethnicity," "ancestry," and location-based terms, it suggests that human geneticists have mostly abandoned the term "race."[184]

Lester Frank Ward (18411913), considered to be one of the founders of American sociology, rejected notions that there were fundamental differences that distinguished one race from another, although he acknowledged that social conditions differed dramatically by race.[185] At the turn of the 20th century, sociologists viewed the concept of race in ways that were shaped by the scientific racism of the 19th and early 20th centuries.[186] Many sociologists focused on African Americans, called Negroes at that time, and claimed that they were inferior to whites. White sociologist Charlotte Perkins Gilman (18601935), for example, used biological arguments to claim the inferiority of African Americans.[186] American sociologist Charles H. Cooley (18641929) theorized that differences among races were "natural," and that biological differences result in differences in intellectual abilities[187][185] Edward Alsworth Ross (18661951), also an important figure in the founding of American sociology, and a eugenicist, believed that whites were the superior race, and that there were essential differences in "temperament" among races.[185] In 1910, the Journal published an article by Ulysses G. Weatherly (18651940) that called for white supremacy and segregation of the races to protect racial purity.[185]

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Human Y-chromosome DNA haplogroup – Wikipedia

Posted: November 24, 2022 at 12:28 am

Human DNA groupings

In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by mutations in the non-recombining portions of DNA from the male-specific Y chromosome (called Y-DNA). Many people within a haplogroup share similar numbers of short tandem repeats (STRs) and types of mutations called single-nucleotide polymorphisms (SNPs).[2]

The human Y-chromosome accumulates roughly two mutations per generation.[3] Y-DNA haplogroups represent major branches of the Y-chromosome phylogenetic tree that share hundreds or even thousands of mutations unique to each haplogroup.

The Y-chromosomal most recent common ancestor (Y-MRCA, informally known as Y-chromosomal Adam) is the most recent common ancestor (MRCA) from whom all currently living humans are descended patrilineally. Y-chromosomal Adam is estimated to have lived roughly 236,000 years ago in Africa. By examining other bottlenecks most Eurasian men (men from populations outside of Africa) are descended from a man who lived in Africa 69,000 years ago (Haplogroup_CT). Other major bottlenecks occurred about 50,000 and 5,000 years ago and subsequently the ancestry of most Eurasian men can be traced back to four ancestors who lived 50,000 years ago, who were descendants of African (E-M168).[4][5][6][clarification needed]

Y-DNA haplogroups are defined by the presence of a series of Y-DNA SNP markers. Subclades are defined by a terminal SNP, the SNP furthest down in the Y-chromosome phylogenetic tree.[7][8] The Y Chromosome Consortium (YCC) developed a system of naming major Y-DNA haplogroups with the capital letters A through T, with further subclades named using numbers and lower case letters (YCC longhand nomenclature). YCC shorthand nomenclature names Y-DNA haplogroups and their subclades with the first letter of the major Y-DNA haplogroup followed by a dash and the name of the defining terminal SNP.[9]

Y-DNA haplogroup nomenclature is changing over time to accommodate the increasing number of SNPs being discovered and tested, and the resulting expansion of the Y-chromosome phylogenetic tree. This change in nomenclature has resulted in inconsistent nomenclature being used in different sources.[2] This inconsistency, and increasingly cumbersome longhand nomenclature, has prompted a move toward using the simpler shorthand nomenclature.

Haplogroup A is the NRY (non-recombining Y) macrohaplogroup from which all modern paternal haplogroups descend. It is sparsely distributed in Africa, being concentrated among Khoisan populations in the southwest and Nilotic populations toward the northeast in the Nile Valley. BT is a subclade of haplogroup A, more precisely of the A1b clade (A2-T in Cruciani et al. 2011), as follows:

The defining mutations separating CT (all haplogroups except for A and B) are M168 and M294. The site of origin is likely in Africa. Its age has been estimated at approximately 88,000 years old,[11][12] and more recently at around 100,000[13] or 101,000 years old.[14]

The groups descending from haplogroup F are found in some 90% of the world's population, but almost exclusively outside of sub-Saharan Africa.

FxG,H,I,J,K is rare in modern populations and peaks in South Asia, especially Sri Lanka.[10] It also appears to have long been present in South East Asia; it has been reported at rates of 45% in Sulawesi and Lembata. One study, which did not comprehensively screen for other subclades of F-M89 (including some subclades of GHIJK), found that Indonesian men with the SNP P14/PF2704 (which is equivalent to M89), comprise 1.8% of men in West Timor, 1.5% of Flores 5.4% of Lembata 2.3% of Sulawesi and 0.2% in Sumatra.[15][16] F* (FxF1,F2,F3) has been reported among 10% of males in Sri Lanka and South India, 5% in Pakistan, as well as lower levels among the Tamang people (Nepal), and in Iran. F1 (P91), F2 (M427) and F3 (M481; previously F5) are all highly rare and virtually exclusive to regions/ethnic minorities in Sri Lanka, India, Nepal, South China, Thailand, Burma, and Vietnam. In such cases, however, the possibility of misidentification is considered to be relatively high and some may belong to misidentified subclades of Haplogroup GHIJK.[17]

Haplogroup G (M201) originated some 48,000 years ago and its most recent common ancestor likely lived 26,000 years ago in the Middle East. It spread to Europe with the Neolithic Revolution.

