U. FLORIDA (US) — Humans started wearing clothing and migrating out of Africa about 170,000 years ago. How do scientists know? Lice.
Perhaps surprisingly, the wearing of clothes began well after the loss of body hair, which genetic skin-coloration research pinpoints at about 1 million years ago, meaning humans spent a considerable amount of time without body hair or clothing.
“It’s interesting to think humans were able to survive in Africa for hundreds of thousands of years without clothing and without body hair,” says David Reed, associate curator of mammals at the Florida Museum of Natural History at the University of Florida.
“It wasn’t until they had clothing that modern humans were then moving out of Africa into other parts of the world,”
Reed, who used DNA sequencing to calculate when clothing lice first began to diverge genetically from human head lice, says lice are good candidates for study because unlike most other parasites, they are stranded on lineages of hosts over long periods of evolutionary time.
The relationship allows scientists to learn about evolutionary changes in the host based on changes in the parasite.
“We wanted to find another method for pinpointing when humans might have first started wearing clothing. Because they are so well adapted to clothing, we know that body lice or clothing lice almost certainly didn’t exist until clothing came about in humans.”
The research is reported in the journal Molecular Biology and Evolution.
Applying unique data sets from lice to human evolution has only developed within the last 20 years, and provides information that could be used in medicine, evolutionary biology, ecology, or any number of fields, Reed says.
“It gives the opportunity to study host-switching and invading new hosts—behaviors seen in emerging infectious diseases that affect humans.”
A study of clothing lice in 2003 led by Mark Stoneking, a geneticist at the Max Planck Institute in Leipzig, Germany, estimated humans first began wearing clothes about 107,000 years ago. But the current research includes new data and calculation methods better suited for the question.
“The new result from this lice study is an unexpectedly early date for clothing, much older than the earliest solid archaeological evidence, but it makes sense,” says Ian Gilligan, lecturer in the School of Archaeology and Anthropology at The Australian National University.
“It means modern humans probably started wearing clothes on a regular basis to keep warm when they were first exposed to Ice Age conditions.”
The last Ice Age occurred about 120,000 years ago, but the study’s date suggests humans started wearing clothes in the preceding Ice Age 180,000 years ago, according to temperature estimates from ice core studies, Gilligan says.
Modern humans first appeared about 200,000 years ago.
Because archaic hominins did not leave descendants of clothing lice for sampling, the study does not explore the possibility archaic hominins outside of Africa were clothed in some fashion 800,000 years ago.
But while archaic humans were able to survive for many generations outside Africa, only modern humans persisted there until the present.
“The things that may have made us much more successful in that endeavor hundreds of thousands of years later were technologies like the controlled use of fire, the ability to use clothing, new hunting strategies, and new stone tools,” Reed says.
Researchers from Indiana University, Penn State, and Texas A&M University contributed to the study, which was funded by the National Science Foundation.
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