David Reed, associate curator of mammals at the Florida Museum of Natural History on the University of Florida campus, worked with colleagues worldwide for five years to sequence the DNA of clothing lice to determine when they first began to diverge from the harmless but cringe-inducing head louse.
The study, in this month’s print edition of Molecular Biology and Evolution, finds that the one louse species began to diverge into two about 170,000 years ago, 70,000 years before humans started migrating to colder climates, which began about 100,000 years ago.
Because clothing doesn’t last for 170,000 years, looking at lice was the best way to deduce this.
Interestingly, humans seem to have started wearing clothes well after they lost body hair, which genetic skin-coloration research puts at about 1 million years ago. That means that people spent a good long while wandering around without protective and warming body hair and without clothing, says Reed.
“It wasn’t until they had clothing that modern humans were then moving out of Africa into other parts of the world,” Reed said.
A previous study of clothing lice in 2003 by geneticists at the Max Planck Institute in Leipzig, Germany, estimated humans first began wearing clothes about 107,000 years ago. But the Florida researchers think their data and calculation methods are more precise.