For decades, two competing models of human evolution have dominated the field. One claims that H. sapiens evolved in a single place, Africa, and left that continent only fairly recently; the other suggests that our species evolved in multiple regions across both Africa and Eurasia.

While debate between proponents of the two models rages on, there’s one big problem: Researchers keep finding fossil and genomic evidence that don’t fit either model.

A paleoanthropological review published in Science in December acknowledged that the evidence had reached a tipping point. It’s time, the authors said, for a new model of how our species evolved and spread across the world. But how does this new model compare with its predecessors?