It shows that the interbreeding between ancient human groups was not merely biologically possible but was, in at least some cases, evolutionarily beneficial to the populations that participated in it.

Modern humans who encountered Neanderthals and Denisovans did not simply survive alongside these other groups before replacing them.

They partially merged with them, incorporating genetic variants that helped them survive in the environments they encountered.

The biological diversity of our species today — the range of physical characteristics, disease resistances, and physiological adaptations that characterize different modern human populations — reflects, in part, the ancient encounters and interbreedings that produced children like Denny.

How Rare Was Denny?