Scientists believe they may have identified the species of hominin from which human ancestors became infected with genital herpes (HSV2) between 3 and 1.4 million years ago.

Researchers from Cambridge and Oxford Brookes universities believe that Paranthropus boisei allowed the HSV2 virus to jump the species barrier from African apes into human ancestors. It was a heavyset bipedal hominin with a smallish brain and dish-like face. The researchers suggest that P. boisei most likely contracted HSV2 through scavenging ancestral chimp meat where savannah met forest – the infection seeping in via bites or open sores. The appearance of Homo erectus around 2 million years ago was accompanied by evidence of hunting and butchery. Consuming “infected material” would have transmitted the virus. The scientists believe that such interaction between both species might have occurred around sources of water, such as Kenya’s Lake Turkana. They state that a lucky genetic mutation combined with significant fluid exchange might have could have taken place allowing for these viruses to jump species barriers. The researchers Krishna Kumar, Simon Underdown and Charlotte Houldcroft used Bayesian network modelling on data collected from fossil finds,  herpes DNA and ancient African climates. The team generated HSV2 transmission probabilities for the mosaic of hominin species that roamed Africa. It was discovered that Paranthropus boisei fit as the herpes intermediary in all the scenarios with high probabilities.

(after Popular Archaeology, Louise Walsh, Simon Underdown and Charlotte Houldcroft)