Beatrice Everall discusses where the Neanderthals disappeared to and the impact they’ve had on modern humans.
Neanderthals are commonly thought of as mysterious cave men that were around at the time of our ancestors, but much more has been discovered about these pale, hairy people in the last few years. Let’s start with the basics of what we know. Modern Humans first migrated out of Africa 50,000 years ago, whereas Neanderthals first emerged into Europe 400,000 years ago, as the first evidence of Homo neanderthalensis appeared around that time. The appearance of modern humans was what lead to the extinction of Neanderthals, as shortly after we arrived, all traces of them disappeared. Many belongings and remnants were found of our evolutionary cousins in Asia and Europe, but these disappeared around 40,000 years ago – approximately 10,000 years after modern humans migrated out of Africa. It is a common theory that modern humans competed with Neanderthals for resources such as food and shelter, and due to our superior intellect we outcompeted them; however recent findings have actually favoured the theory that instead of beating them in competition, in reality we just outlasted them.
Researchers found that cold/dry periods coincided with an apparent disappearance of Homo neanderthalensis in different parts of the continent, followed by the appearance of our species, Homo sapiens. Scientists have long debated what lead to the disappearance of Neanderthals, and some have blamed the change in climate, while others theorised epidemics or competition for resources was to blame. Their study highlighted two cold and dry periods, one 44,000 years ago and the other roughly 40,000 years ago, and they noted that ‘the timing of those events matches the periods when artefacts from Neanderthals disappear and signs of Homo sapiens appear’. As Homo sapiens were likely better adapted for such dry climates after living in Africa, it is likely they were able to survive in this environment and after the death of Neanderthals, would have had more resources available to thrive.
Neanderthals were not extinct when modern humans first moved out of Africa and into Europe, as there has been evidence of interbreeding between the two species. Two recent studies have shown that collectively, the Neanderthal DNA percentage in modern humans today is about 20%; meaning 20% of the Neanderthal genome can be found throughout modern humans today. Many Europeans’ DNA is 2-4% Neanderthal DNA. Those genes have an influence on a range of areas: hair, skin, and disease susceptibility. Neanderthal DNA is more present in certain races than others; completely absent from some parts of non-African genomes but rampant in others. Advantageous genes were passed on and kept in the human genome. Skin colour and keratin genes are mostly from Neanderthal DNA- it is likely that pale skin was a trait they developed and passed onto modern humans. Both studies found some regions of our DNA lack any Neanderthal DNA, such as ones involved in motor coordination, the testes, and the X chromosome. The fact the modern humans and Neanderthals mated is interesting due to its implications – it means that not only were we able to peacefully able to coincide with each other, but it gives concrete evidence that Neanderthals were still alive when humans moved out of Africa.
Recent findings show that human traits did not stay in the Neanderthal gene pool. This was shown by the sequencing of the last group of Neanderthal remains found, from around 40,000 years ago. These Neanderthals were descended from Neanderthals from the Altai mountains, who were some of the individuals that mated with Homo sapiens when they moved out of Africa. Therefore, no modern human DNA in their genome indicated that they did not inherit any of the Homo sapien DNA, for reasons that can only be speculated. However, this example of one-way gene flow could also lead to another theory for the disappearance of Neanderthals. The Neanderthals could have possible mated with modern humans extensively and became incorporated into modern human populations, with mainly modern human genes being passed on as they were more advantageous, and Neanderthal DNA being lost.
A widely common conception of Homo neanderthalensis is that they were not intelligent and lacked many skills that modern humans had at that time. However, new research shows that Neanderthals were able to start fires using stone tools. There are also findings indicating that Neanderthals could make audible sounds and possibly communicate with each other. These cultural traits of fire and speech show that Neanderthals were possibly smarter than previously thought, as speech requires a large forebrain with specialisation in certain areas of the brain to allow for comprehension and smooth facial muscle movements. Scientists are growing mini Neanderthal brains to compare to human brains and to hopefully find out more about our distant cousins and the way they saw the world. The Neanderoid neurons make fewer synaptic connections, creating what resembles an abnormal neuronal network. Several of these differences mirror what a scientist, Alysson Muotri, has found studying neuronal development in the brains of children with autism. Research in this area is trying to find what makes modern humans so cognitively special, or possibly even prove that we aren’t so special after all.