The central chimpanzee sequences also appear to be the oldest of the chimpanzee lineages. According to P bo, the variation is similar to what geneticists see with the human African 'Eve'. The central chimps are the most genetically diverse and other groups seem to be derived from them. But P bo and his colleagues acknowledged that mitochondrial DNA studies, which show the most diversity in the western population, clash with this version of events. The research team encountered another curious contradiction between the mitochondrial and nuclear genomes when they drew up an evolutionary tree for their sample.
Mitochondrial studies divide the western, central, and eastern chimps into discrete groups.
By contrast, the Xq13.3 sequence tree showed that the geographical subspecies were in fact highly intermixed. According to the scientists, the disagreement could be a matter of timing. Since biologists often single out genetically unique populations like subspecies as a focus of conservation efforts, this distinction could have real-life implications for protecting endangered chimpanzees. Xq13.3 had yet another surprise up its sleeve when it came to the bond between the chimpanzee and the bonobo. Their evolutionary tree revealed a closer relationship between the two separate species than was inferred from other DNA sequences.