Crabs and Human Evolution

You'd be amazed by what parasites can tells us about our evolution. A group of scientists that had previously published findings on human head lice, just published recent research that looked at the co-evolution of human pubic lice (crabs) with humans. The findings are interesting, raise more questions than they answer -- but provide a different lens through which human evolution can be studied. Pubic lice (Pthirus pubis) has at least a thirteen million year history with us -- going on the evolutionary journey with the distant ancestors of today's great apes and the ancestors of humans and chimpanzees. Somewhere on the journey however, Pthirus pubis became extinct on the human/chimp lineage. Then about three and half million years ago, Pthirus pubis from the gorilla lineage, reappeared on our hominid ancestors. What happened?

Pthirus pubis is only shared via close contact, which implies that our hominid ancestors shared more with the ancestors of gorillas than had previously thought. Today's gorillas are confined to forests, while early hominids were thought to have taken to the open savannah. Was that the case in the past however? Were there savannah based gorillas or forest dwelling hominids? Carl Zimmer has more on the story and speculation on his site.