Posted by n/a at 12/09/2009 02:13:00 AM
The team used short-read assembly approaches to put together new Asian and African genomes, which they then compared with the current human reference sequence. The result: about five million bases of sequence not found in the reference. [. . .]
They also began applying the data to answer questions about human population and migration patterns, honing in on 164 newly detected sequences that did not overlap between the Asian and African genomes. [. . .]
While the overall pattern in these sequences was consistent with an out of Africa migration, their analyses also uncovered new patterns that couldn't be detected from mitochondrial and Y chromosome DNA studies.
For instance, they found that a sequence frequently found in the San population in southern Africa is less and less frequent in northern Africa. The frequency of this sequence apparently dwindles even more in populations outside of Africa, disappearing in European, Oceanic, and Native American populations.
In contrast, the team noted, they found a sequence that is more prominent with geographic distance from Africa. Still other sequences had less straightforward patterns, decreasing in East Asian and Oceanic populations compared with African populations but turning up again in European populations.
Along with population patterns, the genomes also provided hints about how genome sequence varies from one individual to the next. For example, while the Asian and African individuals' genomes differed by about four million bases (not including SNPs), the researchers found about a 1.8 million base difference between the Chinese genome and a preliminary Korean genome sequence assembly.