Human Head and Body Lice in History
A Collection of Facts About the Louse and its Impact on People
Apr 5, 2009
We think of lice as repulsive parasites that need to be killed, but lice and humans share a long history of both good and bad.
Where Did Lice Come From?
Scientists believe that the ancestors of human lice evolved on Earth long before the appearance of modern humans—Homo sapiens. As long as we’ve been here, we’ve had lice, and for most of that time, they did us little harm.
Lice in Early Medicine
Most accounts of lice in early medicine focus on the question of how they infested people and, surprisingly, what the benefits of louse infestation were. In both Chinese and Western medicine, people thought that lice appeared spontaneously, perhaps from perspiration, dirt, or moisture. The philosopher Aristotle believed that lice emerged from the skin (Hoeppli, 346).
A healthy population of head lice was widely believed to protect against disease, especially in children, and to be a sign of general good health. In addition, both Chinese and Western doctors used the tiny insects to treat health problems such as eye inflammation, toothache, jaundice, urinary troubles, and epilepsy. Lice, some people believed, could predict the sex of an unborn baby.
Because lice have the disturbing habit of abandoning a person who is feverish, near death, or deceased, many have thought lice can predict the outcome of an illness: if a louse placed near the patient walks away, the patient is sure to die.
Cultural Meanings for Lice
Every human culture on Earth has lice—it's not surprising that people have found uses for them:
- Young Siberian women reportedly threw lice at attractive men as an offer of marriage (Zinsser, 136).
- In the Middle Ages in Hurdenberg, Sweden, candidates rested their bearded chins on a table and a louse placed on the table chose the mayor for the next year (Zinsser, 137).
- In many cultures, shaving the head and wearing a wig may have been an attempt to avoid head lice.
- Various cultures have eaten lice, which has the additional benefit of ensuring that the parasites are permanently removed.
The Harm in Head and Body Lice
Unless they become particularly numerous, lice cause few health problems. The main danger of lice lies in their ability to transmit disease: it's the body louse, not the head louse, that's infamous. Body lice transmit three bacterial diseases:
- Epidemic typhus (high mortality rate).
- Relapsing fever (relatively low mortality rate).
- Trench fever (serious but usually not fatal).
All of these diseases appear where people have heavy infestations of body lice: in famine, war, poverty, homelessness, overcrowding etc. Typhus, in particular, has ravaged armies and changed the outcome of wars.
Lessons from Lice Today
Today scientists use lice to learn more about people. Molecular studies suggest that:
- About 100,000 years ago, one species of louse crossed over to Homo sapiens from an archaic species of Homo—obviously during close contact.
- Body lice evolved between 42,000 and 72,000 years ago, pinpointing the time when humans began to regularly wear clothing.
- A person’s DNA in a louse’s belly can be identified, a discovery with implications for forensic investigations.
Perhaps lice aren’t all bad.
Sources:
“Genetic Analysis of Lice Supports Direct Contact Between Modern and Archaic Humans.”
Reed, David L., Vincent S. Smith, Shaless L. Hammond et al. PLoS Biology 2: 11, 2004. e340
“Molecular Evolution of Pediculus humanus and the Origin of Clothing.” Kittler, Ralf, Manfred Kayser, and Mark Stoneking. Current Biology 13: August 19, 2003. Pg. 1414–1417.
Parasites and Parasitic Infections in Early Medicine and Science. Hoeppli, R. Singapore: University of Malaya Press, 1959.
Rats, Lice and History. Zinsser, Hans. New York: Bantam, 1965.
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