By Luke Andrews
Scientists have uncovered a genetic link between our pubic lice (Pthirus pubis) and those of Gorilla’s (Pthirus Gorillae). A study published in BMC Biology used phylogenetic analysis to show that our pubic lice originate from Gorilla’s.
Two different species of hair-loving lice live on humans. One lives on our head, the other in our pubic region. The parasite is near-microscopic in size and feeds by sucking blood from its host. Their body is poorly designed for movement.
“[Lice] can’t fly, they can’t jump, and they can’t live apart from on their host for any period of time”, said Mark Pagel, Professor of Evolutionary Biology at University of Reading in an interview with National Geographic.
Morphological studies of the lice genera Pthirus indicated a close relationship between the human and Gorilla variant. The two species look very similar. When their DNA was analysed, it revealed that the two species separated 3 – 4 million years ago. This is later than the split between Gorilla’s and the Homo lineage which happened 7 million years ago, suggesting that pubic lice jumped between species.
It was theorised that sexual contact occurred between the Homo lineage and Gorilla’s.
“It is quite possible that the lice were transmitted sexually” said the study leader Dr David Reed from the University of Florida in Gainesville to National Geographic.
Luckily, it can’t be Homo sapiens that are responsible for the lice swap. We hadn’t evolved by 3 – 4 million years ago, so the lice must have moved from Gorilla’s onto an early human ancestor like Australopithecus.
Although early human SEX with Gorilla’s cannot be ruled out, Dr Reed believes it is more likely that we acquired Gorilla’s pubic lice by living in close proximity to them. He thinks that using the same sleeping sites as Gorilla’s, or scavenging Gorilla remains are more likely explanations for how we received pubic lice.
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