John Hawks shared an interesting news bit the other day. The study basically sampled head lice off of 1,000 year old Peruvian mummies and with some sequence variation comparisons to other lice, the authors were able conclude that lice have been with humans ever since they migrated out of Africa. I’ve tracked down the original paper to investigate their claim.
The paper, “Molecular Identification of Lice from Pre‐Columbian Mummies” is published in an early release of the Journal of Infectious Diseases. The authors amplified the Cytb and Cox1 genes of lice found on three 1,000 year old Peruvian mummies. The mummies are associated with the Chiribaya culture, a post Moche movement, that originated in the Azapa Valley of Northern Chile. I’ve cut and pasted a photo of one of the mummies sampled from the article, in this photo the authors show the lice still present on the head.
They next sequenced these amplified genes, and constructed phylogenetic trees of the genetic similarities these lice have to sequences of lice from other areas of the world. What they found from their cladistic analysis was that the lice associated with the mummies clustered only with sequences in the type A clade. Since type A clade are almost exclusive to Asia and Africa, the authors could confidently claim that the lice were not of European origin, which sports the type B clade of lice.
New World mummies as old has 10,000 years ago have lice, and the genetic evidence from this study now confirms the lice that existed in New World for the last 1,000 years was not of European origin. This work also tells of migration patterns of humans, much like the study on rat genetics did early this week. We can see that founding populations of people from the Old World carried over the type A clade of lice, over the Bering straight and to the Americas.
I really appreciated this article. Had it not been for this one citation to the Bible, about the presence of lice in historical populations, I would say this article is a perfect example of simple, enlightening science. The authors didn’t obfuscate their research and provided a very graceful example of how a host-speciﬁc parasites of human brought in an additional line of evidence to understand human migrations. One last thing, I wonder what’s the genotype of the lice found on the mummies in Arizona?
Raoult, D., Reed, D., Dittmar, K., Kirchman, J., Rolain, J., Guillen, S., Light, J. (2008). Molecular Identification of Lice from Pre-Columbian Mummies. The Journal of Infectious Diseases DOI: 10.1086/526520