What killed off the Neanderthals? Disease may have been part of it, and it may have actually been carried to Neanderthals by humans. Scientists found that Neanderthals across Europe may have been infected with diseases carried out of Africa by waves of anatomically modern humans.
"Humans migrating out of Africa would have been a significant reservoir of tropical diseases," said Charlotte Houldcroft from the University of Cambridge's Division of Biological Anthropology. "For the Neanderthal population of Eurasia, adapted to that geographical infectious disease environment, exposure to new pathogens carried out of Africa may have been catastrophic."
In this latest study, researchers reviewed the latest evidence from pathogen genomes and DNA from ancient bones. This revealed that some infectious diseases are likely many thousands of years older than previously believed. This may mean they were around when humans and Neanderthals first made contact.
Previous findings have shown that infectious disease largely exploded during the beginning of agriculture about 8,000 years ago. This was when populations became increasingly dense and sedentary human populations coexisted with livestock. Now, though, researchers have found that disease appeared much earlier. In fact, many diseases traditionally thought to be transferred from herd animals to humans, such as tuberculosis, were actually transmitted to livestock from humans.
There's already evidence that humans interbred with Neanderthals. This means that it's very likely that humans also spread disease to Neanderthals. It looks as if viruses were transferred to humans from other hominins while still in Africa, so it's possible that humans then transferred these diseases to Neanderthals.
But what kind of diseases did humans pass along? It's possible that these diseases included tapeworm, tuberculosis, stomach ulcers and types of herpes. These diseases could have weakened Neanderthals, making them less able to find food. This, in turn, may have eventually helped lead to their extinction.
"However, it is unlikely to have been similar to Columbus bringing disease into America and decimating native populations," Houldcroft said. "It's more likely that small bands of Neanderthals each had their own infection disasters, weakening the group and tipping the balance against survival."
The findings reveal a bit more about how humans may have spread disease to Neanderthals. This is important to note since researchers still don't know the exact cause of Neanderthal extinction and this could have contributed to it.
The findings were published in the April edition of the journal American Journal of Physical Anthropology.
