Hangers-On: Body Lice and the Origin of Clothes
Humans are often described as the ‘hairless ape’. It is a feature which separates us starkly from almost all other mammals, and is a trait thought to have arisen 1.2 million years ago. Exactly why humans lost their hair is still a subject of heated debate amongst archaeologists but one consequence of this loss was that our ancestors needed to find novel ways to keep warm as they ventured north from their tropical homelands. In Europe, parts of Asia and North America it would have been impossible to survive the climate without clothing. Exactly when clothing was first used however, is even more contentious then the reasons for our hair loss. The oldest needle discovered is only 40,000 years old, by which time humanity had colonised several continents and was pushing into Europe. So is there another way of looking at this problem?
Direct evidence of clothing is hard to find, so instead attention has turned to the humble body louse. These tiny parasites are scientifically known as Pediculus humanus corporis and unlike all other lice species known to exist, they don’t live on hair. Humans do have two species which still inhabit our hair, but body lice are totally adapted to living in the seams of our clothes. By measuring the genetic differences between them and their closest relatives, our head lice, scientists at the Max Planck Institute for Evolutionary Anthropology were able to calculate how long ago these two species diverged. They took DNA samples from 40 body and head lice to compare and constructed a family tree for our body lice. They calibrated their tree’s dates against the known split between human and chimpanzee head lice and then applied it to body lice. The result was startling. Body lice separated from head lice between 83,000-170,000 years ago. This makes them exclusively human parasites, excluding even our closest relatives the Neanderthals. This makes clothing an equally human invention and shows that 100,000 years ago our ancestors were already equipped with one of the essential technologies which would allow them to colonise every corner of the world.
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