Final Report Summary - TWOPAN (Genomic and Phenotypic Evolution of Bonobos, Chimpanzees and Humans)
We also find that whereas chimpanzees retain genomic variation that predates bonobo-chimpanzee speciation, much of the bonobo genome traces its ancestry back to a single common ancestor that postdates their origin as a group separate from chimpanzees, suggesting that from a genomic perspective the chimpanzees are more similar to the common ancestor of the African apes than bonobos.
We have studied the behavioral and cognitive differences between the bonobos and chimpanzees, finding among other things that bonobos are more skilled at solving tasks related to social relationships, while chimpanzees were more skilled at tasks requiring the use of tools and an understanding of physical causality. To ask if the differences in social system in the two apes have affected the evolution of their genome, we sequenced the protein-coding genes of 20 chimpanzees and 20 bonobos. We find that the X chromosomes of bonobos carry a higher proportion of putatively deleterious alleles relative to the other chromosomes than chimpanzees or humans. By simulations we show that the explanation for this is likely that competition among males for mates is much less pronounced in bonobos than in chimpanzee and that mothers influence their son’s reproductive success in bonobos.
We have studied gene activity in six different tissues of apes and humans and find the evolutionary changes in gene activity have been most pronounced in the male germ line and the least pronounced in the brain. However, many genes related to the insulation of neurons from each other have changed in the ancestors of humans, perhaps playing a role in the fine-tuning of connectivity in the human brain.
We have analyzed health-related substances in the blood of 257 wild and captive-born apes and over 300 humans. This is the largest set of clinical data available from apes and will help in monitoring the health status of apes in sanctuaries as well as in the management of wild populations.