Modern humans (at left) and Neanderthals (right) were strikingly different in many respects. Yet a new genetic analysis suggests that Neanderthals may have had an out-of-Africa migratory experience not unlike our own.
How many Neanderthals were there?
The archaeological record suggested that very roughly 150,000 individuals spanned Europe and Asia, living in small groups of 15 to 25 — and that their total numbers fluctuated greatly during the several climate cycles (which included harsh glacial periods) that occurred during the half a million years they inhabited Earth, before going extinct 40,000 years ago.
Some gene-based estimates put the Neanderthals’ effective population at a measly 1,000; others claim they hovered at a few thousand at most (one study, for example, calculated that there were effectively fewer than 3,500 females).
Two hypotheses might account for these results: that the population was indeed that low, even at its peak, or that the population was perhaps larger but had been decreasing for a very long time.
In either case, the Neanderthals were always on the decline; their extinction seemed to have been foretold from the beginning.
The Neanderthals struggled: The glacial periods they endured and the fragmentation of their population left them unable to support robust social or technological growth. “But the one misconception people have is that we represent progress, that modern humans are the best and Neanderthals beneath us,” said John Hawks, a paleoanthropologist at the University of Wisconsin-Madison..
“When it comes to being hunters, being reliant on high-energy food resources in marginal environments, Neanderthals were the extreme.” He added, “They solved problems we don’t face today. How did they live at such low population densities for hundreds of thousands of years? That’s something we never managed.”
Before doing this research, Alan Rogers, an anthropologist and population geneticist at the University of Utah, thought Neanderthals had been on the brink of extinction when modern humans entered their territories, that their populations were already dwindling and rife with genetic disease. “I no longer think that,” he said.
Understanding the true structure of the Neanderthal population may help scientists dig deeper and more productively into the dynamics of those ancient people and their interactions with us. For example, Akey said, one new question we might ask about interbreeding between modern humans and Neanderthals is whether there were any sexual biases in that gene flow. Did we incorporate equal amounts of maternal and paternal Neanderthal DNA, or was the scale tilted?