The earliest evidence for lice infesting humans is a 10,000-year-old specimen of a Brazilian mummy's lice-ridden hair. Evidence was lacking, however, that prehistoric South Americans created and used combs to remove the pests. Now the first such objects thought to be made and used for this practice have been found by scientists in Chile, Brazil and the U.S.

The combs are made of barbed reeds with thin, tightly-spaced teeth. All were found at five sites in northern Chile and are estimated to be between 240 and 800 years old. Under a microscope, lice, nits (eggs) and hatched nits can be seen in the combs. “Given the nature of the combs—the teeth close together—it seems they were designed for personal delousing,” says Bernardo Arriaza of the University of Tarapaca’s Institute of Higher Learning in Arica, Chile, lead author of a new paper reporting the finding. The lice and eggs trapped in the structures also support this interpretation.

The combs were discovered at a site known as Cultura Arica, a pre-Columbian agricultural town in the north of Chile dated to A.D. 1000 to 1500. Researchers, however, suspect the area might have extended further across the continent and to more remote locations.

Kosta Mumcuoglu, a physician and parasitologist at The Hebrew University of Jerusalem Hadassah Medical School, agrees that the newly studied objects likely are combs used to remove lice. In 1989 he and a colleague reported finding lice combs, dated to 1500 B.C. in caves in Israel. “I am sure that there could be more combs, older combs, in America,” Mumcuoglu says, “but we have to find and examine them.”

Almost all the combs studied have two faces and were made with 21 to 69 barbed reeds (Phragmites australis) fastened to two shafts. Cotton thread ties together the entire structure in a decorative pattern. The average separation between the teeth was a half-centimeter, resulting in “less efficient but adequate combs to remove nits and the back section of lice,” the researchers wrote. The results were detailed in Chungara, Revista de Antropología Chilena (The Journal of Chilean Anthropology).

Lice have been linked to human beings dating back to our prehominid ancestors. One of the oldest known medical documents, the Ebers papyrus, includes a treatment for lice using powder made from dried dates. The combs at Cultura Arica are thought to have been developed in response to a stressful, endemic outbreak.

Were other complementary treatments used to treat lice in this population? “I suppose herbs,” Arriaza says. “But given the quantity and density [of lice these people had], I don’t think these methods would be very effective.”