The sequence showed something that had never been seen in an ancient individual before: the clear genetic signature of two completely distinct ancient human lineages, interleaved throughout the genome.

Half the DNA looked Neanderthal.

Half the DNA looked Denisovan.

The proportions were not the result of ancient admixture — the gradual mixing of populations over generations that produces small percentages of ancestry from one group in individuals primarily from another.

The proportions were approximately 50-50.

And 50-50 means one thing in genetics: first-generation hybrid.

An individual with one parent from each group.

Denny’s mother was a Neanderthal.