This finding reframes the story of ancient human diversity.

We are accustomed to thinking of species as the fundamental units of biological existence — discrete, bounded categories with clear distinctions between them.

But the ancient human world was apparently more of a continuum: groups that were different enough to have distinct characteristic behaviors, tools, and perhaps even communicative abilities, but similar enough in their fundamental biology to produce viable offspring when they encountered each other.

Denny is the evidence of that continuum.