Genetics | The Smithsonian Institution's Human Origins Program
The genetic relationships within the human race today (or at least of many major groups within it) has been published by L.L. Cavalli-Sforza et al, , The. PDF | In the last decades, the concept of human races was considered of continents regarded as large races have developed during long evolution from local .. Tree of genetic relatedness of a number of European populations  with their. The evolutionary relationships of human populations can be revealed only when a large . extent of gene admixture in early human evolution, our phylogenetic analysis presented Genetic relationship and evolution of human races. Evol.
The DNA evidence leaves us with one of the greatest surprises in biology: The human evolutionary tree is embedded within the great apes. The strong similarities between humans and the African great apes led Charles Darwin in to predict that Africa was the likely place where the human lineage branched off from other animals — that is, the place where the common ancestor of chimpanzees, humans, and gorillas once lived.
The DNA evidence shows an amazing confirmation of this daring prediction.
The genetic relationships of modern human races |
The African great apes, including humans, have a closer kinship bond with one another than the African apes have with orangutans or other primates. The DNA evidence informs this conclusion, and the fossils do, too. Even though Europe and Asia were scoured for early human fossils long before Africa was even thought of, ongoing fossil discoveries confirm that the first 4 million years or so of human evolutionary history took place exclusively on the African continent.
It is there that the search continues for fossils at or near the branching point of the chimpanzee and human lineages from our last common ancestor. Primate Family Tree Due to billions of years of evolution, humans share genes with all living organisms.
The percentage of genes or DNA that organisms share records their similarities. We share more genes with organisms that are more closely related to us.
However, Dawkins took issue with Lewontin's politics; and, like Edwards, Dawkins disagreed with Lewontin's conclusion that race is of "virtually no genetic or taxonomic significance", summarizing Edwards' point that however small the racial partition of the total variation may be, if such racial characteristics as there are highly correlated with other racial characteristics, they are by definition informative, and therefore of taxonomic significance.
Loring Brace philosopher Jonathan Kaplan and geneticist Joseph Graves  have argued that while it is possible to find biological and genetic variation roughly corresponding to race, this is true for almost all geographically distinct populations: When one samples continental groups, the clusters become continental; with other sampling patterns, the clusters would be different.
Evolution of human races at the gene level.
Weiss and Fullerton note that if one sampled only Icelanders, Mayans and Maoris, three distinct clusters would form; all other populations would be composed of genetic admixtures of Maori, Icelandic and Mayan material. The study found "nearly perfect correspondence between genetic cluster and SIRE for major ethnic groups living in the United States, with a discrepancy rate of only 0.
Selecting for informative genetic markers allowed a reduction to less thanwhile retaining near-total accuracy. African Americans have an estimated 10—percent European genetic admixture; Hispanics have European, Native American and African ancestry. As a result, skin color differences within the population are not gradual, and there's relatively weak associations between self-reported race and African ancestry. Genetic distances generally increase continually with geographic distance, which makes a dividing line arbitrary.
Any two neighboring settlements will exhibit some genetic difference from each other, which could be defined as a race.
Therefore, attempts to classify races impose an artificial discontinuity on a naturally occurring phenomenon. This explains why studies on population genetic structure yield varying results, depending on methodology. Thus, analysis of the locus dataset corroborates our earlier results: However, for pairs from different clusters, genetic distance is generally larger than that between intracluster pairs that have the same geographic distance.
For example, genetic distances for population pairs with one population in Eurasia and the other in East Asia are greater than those for pairs at equivalent geographic distance within Eurasia or within East Asia. Loosely speaking, it is these small discontinuous jumps in genetic distance—across oceansthe Himalayasand the Sahara —that provide the basis for the ability of STRUCTURE to identify clusters that correspond to geographic regions".
They found that many thousands of genetic markers had to be used for the answer to "How often is a pair of individuals from one population genetically more dissimilar than two individuals chosen from two different populations? This assumed three population groups, separated by large geographic distances European, African and East Asian.
The global human population is more complex, and studying a large number of groups would require an increased number of markers for the same answer. They conclude that "caution should be used when using geographic or genetic ancestry to make inferences about individual phenotypes",  and "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 finding 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". Sauer said, "the successful assignment of race to a skeletal specimen is not a vindication of the race concept, but rather a prediction that an individual, while alive was assigned to a particular socially constructed 'racial' category.
A specimen may display features that point to African ancestry. In this country that person is likely to have been labeled Black regardless of whether or not such a race actually exists in nature". Race and health There are certain statistical differences between racial groups in susceptibility to certain diseases.
The Duffy negative phenotype is highly frequent in central Africa and the frequency decreases with distance away from Central Africa, with higher frequencies in global populations with high degrees of recent African immigration. Race in the new era of human genetics research Inscientists completed the Human Genome Projectmaking it finally possible to examine human ancestry with genetics. Scientists have since tackled topics such as human migrations out of Africa and around the world.
The soaring popularity of ancestry testing bespeaks a widespread perception that we can use these tests to dissect, delineate, and define our ancestral composition.
Indeed, social media is teeming with blog posts, and even livestream videosfrom excited customers bursting to broadcast their test results and their reactions.
Race and genetics
According to this view, variation between the races is large, and thus, the each race is a separate category. Additionally, individual races are thought to have a relatively uniform genetic identity. B Actual genetic variation in humans. Human populations do roughly cluster into geographical regions. However, variation between different regions is small, thus blurring the lines between populations.
Furthermore, variation within a single region is large, and there is no uniform identity. New findings in genetics tear down old ideas about race Estimating our ancestral composition down to 0.
But reality is far less simple. A landmark study by Stanford scientists examined the question of human diversity by looking at the distribution across seven major geographical regions of 4, alleles. For instance, all humans have the same genes that code for hair: The observation that the vast majority of the alleles were shared over multiple regions, or even throughout the entire world, points to the fundamental similarity of all people around the world—an idea that has been supported by many other studies Figure 1B.
However, the Stanford study found that only 7. In fact, there is ample variation within races Figure 1B.
Ultimately, there is so much ambiguity between the races, and so much variation within them, that two people of European descent may be more genetically similar to an Asian person than they are to each other Figure 2. Case study of genetic variation between three scientists.
Schematization of the genetic variation between Drs.