Gorilla Sex?

Gorillas may have been responsible for the introduction of pubic lice in humans, according to a new study. Evolutionary biologist David Reed of the Florida Museum of Natural History in Gainesville USA has traced the genetic structure of lice and worked out when they first appeared, and the results show the lice, which infect some three million Americans a year, evolved well before they first plagued humans.

This suggests humans must have had close contact with gorillas to first become infected, posing the question: just how did they jump from gorilla to human, and what were the humans and gorillas doing at the time?