Tracing Human History … with Herpes

A traveling virus affirms the theory that humans came out of Africa.

cold soreNobody loves herpes simplex virus type 1, the bug that causes those wretched cold sores. And yet it runs in families, since it tends to be spread by common signs of affection, like kisses and hugs. So maybe it’s fitting that researchers have now used HSV-1 to trace the path of the human family around the globe.

A team at the University of Wisconsin-Madison collected strains of HSV1 from America, Europe, Africa and Asia, teased them apart to decipher their genetic codes, and then compared the strains to one another. Their findings? The African strains all grouped together genetically, as did the European ones, the Asian ones, and all but one strain from America. “What we found follows exactly what the anthropologists have told us, and the molecular geneticists who have analyzed the human genome have told us, about where humans originated and how they spread across the planet,” according to lead researcher Curtis Brandt.

The scientists used HSV-1 for their study because it isn’t usually deadly, it’s easy to collect, and the latent infection it causes in unlucky sufferers lasts for life.

Um—but what about that one outlier American infection? It hailed from Texas, and its closest genetic relative was an Asian HSV-1 strain. Because it had genetically diverged from that Asian strain some 15,000 years ago, the researchers surmise it came from a Native American whose ancestors once walked across the Bering Strait land bridge.