How Our Ancestors Could Have Killed off the Neanderthals

How Neanderthals made tar discovered by scientists. NIKOLA SOLIC/REUTERS

In an argument that takes the phrase "culture wars" to a new level, a group of researchers says it's possible that cultural superiority gave human ancestors the upper hand over their Neanderthal cousins.

Neanderthals lived in what is now Europe for hundreds of thousands of years before humans arrived. Last year, researchers dated the oldest human skull found outside of Africa, in Manot Cave in Israel, to 55,000 years old. That marks the known start to a time when the two hominids lived side by side, a period likely full of interaction and competition for food and other resources. By 45,000 years ago, humans had arrived in Europe. Some 5,000 years later, the Neanderthals were extinct.

Archaeologists are in two camps over what exactly happened. Some believe the Neanderthals died off because of climate change or epidemics. Others think modern humans wiped them out with better tools, clothing or social organization.

In a paper published today in Proceedings of the National Academy of Sciences, three researchers led by Stanford University biology professor Marcus Feldman argue that those technological and cultural advances could have been the tipping point. The team modified a mathematical model frequently used to predict competition between populations and added, for the first time, new dimensions for cultural advantage and the ability to learn.

They set the model so that the more culturally advanced a group was, the larger it could grow. Because humans were spreading into Neanderthal territory, it's likely that those leading the charge arrived in small numbers, compared with the established Neanderthals. Despite this disadvantage, the cultural skills they brought with them could have allowed them to hunt, settle land and otherwise use resources more efficiently than the original residents. Eventually, their numbers would swell, making them even more powerful.

"If the culture is there, what our paper shows is that a smaller number of anatomically modern humans could overwhelm a much larger Neanderthal population that did not have culture," says Feldman. "The more culture, the smaller the group needs to be." If the culture levels were very different, the humans could have started with half as many people and still win out.

It's not a question of humans being smarter than Neanderthals, says Feldman, who points to studies suggesting the two species had similar brainpower, a genetic trait that grows slowly through evolution. It's that they had more tools and clothes and a more complex social organization—technology that spreads much more rapidly from person to person, especially when coupled with superior learning abilities.

Not everyone agrees that this difference existed. In a 2014 paper in the journal PLOS ONE , Paola Villa of the University of Colorado, Boulder, and Wil Roebroeks of Leiden University in the Netherlands reviewed various arguments for human cultural superiority and found them lacking. "We have found no data in support of the supposed technological, social and cognitive inferiority of Neanderthals," they wrote. The suggested that the extinction resulted from a combination of factors.

Rather than settle the debate over humankind's 15,000-year conquest of the Middle East and Europe, Feldman's model merely tests the plausibility of the cultural argument. It's a way of trying to tie together what archaeologists have uncovered and point to new things they might look for in the field.

One thing that would improve the model, Feldman says, would be a measure of the speed at which anatomically modern humans could have spread across the continent. "We'd like to see the geographic trajectory—how much migration there would have to be and at what pace it would have to happen to reconstruct what geologists tell us."