Where Does Herpes Come From? Scientists Think They’ve Found The First Instance Of Genital Herpes
If you've ever been diagnosed with herpes simplex virus 2, the type of herpes that almost exclusively shows up on the genitalia, you might think to blame the partner who gave it to you, but they have to have gotten it from somewhere, too. Scientists think they've found the earliest instance of the virus in an animal, shedding light on how it has evolved to the infection we know today. It turns out that, unlike herpes simplex I, HSV2, as it's called, was probably transmitted into humans by a creature unrelated to our ancestors: Paranthropus boisei, a flat-faced, thick-toothed hominid alive millions of years ago. How the virus made the jump from an unrelated animal to early humans and now to us, though, is a pretty wild story.
Figuring out where diseases came from in humanity's distant past is often a fascinating puzzle, with big implications for how the modern-day version of the illness might be treated or understood. The most well-known of these centers around HIV, which appears to have shown up in some form in primates, like lemurs, for millions of years. But medical historians are also interested in the evolution of diseases like cancer, and whether they've been influenced by shifts in human lifestyle over the centuries, or have just been part of our biological experience for millennia. When it comes to herpes, humanity appears to have been aware of it since at least ancient Greece; the physician Hippocrates described herpes-like lesions, and the modern word "herpes" comes from the Greek for "creep or crawl," to describe the spread of blisters. But new science out of Cambridge may reveal that the virus goes back much, much further than that.
An Ancient Hominid Is Responsible For Bringing Herpes To Humans
We've known for a few years that the two varieties of herpes have had different journeys in human history, because herpes genes have been sequenced. One, HSV-1, has been around in human biology since before we split off from other primates. The other faded away, but was reintroduced back, and now Cambridge scientists have a theory about how that happened, and what distant relative was responsible.
In new research published in Virus Evolution, the scientists used geographic analysis and probability models to identify which hominid ancestors were most likely to come into close proximity with humans between 1.4 and 3 million years ago, which is the time period when herpes simplex 2 "jumped the species barrier," as it's called, or came from apes back into human ancestors.
The culprit, P. boisei, was simply "in the right place at the right time," the researchers say. (Or wrong place, depending on your feelings about HSV2.) They looked at fossils, chimpanzee and bonobo populations, and where ancient rainforests would have flourished, to see where P. boisei may have roamed. It turns out it's the most likely species to have come into contact with Homo erectus, as humanity's most direct ancestor is called, and given it HSV2.
The Cambridge scientists think that P. boisei likely ate some chimpanzee or bonobo meat that had the virus, got infected, and later spread it to Homo erectus, either by having sex with them, fighting them, or becoming their dinner. (Yes, hominids including Homo erectus ate each other; modern chimpanzees are such effective hunters they risk wiping out entire monkey populations.) This sort of thing is called "cross-species transmission," and explains how diseases can pass between different animals, particularly something like HSV2, which, as you may remember from sex ed, is transmitted through fluids and mucosal surfaces.
P. boisei has no relation to us humans, so it's not like various members of the family tree were chowing down on one another, but it's still a pretty macabre thought.
What This Means For Herpes Now
Herpes simplex 2, which is carried by around 17 percent of American adults, is mostly just uncomfortable, but it can be a particular issue for pregnant women, who are more likely to miscarry if they contract it and may pass it to the fetus. It's also been linked to encephalitis. Stigma against people who have herpes is also a major issue that can affect self-esteem and the ability to maintain healthy relationships, which is a health issue of itself.
Studies of the genetics of herpes that lead to discoveries like this are also leading to more modern discoveries. In 2016, a study revealed that gene-editing technology could help suppress or eliminate the virus, which is currently controlled by antiretroviral medications. More research is needed, so you won't find a handy gene-edit kit at your drugstore in time for your next breakout, but it's definitely providing hope for the future. In the meantime, HPV-2 is definitely treatable, but now you know what ancient animal to shake your fist at.