"Each microsatellite had between four and 32 distinct types," Feldman said. "Most were found in people from several continents, suggesting that only a tiny fraction of genetic traits are distinctive to specific populations. This means that visible differences between human groups such as skin color and skull shape result from differences in a very small proportion of genetic traits."
Another way to view this, he noted, is to remember that DNA is virtually identical in all human beings. Compare any two people, you'll find a DNA sequence that is about 99.9 percent identical.
"In the less than one percent of the genome where genetic differences among individuals exist, it might seem intuitive that two people from different regions are likely to have more differences than are two people from the same region," Feldman noted. "But this is not the case. About 94 percent of genetic differences are among individuals of the same populations."
The conclusion, he said, is that people from different lands have more genetic similarities than scientists previously thought.
Genetic predictors
Although populations are genetically quite similar, Feldman and his co-workers wanted to see if they could predict where an individual's ancestors came from through DNA analysis alone. To accomplish this, the research team first removed the labels from all 1,056 DNA samples used in the study.
"We took the labels off of all the individuals so we didn't know where they came from," Feldman explained. "Then we asked the question, 'Can we look at the DNA and detect where groups of individuals form clusters that are genetically related to one another?'"
The answer should be yes, Feldman predicted, because, while most genetic types are widely distrib
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
19-Dec-2002