The two copies of her chromosomes differed from each other at a rate consistent with having been inherited from populations that had been separated for hundreds of thousands of years — exactly what would be expected if one chromosome came from a Neanderthal and the other from a Denisovan.

This is not a result that requires subtle statistical analysis or complex inference.

It is written directly in the sequence of Denny’s genome, visible to any researcher who knows what to look for.

The chromosome-level evidence for Denny’s first-generation hybrid status is as direct as ancient DNA evidence can possibly be.

The World Before Modern Humans Arrived

To truly appreciate what Denny’s world was like, it helps to think about what the ancient human world looked like approximately 90,000 years ago — the world before modern humans had expanded out of Africa in significant numbers.

At that time, the geography of human habitation was dramatically different from today.