This detail added another layer to the story.

Denny was not just the child of two different species.

She was also evidence of a Neanderthal migration — of a movement of Neanderthal populations eastward into central Asia, into territory that had been Denisovan range.

The meeting of two worlds had literally produced a child.

What 50-50 Means In A Genome

The 50-50 proportion of Neanderthal and Denisovan ancestry in Denny’s genome is the biological equivalent of a smoking gun.

But to appreciate why, it is worth understanding what genomic ancestry proportions actually mean and how they differ between a first-generation hybrid and later descendants.