Biology Now, 2e

Neanderthal Sex ■ 319

Figure 17.16

Neanderthal-human hybrid

Paleontological reconstruction of a Neanderthal-human hybrid.

the jaw appeared to be something of a hybrid

between a Neanderthal and a modern human.

“This, in my view, could only be a sign of inter-

breeding,” says Condemi.

To back up her hypothesis, Condemi’s team

analyzed the fossil’s DNA. The fossil had Nean-

derthal mitochondrial DNA, confirming that at

least the individual’s mother was a Neanderthal.

From the DNA and imaging evidence, Condemi

and her team concluded that it was the child of

a “female Neanderthal who mated with a male

Homo sapiens” (Figure 17.16). What’s more, she

added, this evidence supports the idea of a slow

transition from Neanderthals to anatomically

modern humans, in which the two species inter-

mingled in both culture and sex, rather than the

abrupt extinction of Neanderthals when modern

humans arrived.

It is unlikely that Condemi’s finding will be

the last word on Neanderthal-human inter-

breeding. In 2016, the first in-depth genetic

analysis of a Neanderthal Y chromosome

revealed mutations in genes on the Neander-

thal chromosome that would have been incom-

patible with comparable genes in the modern

human Y chromosome. In other words, these

Y chromosome mutations could have discour-

aged or pre vented the formation of a hybrid

Neanderthal–modern human species.

An even bigger question lingers for future

scientists: While modern humans continued to

develop their culture and populate the planet,

Neanderthals went extinct. Why? Perhaps another

pile of bones will someday reveal the answer.