Indian; they then arrested a suspect who was black. The reliability of the test has not yet been established, but if it helps police identify a suspect, the suspect's DNA can then be compared with the crime scene DNA in the usual way. Feldman and his colleagues say they needed varying numbers of markers—in this case sites with tandem repeats—to identify a person's continent of origin, depending on the genetic variability of the race in question. Native Americans could be assigned to their continent of origin with just 100 markers, whereas almost all 377 markers were required to identify Middle Easterners. This is because Native Americans are all descended from their Siberian founders whereas Middle Easterners are a more complex genetic blend; they are mostly Caucasian but some, like the Bedouin, have an African contribution. Feldman's method gives a glimpse of how deeply genetic markers may be able to reach into population history. The computer program used to sort the genome samples into continental clusters could also split an individual's genome into different parts if the person was of mixed ancestry. People from the Hazara and Uighur of Central Asia, long a crossroads between east and west, emerged with genomes roughly half Caucasian and half East Asian in origin. The Surui, a fairly isolated people of Brazil, have genomes that are entirely American (in terms of the computer program's 5 racial clusters), whereas Mayan genomes are American with a strong dash of European and East Asian admixture.
With extra markers, and ones chosen to be more diagnostic of geographical origins, it should be possible to explore a population's ancestry and history in a much more detailed way. For geneticists, the essence of race is not politics but history:
race defines through which branch of the human family tree people trace their descent.
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