Herpes has been around a long time, to say the least.
Ancient chimpanzees genetically passed oral herpes (herpes simplex 1, or HSV-1) to the earliest humans millions of years ago when our lineage split. And we almost missed out on catching that other scourge, genital herpes (HSV-2) -- almost. Unlike HSV-1, HSV-2 didn't make the leap to early humans on its own.
Unfortunately for modern humans, millions of years ago, an early human ancestor was in the right place at the right time to catch HSV-2. And it might not have happened if it weren't for that meddling hominin species Paranthropus boisei, according to a new study in the journal Virus Evolution.Why Paranthropus boisei, you ask? After all, P. boisei was not even on the main line of human evolution, coexisting with all manner of early Homo species at the same time, who likely out-competed them into extinction. From the article, which is highly technical:
Paranthropus boisei would have been well placed to act as an intermediate host for HSV2. It most likely contracted the infection through hunting or more likely scavenging infected ancestral-chimpanzee meat. Processing (with or without tools) and consumption of raw meat would act as a simple path for ChHV1 to have crossed into P.boisei via open cuts or sores. Tropical refugia during hot dry periods may have driven chimpanzees into higher concentrations in certain areas, driving them into contact and competition with P.boisei and H.habilis as the margins of tropical forest blended into more open savannah-like habitats (Julier et al. 2017). Violent confrontation or hunting/scavenging and butchery practices would have provided a viable path of transmission for HSV2. Homo habilis remains have been recovered from the same layers as stone tools and bones carrying evidence of butchery, supporting a possible transmission–through-hunting/scavenging hypothesis for the initial anc-chimp to H.habilis transmission (Clarke 2012). Paranthropus aethiopicus, P. boisei, and P. robustus are associated with the Oldowan stone tool complex (De Heinzelin et al. 1999), and P.boisei explicitly with butchery (Domínguez-Rodrigo et al. 2013) lending support to the hypothesis that bushmeat hunting/scavenging and butchery may have led to the initial transmission of HSV2 to the hominins.The entire exercise is very mathematical and relies on somewhat limited evidence of P. boisei behavior. It is, nonetheless, intriguing since it posits considerable interaction between the various hominin groups.
Here is a mugshot of one of the perpetrators, the Zinj skull from Olduvai Gorge, found in 1959.