It is found in many ethnic groups in Eurasia; most common in the Caucasus, Iran, Anatolia and the Levant. Found in almost all European countries, but most common in Gagauzia, southeastern Romania, Greece, Italy, Spain, Portugal, Tyrol, and Bohemia with highest concentrations on some Mediterranean islands; uncommon in Northern Europe.[18][19]

G-M201 is also found in small numbers in northwestern China and India, Bangladesh, Pakistan, Sri Lanka, Malaysia, and North Africa.

Haplogroup H (M69) probably emerged in South Central Asia or South Asia, about 48,000 years BP, and remains largely prevalent there in the forms of H1 (M69) and H3 (Z5857). Its sub-clades are also found in lower frequencies in Iran, Central Asia, across the middle-east, and the Arabian peninsula.

However, H2 (P96) is present in Europe since the Neolithic and H1a1 (M82) spread westward in the Medieval era with the migration of the Roma people.

Haplogroup I (M170, M258) is found mainly in Europe and the Caucasus.

Haplogroup J (M304, S6, S34, S35) is found mainly in the Middle East and South-East Europe.

Haplogroup K (M9) is spread all over Eurasia, Oceania and among Native Americans.

K(xLT,K2a,K2b) that is, K*, K2c, K2d or K2e is found mainly in Melanesia, Aboriginal Australians, India, Polynesia and Island South East Asia.

Haplogroup L (M20) is found in South Asia, Central Asia, South-West Asia, and the Mediterranean.

Haplogroup T (M184, M70, M193, M272) is found at high levels in the Horn of Africa (mainly Cushitic-speaking peoples), parts of South Asia, the Middle East, and the Mediterranean. T-M184 is also found in significant minorities of Sciaccensi, Stilfser, Egyptians, Omanis, Sephardi Jews,[20] Ibizans (Eivissencs), and Toubou. It is also found at low frequencies in other parts of the Mediterranean and South Asia.

The only living males reported to carry the basal paragroup K2* are indigenous Australians. Major studies published in 2014 and 2015 suggest that up to 27% of Aboriginal Australian males carry K2*, while others carry a subclade of K2.

Haplogroup N (M231) is found in northern Eurasia, especially among speakers of the Uralic languages.

Haplogroup N possibly originated in eastern Asia and spread both northward and westward into Siberia, being the most common group found in some Uralic-speaking peoples.

Haplogroup O (M175) is found with its highest frequency in East Asia and Southeast Asia, with lower frequencies in the South Pacific, Central Asia, South Asia, and islands in the Indian Ocean (e.g. Madagascar, the Comoros).

No examples of the basal paragroup K2b1* have been identified. Males carrying subclades of K2b1 are found primarily among Papuan peoples, Micronesian peoples, indigenous Australians, and Polynesians.

Its primary subclades are two major haplogroups:

Haplogroup P (P295) has two primary branches: P1 (P-M45) and the extremely rare P2 (P-B253).[21]

P*, P1* and P2 are found together only on the island of Luzon in the Philippines.[21] In particular, P* and P1* are found at significant rates among members of the Aeta (or Agta) people of Luzon.[22] While, P1* is now more common among living individuals in Eastern Siberia and Central Asia, it is also found at low levels in mainland South East Asia and South Asia. Considered together, these distributions tend to suggest that P* emerged from K2b in South East Asia.[22][23]

P1 is also the parent node of two primary clades:

Haplogroup Q (MEH2, M242, P36) found in Siberia and the AmericasHaplogroup R (M207, M306): found in Europe, West Asia, Central Asia, and South Asia

Q is defined by the SNP M242. It is believed to have arisen in Central Asia approximately 32,000 years ago.[24][25] The subclades of Haplogroup Q with their defining mutation(s), according to the 2008 ISOGG tree[26] are provided below. ss4 bp, rs41352448, is not represented in the ISOGG 2008 tree because it is a value for an STR. This low frequency value has been found as a novel Q lineage (Q5) in Indian populations[27]

The 2008 ISOGG tree

Haplogroup R is defined by the SNP M207. The bulk of Haplogroup R is represented in the descendant subclade R1 (M173), which likely originated on the Eurasian Steppes. R1 has two descendant subclades: R1a and R1b.

R1a is associated with the proto-Indo-Iranian and Balto-Slavic peoples, and is now found primarily in Central Asia, South Asia, and Eastern Europe.

Haplogroup R1b is the dominant haplogroup of Western Europe and is also found sparsely distributed among various peoples of Asia and Africa. Its subclade R1b1a2 (M269) is the haplogroup that is most commonly found among modern Western European populations, and has been associated with the Italo-Celtic and Germanic peoples.

This article needs to be updated. Please help update this article to reflect recent events or newly available information. (February 2021)

Footnotes

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