So what is a bonobo and why are they so interesting to us? Well, as I told you earlier, bonobos are one of our two closest relatives. It's confusing cuz how can you have two close relatives where there can only be one number one, but remember this is more like a genealogy. You can have two cousins that are your first cousin, and they're equally closely related to you. But one is a girl and one is a boy. So while both are first cousins, they are different from one another and that's the case that we have with chimpanzees and bonobos. When you look at the tree of our family of apes, bonobos and chimpanzees are our closest relative and bonobos and chimpanzees are equally closely related to us. But what's really interesting is, they're very closely related to each other. And of course, the biggest surprise was when we first found out about the relationship of apes to each other, everyone thought that bonobos chimpanzees and gorillas would be more closely related to each other. But of course what we find is that the closest relative of humans. Or sorry, the closest relative of chimpanzees and bonobos is the human. So imagine when they woke up one morning and all the chimpanzees and bonobos found out they weren't closely related to gorillas, they were more closely related to us. What a shock that must have been. So, I think the most important thing about bonobos besides the fact that they're so xenophilic is that they are very different in their social structure and I think that may be part of what explains this very interesting preference for strangers. They sort of break a natural law where the bigger animal is the dominant animal. And instead the way that it works is that little Mimi here who weighs a lot less than big scary Tatango who is a big male. She's actually dominant to him. She actually is not dominated by him. He can't bully her in the way that you normally see larger animals bully smaller animals. Well how do they do that? Well they do it with girl power. They do it by, females who are all physically smaller than any male. Actually working together, cooperating, and any time a male bonobo becomes overly aggressive, as the Congolese say where they live, the females work together to correct him. And so they will actually become aggressive towards that male, and they will work together to scare him, or chase him, or even attack him so that he then will stop being so aggressive. But the result of that is you have a species that, unlike chimpanzees, our other close relative, which has a lot of problems with male aggression, it has never been witnessed that a bonobo kills another bonobo. So when you ask the question, who is the most intelligent and who is the most highly evolved? Well, the question seems really silly and funny when you have an astronaut representing the human species. And if you emphasize human technology, as our great accomplishments in terms of innovating and solving all sorts of technical challenges. Well, our close relatives bonobos and chimpanzees don't seem that intelligent. But if you remember that they're different types of intelligent then you take a cognitive approach. Well, you can't just look at one type of intelligence and decide who is the most intelligent. And humans don't look so good when you start thinking about our darker side. We obviously murder each other, we have sexual coercion where people are forced to do things that they don't want to do, there are sexual taboos, there's infanticide where humans will kill other humans because they're infants. And obviously, we have a proclivity to gamble. We've seen lots of evidence of that, whether you're talking about somebody back in Vegas or our whole economy having problems because people taking risks that didn't make sense in the long-term. So when you look at chimpanzees, they actually look just like us. They have all of these darker traits. But when we look at bonobos, even though they are our very close relative, they have none of these darker traits that we see in ourselves and chimpanzees. So then it's kind of fun to think about who is the most intelligent, and of course that's like asking what's a better tool, a hammer or a screwdriver? But I do think that what it really highlights to us is that the bonobo is really special, and it's a phenomenon we need to explain, and this is where the work with dogs comes into helping us look for an example of convergent evolution. So Oreo led me to foxes, and the foxes led me to Bonobos because what we suggested together with colleagues in a paper about the evolution of bonobos is just like the foxes and presumably like dogs, bonobos have evolved due to natural selection acting to favor male bonobos that were least aggressive. That were more interested in being pro-social. They were interested in strangers, and interested in being friendly. And not interested in displaying and doing all the darker things that our species and chimpanzees are famous for. And so it was the work with foxes leading us to understand that natural selection could potentially lead to changes, in not just behavior, but also morphology, physiology, and cognition that led us to this hypothesis. And we tested it by looking at bonobo morphology and comparing it to chimpanzees. And one of the most interesting things, is just like we see in all domesticated species, bonobos have a much smaller cranium, or brain size than chimpanzees, is about a 20% reduction. You have a much more gracile skeleton like we talked about with the foxes. They also have a more feminised physique, and they also show a whole host of developmental delays because one of the ways that we think, the foxes and even dogs evolved is with selection on aggression, slowing down the pace of development and essentially dogs are juvenileized wolves that never grow up. And that's what we think happened to bonobos is they evolved from a more chimpanzee like ancestor who had a change in how it develops. There was selection against aggression and you have a different species that is completely devoid of all the things that haunt our nature and our darker side. So what about us? Could we use what we've learned about dogs, and wolves, and foxes, and now bonobos? Cuz if it happened in a species so closely related to us, can we now think about our own species? So, in summary, convergent evolution is the process by which two distantly related species evolve the same solution to a problem independently. Bonobos are our closest genetic relatives along with chimpanzees. Bonobos never kill while chimpanzees are known to kill. Bonobo females prefer the least aggressive males in the group, and that's probably how they evolved. There's growing evidence that bonobos changed in behavior, morphology, physiology and cognition in ways that converge with other domesticated animals. And bonobos may have evolved through self-domestication which we think we have evidence for in dogs, and we think may be going on with lots of species as they repopulate urban areas, and now we can ask the question about our own species.
