The human louse finds people so delicious that it will accept no substitutes and cannot live more than a few hours away from the warmth and sustenance of the human body. This devotion to the human cause means that the evolutionary history of human lice dovetails with that of their hosts and reflects several pivotal events that affected both species.
In a finding that seems bound to inspire several science fiction treatments, Dr. David Reed of the Florida Museum of Natural History in Gainesville has reached the startling conclusion that some human lice show signs of having evolved originally on a different human species.
In today’s issue of the journal PLoS Biology, he and his colleagues suggest that modern humans may have contracted this strain of lice from an archaic human like Homo erectus.”
More here by Nicholas Wade in the New York Times.