A report of the study appears in the Proceedings of the Royal Society B.
The team chose its study subjects because humans, chimps and their lice share a common historical fate: When the ancestors of humans and chimps went their separate ways, evolutionarily speaking, so did their lice.
“Humans are chimps’ closest relatives and chimps are humans’ closest relatives – and their lice are each others’ closest relatives,” said study leader Kevin Johnson, an ornithologist with the Illinois Natural History Survey at the University of Illinois. “Once the hosts were no longer in contact with each other, the parasites were not in contact with each other because they spend their entire life cycle on their hosts.”
This fact, a mutual divergence that began at the same point in time (roughly 5 million to 6 million years ago) allowed Johnson and his colleagues to determine whether molecular evolution occurs faster in primates or in their parasites.
Read more at: Phys.org