Virus study strengthens 'out of Africa' human origins hypothesis

The "out of Africa" theory of ancient human origins has been bolstered by a study of the full genetic code of a common human virus, U.S. researchers say. The findings offer new support for the assumption our ancestors emerged from Africa roughly 150,000 to 200,000 years ago and then spread eastward toward Asia and westward toward Europe, a theory already tested by anthropologists and studies of the human genome, scientists at the University of Wisconsin-Madison report. Medical microbiology Professor Curtis Brand and UW colleagues compared 31 strains of herpes simplex virus type 1 (HSV-1), which usually causes nothing more severe than cold sores around the mouth, collected in North America, Europe, Africa and Asia. "The result was fairly stunning," Brandt said. "The viral strains sort exactly as you would predict based on sequencing of human genomes," he said. "We found that all of the African isolates cluster together, all the virus from the Far East, Korea, Japan, China clustered together, all the viruses in Europe and America, with one exception, clustered together." The "family tree" of the HSV-1 virus paralleled existing analyses of human migration, the researchers said. "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," Brandt said.