Why did the Neanderthals go extinct?, asks Richard Collins
They lived in Europe and Asia for hundreds of thousands of years and must have been superbly adapted to their environment. Yet, around 30,000 years ago, they vanished completely. How odd that, while our species became so spectacularly successful, their species failed?
Anthropologists have tried to explain what happened but no completely satisfactory theory has emerged. Now a new suggestion has been put forward. Anthony Santino Pagano and colleagues at SUNY Downstate University claim that these ancient people were especially prone to ear infections and that this was a crucial factor in their demise.
Neanderthals were physically stronger and more heavily-built than we are. They mastered fire, fashioned tools and had brains as big as ours. About 45,000 years ago modern humans, our ancestors, arrived from Africa. How the natives and the newcomers regarded each other we will never know, but the two may have competed for scarce resources.
Did this lead to violent conflict and, eventually, to genocide? If so, some Neanderthals should have retreated, in ‘to hell or to Connacht’ style, to areas where their enemies didn’t go or couldn’t compete.
In modern times, the arrival of Europeans caused pandemics in the Americas. Did similar infectious diseases, perhaps introduced by our ancestors from Africa, wipe out the Neanderthals? Again, individuals with natural immunity would surely have survived such plagues. DNA analyses show that we modern Europeans carry Neanderthal genes. Did enough interbreeding take place to absorb their race completely?
If so, the Neanderthals are not extinct; they live on in us, which seems unlikely. The Eustachian tubes, 35mm long in adults, run from the middle ear to the back of the nose. When an aeroplane climbs, passengers experience a bubbling sensation in their ears as the air in their tubes expands with the pressure drop.
Small children’s tubes run at ‘a flat angle’ which means that bacteria multiply in fluids within them, leading to chronic ear infections, the bane of parents’ lives. From the age of six onwards, the tube angle inclines upwards, allowing the system to drain. Ear infections become less frequent from then on.
Pagano’s team of anatomists and anthropologists have managed to reconstruct the Neanderthal ear. They discovered that the Eustachian tubes of these ancient adults, like those of modern children, run at a flatter angle. This, the researchers argue, made even adult Neanderthals prone to life-long ear infections.
Thanks to antibiotics, we can treat infections nowadays but these afflictions would have caused intractable problems long ago; permanent hearing loss and persistent chest infections.
“This could have compromised fitness” and affected “Neanderthals ability to compete within their ecological niche”, the authors say, “potentially contributing to their rapid extinction.” Competition with modern humans, they suggest, was just the straw which broke the camel’s back.
How plausible is this suggestion? If deafness and chest-infections were such a major problem, why didn’t Neanderthals go to the wall much earlier in their history? Natural selection changed the angle of our ancestors’ Eustachian tubes. Why did it fail to do so in Neanderthals?
Anthony Santino Pagano et al. Reconstructing the Neanderthal Eustachian Tube; New Insights on Disease Susceptibility, Fitness Cost, and Extinction. The Anatomical Record. 2019.