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Race classification of human beings Early racial classification attempts measured surface traitsparticularly skin color, hair color and texture, eye color, and head size and shape. Measurements of the latter through craniometry were repeatedly discredited in the late 19th and midth centuries. According to Luigi Luca Cavalli-Sforza, "From a scientific point of view, the concept of race has failed to obtain any consensus; none is likely, given the gradual variation in existence.
It may be objected that the racial stereotypes have a consistency that allows even the layman to classify individuals. However, the major stereotypes, all based on skin color, hair color and form, and facial traits, reflect superficial differences that are not confirmed by deeper analysis with Council responsible for genetics reliable genetic traits and whose origin dates from recent evolution mostly under the effect of climate and perhaps sexual selection".
Research by Ludwik and Hanka Herschfeld during World War I found that the incidence of blood groups A and B differed by region; for example, among Europeans 15 percent were group B and 40 percent group A.
Eastern Europeans and Russians had a higher incidence of group B; people from India had the greatest incidence. The Herschfelds concluded that humans comprised two "biochemical races", originating separately. It was hypothesized that these two races later mixed, resulting in the patterns of groups A and B.
This was one of the first theories of racial differences to include the idea that human variation did not correlate with genetic variation. It was expected that groups with similar proportions of blood groups would be more closely related, but instead it was often found that groups separated by great distances such as those from Madagascar and Russiahad similar incidences.
Structure[ edit ] Principal component analysis of fifty populations, color-coded by region, illustrates the differentiation and overlap of populations found using this method of analysis. Several methods to examine and quantify genetic subgroups exist, including cluster and principal components analysis.
Genetic markers from individuals are examined to find a population's genetic structure. While subgroups overlap when examining variants of one marker only, when a number of markers are examined different subgroups have different average genetic structure.
An individual may be described as belonging to several subgroups.
These subgroups may be more or less distinct, depending on how much overlap there is with other subgroups. The results obtained from cluster analyses depend on several factors: A large number genetic markers studied facilitates finding distinct clusters. AIMs can also be used to determine someone's admixture proportions.
The clustering structure obtained with different statistical techniques is similar. A similar cluster structure is found in the original sample with a subsample of the original sample. It may compare the genetic similarity of related species, such as humans and chimpanzees. Within a species, genetic distance measures divergence between subgroups.
Genetic distance significantly correlates to geographic distance between populations, a phenomenon sometimes known as " isolation by distance ". Genetic distance is measured by the fixation index FST.
FST is the correlation of randomly chosen alleles in a subgroup to a larger population. It is often expressed as a proportion of genetic diversity.
This comparison of genetic variability within and between populations is used in population genetics. The values range from 0 to 1; zero indicates the two populations are freely interbreeding, and one would indicate that two populations are separate.
Many studies place the average FST distance between human races at about 0. Henry Harpending argued that this value implies on a world scale a "kinship between two individuals of the same human population is equivalent to kinship between grandparent and grandchild or between half siblings".
In fact, the formulas derived in Harpending's paper in the 'Kinship in a subdivided population' section imply that two unrelated individuals of the same race have a higher coefficient of kinship 0. The results can be presented as maps showing genetic variation. Cavalli-Sforza and colleagues argue that if genetic variations are investigated, they often correspond to population migrations due to new sources of food, improved transportation or shifts in political power.
For example, in Europe the most significant direction of genetic variation corresponds to the spread of agriculture from the Middle East to Europe between 10, and 6, years ago.
Historic analyses use differences in genetic variation measured by genetic distance as a molecular clock indicating the evolutionary relation of species or groups, and can be used to create evolutionary trees reconstructing population separations.
There are generally shorter genetic distances between populations using languages from the same language family.The mission of the Council for Responsible Genetics (CRG) is based on the following principles: 1.
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By Jonathan Latham. The Council for Responsible Genetics (CRG) is a public interest group with a focus on biotechnology. For release 4 July The Canadian Council for Refugees (CCR), Amnesty International (AI) and the Canadian Council of Churches.
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The relationship between race and genetics is relevant to the controversy concerning race timberdesignmag.com everyday life, many societies classify populations into groups based on phenotypical traits and impressions of probable geographic ancestry and cultural identity—these are the groups usually called "races" in countries like the United States, Brazil, and South Africa.