Research into the genetics of modern head lice suggests that modern humans lived alongside our ancient relatives Homo erectus .
DNA research on the human head louse, Pediculus humanus, has been carried out at the University of Utah and published in the PLoS Biology (Public Library of Science Biology) open access journal.
The studies have discovered two genetically distinct lineages of modern head lice that diverged about 1.18 million years ago, around the time that our ancestors may have begun to differentiate from the species Homo erectus .
But the fact that both types of head lice are now found on modern humans suggests that Homo erectus and modern humans must have had contact to enable the other form of parasite to 'jump' between the human species.
The genetic study of head lice can be closely tied in with the genetic study of human evolution as the parasite is likely to evolve in tandem with its host. The genetic analysis indicates that Homo erectus and modern human must have had close contact, possibly living side by side or by fighting or even cannibalism, around 25,000 years ago.
Professor Chris Stringer, human origins expert at the Natural History Museum, said ‘Some degree of human contact would have been necessary to reunite the two lineages of head lice found in recent humans, although the contact was not necessarily extensive or prolonged.’