The statistical analysis of the signals in ancient and modern genomes tends to suggest the latter: that interbreeding, while not continuous or ubiquitous, was frequent enough to produce the genetic signals we see.

If that is the case, there were many children like Denny in the ancient world — children born to parents from different ancient human groups, living in the zones where those groups overlapped, contributing their mixed ancestry to the next generation.

We may never find another one as clear as Denny.

The conditions for first-generation hybrid identification — 50-50 ancestry proportions, confirmed through chromosome-level analysis — require both exceptional preservation of the specimen and a high coverage of the resulting genome.

Most ancient specimens, even from sites with good preservation, do not yield the quality of data needed for such precise analysis.