The Ancient Girl Whose DNA Revealed Her Parents Were Two Different Human Species

Isolated populations could come into contact during expansions and separate again during contractions.

The history of Neanderthal-Denisovan contact is likely embedded in this climate history — encounters happening during periods of range expansion or contraction, with the genetic signature of those encounters carried forward in the populations that survived.

The specific climate context of 90,000 years ago — and whether it was a period of expansion or contraction that brought Denny’s parents together — cannot be determined from the current evidence.

But understanding climate as a driver of ancient human movement and contact is essential for making sense of the patterns of interaction that Denny and the broader genetic evidence document.