While all modern humans originated in Africa around 200,000 years ago, scientists have long debated on exactly when and how we spread across the globe. A trio of studies published this week posits that, with one tiny exception, all people living today are descended from the same wave of humans that left Africa between 50,000 and 80,000 years ago, the New York Times reports. Discover calls the research "complex, even for genomic studies," but the gist is this: While humans may have left Africa in two (or more) waves—and as early as 120,000 years ago—the populations that left early died out (either on their own or with help from subsequent waves), leaving all of us to trace our ancestry to a single wave of African migrants.
The exception to this is the natives of Papua New Guinea, at least 2% of whom show some DNA evidence of earlier migration waves, the BBC reports. Researchers found no other such evidence in hundreds of populations around the world. The most important impact of the studies, which the Times calls a "series of unprecedented genetic analyses," may be in our understanding of the human genome. To conduct the studies, researchers created high-quality genome sequences from people in more than 270 indigenous populations around the world. That information could one day help scientists understand and treat a whole host of genetic conditions.