Researchers have just discovered that chimpanzees, our closest ancestors, once mated with bonobos. A recent genome analysis confirmed that there was interbreeding at a few points in time. The findings provide new insights into human evolution. The details are in a paper that was published in the journal Science.
Chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are great apes from Africa and are the closest living relatives of humans. Both species are endangered and protected by law but still regularly fall prey to poaching. This problem led scientists to perform genomic analyses in an effort to aid conservation attempts.
Researchers from the Wellcome Trust Sanger Institute, collaborating with scientists across the globe, analyzed the genomes of 75 individual chimpanzees and bonobos. The apes were wild-born and captured from locations spanning 10 different countries in Africa. The team used the genomic data to determine where individual chimps were from, allowing conservationists to release animals in the correct locations.
The research team was able to confirm that chimpanzees and bonobos separated from a common ancestor about 1.5 million years ago, as previous research had already suggested. The team’s other finding was even more interesting, however. There was gene flow between the two species only 200,000 to 550,000 years ago. Gene flow occurred again around 150,000 years ago. This means bonobos and common chimpanzees were interbreeding at two separate times during the evolution of hominids. About 1% of chimpanzee DNA is from bonobos, showing that this interbreeding had an impact on evolution.
The team’s findings change our current understanding of human evolution. Previously, it was believed that chimpanzees had separated from bonobos over a million years ago. This new study confirms that theory but also shows that the two species interbred several times throughout evolutionary history. Researchers had thought this was impossible because the apes were separated by the Congo River but genomic data proves otherwise. Mating between different great ape species may have been more common than previous research had suggested.
Manuel et al. Chimpanzee genomic diversity reveals ancient admixture with bonobos. Science (2016).