Current human louse genetic diversity as a proxy to detect ancestral hominins direct contacts

M ASCUNCE; DAVID L. REED; TOLOZA A; ANGELICA GONZALEZ-OLIVER

Conferencia; International Conference on Phthiraptera 6; 2018

Evolutionaryhistories of parasite and host populations are intimately linked such that the use of parasites may revealaspects of host evolution that are not preserved in the archeological record orare poorly resolved in host DNA. Pediculus humanus is an obligateblood-sucking ectoparasite of humans and is so closely tied to its host in bothecological and evolutionary time, that they have the potential to shed light onnot only the host's evolutionary past, but also on host ecology. One emergingquestion in human evolution is the nature of contact and introgression between anatomicallymodern humans (AMHs) and ancestral hominins in regions where they co-occurred. An assessment of the geneticvariation at microsatellite markers in 274 human lice from 25 geographic sitesworldwide revealed the presence of two distinct genetic clusters (Cluster I andCluster II) that diverged about 800,000 years ago paralleling the divergence betweenAMHs and Neanderthals. In other recent studies, multiple mitochondrialhaplogroups of lice have been found as well. In our samples, we detected twodifferent mitochondrial haplogroups: A and B, however recent studies havedetected a total of five haplogroups, thus our results reflect only a partialpicture of the human louse genetic diversity. We hypothesize that the twodistinct genetic clusters based on nuclear data (Cluster I and Cluster II)could be the result of coevolution between AMHs and archaic hominins likeNeanderthals. If true, louse current genetic diversity suggests a high level ofdirect contact between these ancestral host populations.