The Paranthropus boisei, a species of heavyset and bipedal hominin that roamed the Earth between 2.4 until about 1.4 million years ago, could be responsible for passing the first case of genital herpes to our ancestors.

A Global Issue

Genital herpes is considered as a global issue. As of 2012, about 417 million people globally live with the infection.

Infection with genital herpes does not often come with symptoms or merely shows mild symptoms. However, when symptoms do occur, infection is marked by genital or anal blisters or open sores also known as ulcers, as well as body aches, fever and swollen lymph nodes.

How Human Ancestors Contracted Genital Herpes

Between 3 and 1.4 million years ago, genital herpes from African apes infected our human ancestors, which researchers believe likely occurred through an intermediate hominin species unrelated to humans.

Now, researchers of a new study, which was published in Virus Evolution, found evidence suggesting that a direct Homo ancestor, the Homo habilis, may have contracted genital herpes from ancient chimpanzees by butchering and consuming meat. The Homo habilis then sexually passed the virus to Paranthropus boisei, which in turn passed it to the Homo erectus.

"Our model identifies Paranthropus boisei as the most likely intermediate host of HSV2, while Homo habilis may also have played a role in the initial transmission of HSV2 from the ancestors of chimpanzees to P.boisei," the researchers wrote in their study.

The researchers modeled how the virus was transmitted from chimpanzees to the hominins that once roamed Africa. By taking into account the changes in topography, climate data, fossil locations and geography, the researchers found Paranthropus boisei as the likely culprit indirectly responsible for giving humans the genital herpes that now infects about one in six adults in the United States.

Opportunity For Genital Herpes To Infect Ancient Human Species

The researchers explained that layering climate data and fossil locations allowed them to identify the species that most likely came into contact with the ancestral chimpanzees and other hominins at water sources.

They found that close contact between the homo erectus and P. boisei would have been common around sources of water at the time, which provided the opportunity for the genital herpes virus to jump into our species.

"For these viruses to jump species barriers they need a lucky genetic mutation combined with significant fluid exchange. In the case of early hominins, this means through consumption or intercourse — or possibly both," said study author Charlotte Houldcroft, from Cambridge's Department of Archaeology.