Lice hint at a recent origin of clothing.

It began when Mark Stoneking's son brought home a note saying a kid at school had lice. While another parent might react with disgust, the anthropologist was intrigued by these microscopic creatures.

Stoneking turned his new fascination with lice into a research project, one that offers a solution to the longstanding mystery of clothing was invented. After discovering that head lice live and feed on people's scalps while so-called body lice feed on skin but live only in clothing, Stoneking and his colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, looked into the origins of the two species. "That distinction probably arose when humans began to make frequent use of clothing," Stoneking argues.

By comparing the DNA of human lice from around the world, the researchers estimate in the Aug. 19 Current Biology that body lice diverged from head lice about 72,000 years ago, give or take 42,000 years.

"Even looking at the extremes of that range, it still associates the origin of body lice, and thus by inference the origin of clothing, with modern humans," says Stoneking. "People, without thinking about it, just assume that clothing is probably much older."

Since clothing doesn't fossilize, there's little direct data bearing on its invention. Anthropologists have dated possible sewing needles to about 40,000 years ago, and Olga Softer of the University of Illinois in Urbana-Champaign has argued that figurines and pottery from about 27,000 years ago show evidence of woven clothing (SN: 10/21/00, p. 261).

For their study, Stoneking and his colleagues sequenced four stretches of DNA in 40 samples of human or chimpanzee head or body lice. Using the differences in the genetic sequences and estimates of how quickly DNA mutates, the researchers deduced when the common ancestors of various lice lived. The data also indicated that body lice arose from head lice, as Stoneking expected.

Other researchers praise the creativity of the lice study but express skepticism about its conclusions. Softer, who worked in the fashion industry before becoming an anthropologist, notes that a dispute remains whether head and body lice are distinct species. The new report is "a nice attempt but leaves much to be desired on many fronts," she says.

Ian Tattersall, a paleoanthropologist at the American Museum of Natural History in New York, notes that more than 500,000 years ago, hominid species such as Neandertals lived in northern European locations that would have been very cold at times. Neandertals would have been hard-pressed to survive without wearing animal hides or some other sort of clothing, he says.

Tattersall adds that Stone king's conclusion rests upon the assumption that body lice arose almost immediately after clothing emerged. "I fear [this study] may show that the origin of clothing was not exactly the same as the origin of body lice," says Tattersall.

Before focusing on clothing, Stoneking wondered whether lice could shed light on where modern humans originated. His team found that African samples of human lice are more genetically diverse than are lice from other regions, implying that human lice, and therefore humans, arose there. "It seems to mesh very well with the idea modern humans first spread out of Africa 50,000 to 100,000 years ago," says Stoneking.