Raugust

Yeah, that's why I'm asking about gorillas. Since we're having difficulty deciding whether the common ancestor of humans and chimpanzees was (behaviorally) more like a bonobo or more like a common chimpanzee, I'm curious about whether gorillas are behaviorally more like a bonobo or more like a common chimpanzee, as a more indirect way of gaining some evidence regarding our common ancestor -- from knowledge about the previous common ancestor.

I hear a lot of disputes over whether humans have more in common with bonobos or with common chimpanzees, the two species who are (equally) our closest relatives. Genetically, the question may be meaningless, since chimpanzees split off from us before splitting from each other. But it remains possible that our behavioral similarity to one of these species is based more on convergence, while our similarity with the other species is based more on common descent. Here's a line of questioning that may shed light on the former question, and that I haven't heard explained elsewhere: How similar are our other closest great ape relatives (chiefly gorillas, but also orangutans) to each of the chimpanzee species? Is one or the other especially unusual, in the context of the hominids or hominoids? And is there a good resource where I could see comparative ethological work along these lines?