The latest story doing the rounds of the scientific press and blogs is that of the date at which humans and chimpanzees diverged from a common ancestor. A study of genetic sequences and the fossil record implies that a split could have occurred around 7.4 million years ago, with interbreeding and possible full hybridisation until 6.3 million years ago.

Although this report conjures up highly disturbing images of human-chimp marital relations, when the (initial) split ocurred the two species would most likely have been similar in appearance and behaviour. A modern analogy might be that of interbreeding between different species of dog, which few people are up in arms about.

Nature: Chimpanzee and human ancestors may have interbred
New Scientist: Did humans and chimps once interbreed?