The discovery of the first Neanderthal fossil in 1856 immediately raised questions about their relationship to us Homo sapiens. It would be some time before solid DNA evidence came out to suggest we interbred with them, though pre-existing skeletal analyses had suggested the possibility. Modern DNA evidence tells us that not only was there interbreeding, but a substantial amount of it.

Nailing down where this was happening has been tricky, and the DNA evidence has not been entirely helpful in this regard. The problem is that anatomically-modern humans had a long time period, and spanned a large area, where interbreeding could have taken place with Neanderthals in Europe. While that would suggest there should be a higher proportion of Neanderthal genes in European populations, the DNA evidence shows Asians have a higher proportion.

To help nail this down, forensic anthropologist Ann Ross of North Carolina State University and graduate student Kamryn Keys partnered with paleoanthropologist Steven Churchill of Duke University to apply a technique little-used in paleoanthropology: facial morphology analysis. Their results not only point to an answer to this mystery, but to a way of harvesting new data and drawing new insights from a limited fossil record.

Surprising Results

The outcome, Churchill admits, far exceeded his initial expectations: “I was like, ‘there’s no way this is going to work,’ at the outset.” There were two basic reasons for this. First, the sample…