In a creative use of insect genetics to solve an enduring mystery of human evolution, scientists studying the DNA of lice have concluded that early humans may have started wearing clothes just a few tens of thousands of years ago, more recently than many had presumed.
The new work—based on subtle genetic differences between human body lice, which depend on clothing for their survival, and human head lice, which do not—suggests that early humans may have lived in Europe for tens of thousands of years after leaving Africa before availing themselves of clothes.
Among the work's controversial implications: Early humans such as Neanderthals—who lived from about 150,000 years ago until 30,000 years ago and who are typically depicted as hairless and clad in furs—may in fact have been quite furry until surprisingly late in their evolution.
If you look at how Neanderthals are routinely depicted in books and
museums, people have just thought they must have had clothing to
protect against cold weather, said study leader Mark Stoneking of
the Max Planck Institute for Evolutionary Anthropology in Leipzig,
But if you ask, ‘What's the evidence?’
it's just not compelling that they had clothes. Perhaps they had
more body hair than we thought.
The transition from hairy to hairless, and the related advance from naked to clothed, were seminal events in human biological and cultural evolution. But scientists know little about the timing of either.
Fur and fabrics typically rot before they fossilize, so there are no lasting remnants of these coverings more than a few thousand years old. Ancient needles and other artifacts indicate that people were weaving and sewing at least 25,000 years ago—and perhaps as many as 15,000 years before that. But some researchers believe that the human trek from naked wilderness to the runways of Paris and Milan began well more than 100,000 years ago.
Anthropologists are especially interested in knowing when people graduated from crude animal-skin togas to sewn, tailored and decorated clothing—a major cultural advance that offered new ways to broadcast information about tribe, social status or fertility.
In terms of warmth, you can wrap yourself in a hide, for God's
sake, said Olga Soffer, an archaeologist at the University of
But clothes let you really make much more complex
statements. The body is turned into a stage to play all of the kinds
of social games you can invent.
Scientists studying early human culture are increasingly turning to genetic techniques—either studies of ancient human DNA or the DNA of plants and animals that coexisted with early humans—to get around the lack of traditional archaeological evidence. But there is little consensus on how to interpret the first rounds of results.
So while several scientists agreed that the new louse study was
wonderful and, in the
words of one prominent geneticist,
way cool—all cautioned
against reading too much into the findings.
Indeed, some noted, University of Utah researcher Alan Rogers is about to publish new human DNA research suggesting that human forbears lost their hair more than a million years ago—earlier than has been presumed. But those findings, too, are in dispute, an indication of the confusion that surrounds such studies today.
The new work, published in today's issue of the journal Current Biology, focused on parasitic lice—highly successful insects that do not merely hatch but literally blast out of their eggs after pumping them overly full of air—and then live out their bloodthirsty lives biting, chewing or piercing their hosts.
Individual species of lice are intensely specialized, largely to avoid grooming and preening behaviors by creatures trying to get rid of them. Some bird lice, for example, live only on the heads of their feathered hosts, where nitpicking beaks cannot reach. Others live only inside animal quills or in other specialized spots.
Stoneking took advantage of a specialization that separates two species of human lice. Head lice stay on the head and glue their eggs to the shafts of hairs (with a cement that dries so hard and so fast that the female sometimes gets fatally stuck there by mistake). Body lice, by contrast, feed on hairless parts of the body and lay their eggs only in clothing, especially in protected areas such as seams.
By figuring out when body lice first appeared, the team reckoned it
would get a good idea of when clothing arose.
that clothing may have existed for some time before body lice,
But in general . . . when a new ecological niche
becomes available, organisms move in very quickly.
The researchers first compared the genetic codes of human and chimpanzee lice, to get a measure of how rapidly louse genes mutate. They found 170 mutations separating the two kinds of lice. With chimpanzees and humans taking separate evolutionary paths a little more than 5 million years ago, that came out to about one mutation every 30,000 years.
Then they compared the DNA from 40 human head lice and body lice that scientists had sent from around the world. Using the molecular metronome of one mutation every 30,000 years, they determined that human body lice branched off from a preexisting line of head lice about 72,000 years ago—suggesting an origin of clothes around that time.
The estimate is rough. Because of the relatively small number of louse samples used and other complications, the team concedes, clothing may have arisen as recently as 30,000 years ago or as long as 114,000 years ago—a big window that leans toward the recent but encompasses other leading theories based on actual artifacts.
Kevin Johnson, an evolutionary biologist with the Illinois Natural
History Survey, was one of several experts who said he admired
Stoneking's approach but was uncertain about its statistical
validity. He said his best reading of the data is that clothing
appeared sometime between
170,000 years ago and yesterday.
David Reed, a molecular evolutionary biologist at the University of Utah, said some scientists believe that head and body lice stopped interbreeding and became genetically distinct only recently. If true, that would confound the new findings even more.
And Stoneking himself said he was not sure if the first body lice had to wait for real tailoring with sewn seams, or whether their arrival is a mere indicator of simpler, partly form-fitting furs. He hopes that follow-up studies on pubic lice genes will help clarify the kinds of clothes early humans wore.
It's always going to be hard to talk about when clothing
started because it depends on what you mean by clothes, said Anne
Hollander, a historian of art and clothing and author of
But the real purpose of clothing is universal, she said.
always a combination of sex and politics.