Since Homo sapiens arrived in Europe around the same time as Neanderthals became extinct around 40,000 years ago, it has been long believed that modern humans were to blame for their demise. However, according to a new study, the arrival of Homo sapiens isn’t the cause behind the extinction of Neanderthals. Instead, researchers say that inbreeding and small populations are to blame.
The study was conducted by Eindhoven University of Technology in the Netherlands and the researchers claimed, “The species’ demise might have been due merely to a stroke of bad, demographic luck.” The study was published in the PLOS One journal and can be read in full here.
Researchers took information they gathered from different studies conducted on hunter-gatherer populations and used that to simulate a model of populations in regards to Neanderthals. They also added several variables to their study which included inbreeding and reduced numbers in population (also known as the Allee effect). They were able to conclude that inbreeding alone was more than likely not the cause of their demise. On the other hand, with inbreeding, 25% or less of female Neanderthals would have given birth each year, ultimately causing a significant reduction in population totals – even causing extinctions in small populations of up to 1,000 individuals.
Krist Vaesen, who is an associate professor at Eindhoven University of Technology, told Inverse, “The mere fact that their population was small could have resulted in their extinction.” Since finding a suitable mate among such a small population would have been difficult enough, there would have also been a drop in the number of individuals who would have went out hunting for food and who would have taken care of the children.
Researchers believe that the Allee effect, in addition to inbreeding and demographic changes, caused the extinction of Neanderthals within a 10,000 year period. However, the team did say that modern humans could have played a small part in the demise of Neanderthals.
Since Neanderthals and Homo sapiens interbred, that would have caused much fewer Neanderthal-only mates. Additionally, modern humans could have interrupted the migration of Neanderthals during that time. While modern humans didn’t particularly cause the extinction of Neanderthals, they could have just sped up the process.
These, of course, are just hypotheses, as it’s not conclusively known what actually caused Neanderthals to go extinct. But according to Vaesen, their “downfall is attributed to random events, rather than to some external factors,” adding that it’s “the most parsimonious explanation for the downfall.”