On head lice and social interaction in archaic Andean coastal populations.

Archaic mummies from northern Chile were examined for the presence of Pediculus humanus capitis. The excellent preservation of mummies and louse nits/eggs permitted a study of the degree of head lice infestation. We studied 63 Chinchorro mummies (ca. 5000-3000 years B.P.) from the Arica-Camarones coast. An area of 2cm×2cm on each mummy's head was systematically inspected for louse nits/eggs. Hairs with nits/eggs and lice were collected and analyzed using optic and scanning electronic microscopy. About 79% (50/63) of the mummies resulted positive for pediculosis, with an average of 2.1nits/eggs/cm2 per positive individual. Microscopic analyses revealed the micromorphology of all developmental stages, including eggs/nits, nymphal instars and adults. Chinchorro people lived in small huts increasing the transmission of ectoparasites. Considering that head lice thrive in crowded conditions, their prevalence could be used as an bioindicator to assess and debate cultural behavior (e.g., degree of crowdedness and sedentism) and to study paleoepidemiology in prehistoric populations.