In 1879, American economist Francis Walker tried to explain why members of his profession were in such "bad odor amongst real people". He blamed it o… - Frans de Waal

I first saw them in 1978. At the time, I knew a lot about chimps, because I had been studying them. I saw the bonobos at a zoo in Holland, and I thought immediately, they're totally different. The sense you get looking them in the eyes is that they're more sensitive, more sensual, not necessarily more intelligent, but there's a high emotional awareness, so to speak, of each other and also of people who look at them.

If you look at human society, it is very easy, of course, to compare our warfare and territoriality with the chimpanzee. But that's only one side of what we do. We also trade, we intermarry, we allow each other to travel through our territory. There's an enormous amount of cooperation. Indeed, among hunter-gatherers, peace is common 90 percent of the time, and war takes place only a small part of the time. Chimps cannot tell us anything about peaceful relations, because chimps have only different degrees of hostility between communities. Whereas bonobos do tell us something; they tell us about the possibility of having peaceful relationships.

I've argued that many of what philosophers call moral sentiments can be seen in other species. In chimpanzees, gorillas, orangutans and humans, you see examples of sympathy, empathy, reciprocity, a willingness to follow social rules. Dogs are a good example of a species that have and obey social rules; that's why we like them so much, even though they're large carnivores.