Munch Lab

Bonobo genome shows that bonobos and chimpanzees resemble us in separate ways

Most people think that the chimpanzee alone is our closest relative, but in fact there is a second ape, the bonobo, that we are just as related to. Humans split from the other apes 5-6 million years ago and only 1-2 million years ago the ancestor to bonobos and chimpanzees split into these two species. This likely happened when the Congo river formed, separating the two species – chimpanzees and bonobos do not swim. bonobos live south of the river in the Democratic Republic of Congo.

Although darker and more slender than chimpanzees they are similar in appearance, but they Ulindidiffer strikingly from chimpanzees in social and sexual behavior. In chimpanzees the male is the dominant sex, hierarchy and conflict resolution is based on aggression. In bonobos females are dominant, hierarchy is based on mother’s status and conflicts are resolved through sex. These strikingly different behavioral characteristics have made scientists dub the bonobo “the hippie ape” and “the make love not war ape”. Our collaborators at the Max Planck Institute for Evolutionary Anthropology in Leipzig tell us that if they throw a toy into a chimpanzee cage the chimpanzees with fight over it leaving the winner to play with it alone. If it is thrown into a bonobo cage everyone will have sex and then share the toy. Several of the social and sexual traits that are only found in one of these apes are also found in humans. The frequent non-conceptive sexual behavior is thus shared with humans but not with chimpanzees, lethal aggression is found in chimpanzees and humans but not in bonobos humans and bonobos are very playful whereas chimpanzees are less so, and chimpanzees and humans apply cooperative hunting whereas bonobos do not.

Today the bonobo genome is published in Nature revealing a detailed account of our relation to bonobos and chimpanzees. The genomic DNA was obtained from the female bonobo Ulindi from Leipzig zoo while she was anesthetized anyway by the dentist. The Bioinformatics Research Centre has participated in the bonobo genome consortium and I have led an effort contributing a bioinformatic analysis of the bonobo genome, the results of which define the topic of the paper published today. The bioinformatical approach we apply is unique because it combines the analysis of genetics within species with the genetics between species, combining these two traditionally separated fields into one model.

Comparing the bonobo genome to the already known genomes of humans and chimpanzees we have shown that for some parts of the genome (about 3%) it is not bonobos and chimpanzees that are most similar but humans and bonobos or humans and chimpanzees. This patchwork of genetic relatedness results because the three species are so closely related that they may share genes inherited from the common ancestor of all three species. 25% of our protein coding genes has parts that are more similar to bonobo or chimpanzee than these are to each other. Future research may reveal if any of these genes are responsible for traits we only share with one of these apes. A candidate could be the TAAR8 gene that has a variant only shared between humans and bonobos. The gene codes for a protein receptor that is known to help mice smell amines in urine and may provide social cues in bonobos.

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