The result would be approximately 75 percent Neanderthal ancestry and 25 percent Denisovan ancestry.

Each subsequent generation of interbreeding with one of the parental groups dilutes the contribution of the other.

After several generations, what remains of the minority ancestry is a small fraction — 12.5 percent, then 6.25 percent, then 3 percent, and so on, halving with each generation.

The modern human signature of Neanderthal ancestry — approximately 1 to 3 percent of the genome — represents the diluted result of many generations of interbreeding between the initial hybrid individuals and the modern human population.

Those percentages are too small to be the product of recent, direct interbreeding; they are the accumulated legacy of encounters that happened tens of thousands of years ago, diluted by many subsequent generations of reproduction with modern human partners.