Molecular Evolution of Pediculus humanus and the Origin of Clothing

Abstract

In volume 13, issue 16 of Current Biology (pp. 1414–1417), we used a molecular-clock approach to date the origin of human body lice and, by inference, the origin of human clothing. To calibrate the molecular clock, we obtained mtDNA and nuclear gene sequences from a chimpanzee louse (Pediculus schaeffi). Reed et al. (PLoS Biol 2:e340, 2004) recently reported that the mtDNA cytochrome b (CYTB) sequence we reported for the chimpanzee louse fell outside the range of other Pediculus CYTB sequences [1Reed, D.L., Smith, V.S., Hammond, S.L., Rogers, A.R., and Clayton, D.H. (2004). Genetic analysis of lice supports direct contact between modern and archaic humans. PloS Biol 2(11): e340.Google Scholar]. After further investigation, we determined that our P. schaeffi CYTB sequence is closely related to Chironomus CYTB sequences and, hence, most likely reflects a contaminant. The sequences we reported for the mtDNA ND4 gene and the nuclear genes RPII and EF-1α from this chimpanzee louse do appear to reflect authentic P. schaeffi sequences. Reanalysis of our data with the P. schaeffi CYTB sequence from Reed et al. along with the rest of our CYTB and ND4 sequence data results in a time of 770,000 years for the human louse ancestor and 107,000 years for the origin of body lice. No other analyses are influenced by the incorrect P. schaeffi CYTB sequence, and none of our conclusions are changed.