This article was originally published on June 11, 2021.
Neanderthals may be our closest evolutionary cousins. They walked on two legs like us, used tools, and may have created art and music. Hominids used fire and probably lived and hunted in complex social groups similar to how they did in the Stone Age Homo sapiens did at about the same time.
We’re not quite sure when Neanderthals first began to diverge from their own primate ancestors, but the fossil record tells us that Neanderthals definitely existed around 200,000 years ago. They went extinct about 40,000 years ago when anatomically modern humans began moving into Europe.
“I wouldn’t say Neanderthals died out – because you and I both have Neanderthal DNA in us,” says William Banks, an archaeologist at France’s National Center for Scientific Research. “They haven’t essentially disappeared without leaving their mark.”
But given the difficulty of interpreting fossils, scientists are divided on why these close cousins and quasi-ancestors of many modern humans no longer walk the Earth. Many believe that modern humans predated the Neanderthals, which eventually led to the extinction of the Neanderthals. This competition may have favored today’s version of humans because of superior technology, better immunity to disease, or minor differences in Neanderthal social habits. H. sapiens they may also have been better equipped to deal with a changing climate.
“You end up with one population displacing the other,” Banks says.
Why did Neanderthals disappear?
Neanderthals, so named because the first known fossils of the species were found in 1856 in Germany Neander Valley, lived widely in Eurasia. They were a few inches shorter than H. sapiens of time as well as a little wider.
Archaeologists have found Neanderthal fossils from the Altai Mountains in Central Asia to Southwest Asia and across Europe. These archaic humans and their evolutionary ancestors are the only known hominids to have inhabited Europe before modern humans. H. sapiens began to make significant inroads into the continent about 42,000 years ago, although few fossils from earlier periods have been found.
The period of overlap between modern humans and Neanderthals was relatively short, lasting about 3,000 to 4,000 years, Banks says. The radiocarbon dating technique commonly used to determine the age of fossils has a margin of error of 500 years, so it is difficult to get precise dates on what happened to many of the fossil remains that archaeologists have found since this period.
The tools for success: Neanderthal extinction through competition
Many researchers believe that advanced hunting weapons or other tools may have helped humans overtake the Neanderthals. Neanderthals are known to have used basic spearheads, axes and other tools that were often cut on only one side of the blade, known as Mousterian. Meanwhile, humans had technology, often focused on knife-like blades, which may have allowed for greater precision in certain uses.
Banks isn’t sure those inconsistencies made the difference. He says researchers must be careful not to approach the question of Neanderthal extinction with the automatic assumption that humans were somehow superior.
“We really need to pay attention to remove the bias,” he says, adding that it is difficult to determine whether any difference in intelligence played a factor in the Neanderthals’ demise. For example, cave art found in Spain has been dated to a period before modern humans are known to have been present in the area. Archaeologists also claim that our evolutionary cousins made music based on the discovery of what may have been remains of a flute found in a Neanderthal context. Banks adds that Neanderthals made personal ornaments from raptor claws and used ocher to produce pigments for possibly symbolic purposes. Some archaeologists don’t accept that Neanderthals were capable of doing this, and others think it could be the case that they learned from modern humans, Banks says, although he doesn’t subscribe to the latter view.
“From what I can see, Neanderthals are incredibly complex behaviorally,” he says.
Extinction of the Neanderthals by pandemic
Noah Rosenberg, a professor of biology at Stanford University, believes that disease may have played a major role in the extinction of the Neanderthals. In a recent study published in Nature CommunicationsRosenberg and his co-authors built a mathematical model on the dynamics of the disease that occurs when two separate populations come into contact.
When European colonists first arrived in what is now the Americas, the diseases they brought were destroyed approximately 90 percent of the indigenous population in North, Central, and South America. In this case, Europeans contracted a greater number of diseases due to higher population density and more domesticated animals, and subsequently developed some resistance that the Native American population did not have.
Although humans had not yet domesticated animals before 42,000 years ago, Rosenberg suggests that something similar may have happened when humans began interacting with Neanderthals. Both hominids exchanged packages of pathogens when they met, but one may have influenced the other species more than the other. Over the generations, death may have caused the boundary between humans and Neanderthals to shift.
Using the known fossil record, the models Rosenberg and his colleagues ran showed that the shifting boundaries between the two species in the Levant (along the eastern Mediterranean) could be fairly well explained by the gradual loss of the Neanderthal population due to disease. It is not clear what diseases these may have been and why humans had greater resistance, but he suggested that this may be due to a greater suite of pathogens existing in the tropical regions from which humans migrated.
“I wouldn’t say it’s the only factor, or even that it’s the most likely factor,” Rosenberg says. “Just by imagining the transmission of an infectious disease between Neanderthals and humans, you can explain something that has not been explained.”
The multi-factor theory of the Neanderthal extinction
Banks believes that disease, competition in one form or another, different responses to a changing climate and environment, and resource use may have played an important role in the extinction of the Neanderthals. Indeed, each of these factors probably played a role in different areas and at different times during the millennia of coexistence.
There were probably a huge number of diverse types of interactions that occurred between the two types of hominid, he says—just as there are between humans today. The advantage may even come down to something as simple as a difference in how Neanderthals responded to external changes in the environment and climate.
IN a region that Banks studied in France, Neanderthals continued to use the same territories despite the large-scale changes in climate and environment that occurred about 70,000 years ago. “They’re sort of the original home fixtures, if you want to call it that,” he says.
To stay in the region, Banks says Neanderthals created new stone technologies suited to the changing environment. “They have this capacity just like modern humans to innovate technologically and adapt to their conditions,” he says.
This population may not represent the habits of Neanderthals as a whole. But Neanderthals may have been more likely than modern humans to remain stationary over generations with smaller social networks. These different movement patterns may have made the difference, according to The work of banks. Smaller networks may also have led to smaller gene pools, some research suggests inbreeding is relatively common among Neanderthals at least in some areas.
“You have these very complex and intelligent populations, but there’s only a small difference in how they organize themselves in the landscape that makes the difference,” says Banks.
We will continue to learn more about these factors as archaeological techniques improve, helping us to revisit excavated sites and better analyze newly discovered remains. But Banks says this is likely to further complicate the question of what caused Neanderthal extinction, rather than giving us a definitive answer.
“I really don’t think we’ll ever find the answer by saying, ‘This was one factor and this factor tipped the scales,'” says Banks.