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To unravel the evolutionary history to chimpanzees, the research team collected DNA from 78 common chimpanzees and six bonobos, a separate species of chimpanzee, and examined 310 DNA markers from each. They found four “discontinuous populations.” “We saw little evidence of migration between groups in the wild,” said Celine Becquet, first author of the paper and a graduate student in Przeworski’s laboratory. “Part of that could stem from the gaps in our samples, but we think most of this separation is genuine, a long-term consequence of geographic isolation.” The original boundaries between groups may have been the emergence and growth of rivers, such as the Congo River, which is thought to be about 1.5 million years old. “Chimps don’t swim,” Becquet explained. “For them, water provides a very effective border.” An ongoing loss of habitat has increased the physical separation between the three groups.
[Note: To read the full article, click here. Photo source: John Mitani.]