WHAT HAPPENED TO THE NEANDERTHALS?

Until now, I focused on how changes in climate let us develop the most human of our features: walking upright and big brains. However, I also mentioned that hominins used to be very diverse – there were numerous species living on Earth at the same time. Right now Homo sapiens is the only one present. What happened?

In today’s post I will focus on a very recent example of hominin extinction - the Neanderthals. Homo neanderthalensis was a successful species for millennia - it first appeared in the fossil record about 400,000 years ago and vanished approximately 30,000 years ago, although the exact dates are still disputed (Hublin: 2009). Unsurprisingly, the debate about who the Neanderthals were, how they lived and why they went extinct is also still open.

For a very long time the scientists thought that the Neanderthals vanished because they were outcompeted by modern humans, the Homo sapiens. Modern humans are believed to have arrived to Europe, the stronghold of the Neanderthals, about 40,000-43,000 years ago, and according to this theory they competed with the Neanderthals over resources and territory (Hetherington: 2012). Homo sapiens had several advantages over Homo neanderthalsis. For example, despite many anatomical similarities, their body build allowed them to move faster. Another important advantage was modern human’s brain, which - although smaller on average – was more developed and permitted modern humans better communication or social organisation, crucial to obtaining resources and securing territories. Some other theories claim that migrating Homo sapiens brought certain pathogens to Europe which were unknown to the Neanderthals’ immune system.

One of the most recent hypotheses states that actually the Neanderthal’s extinction as such never took place. There is evidence that modern humans and the Neanderthals interbred; moreover, recent research shows that “between one and four percent of the DNA of many humans living today originate from the Neanderthals” (Max Planck Society: 2010). This might indicate that the Neanderthals did not vanish completely, but might have been “absorbed” by the dominant modern humans (Villa and Roebroeks: 2014).

However, none of the above theories mention the climatic changes that took place at the time of the Neanderthal disappearance. The Neanderthals were a very adaptable species – they were present during both glacials and interglacials. They used to inhabit south-west Eurasia and their habitat ranged from temperate woodland to tundra. They had more body hair and fat than modern humans which made it possible for them to survive in cold conditions. But new evidence shows that when the Neanderthals started vanishing, the climate was particularly harsh, and that their disappearance occurred at different times in different regions, pushing them increasingly further south. Cold and dry weather wiped out most of the Neanderthals sources of food and turned their usual habitats into vast, open spaces that they could not adapt to. Their anatomy made them very successful in wooded areas or steppes – they could, for instance, sneak up on a prey and kill it form close proximity. They could not, however, chase the prey over long distances or throw a spear from afar. Their bodies simply did not allow it. Studies lead by Professor Tom Higham from the University of Oxford indicate that when the modern humans arrived to Europe, the Neanderthals were already in decline and the new competition was just a final blow to the declining population (Higham: 2014). They also suggest that the Neanderthals and modern humans coexisted for up to 5000 years and that the disappearance of Homo neanderthalsis was a gradual process, dispelling the theories I talked about at the beginning of the post.

As usual, it is impossible to find definite answers to all the questions we might have about our very close relatives: our dating methods aren’t accurate enough, and the fossil and proxy evidence records are still far from complete. However, it is very important to continue the research: our DNA differs from the Neanderthals by only 0.12% and we can learn some important lessons from the story of their disappearance. The latest evidence suggest that, although we are such an unbelievably adaptable species, climate change might pose one of the gravest threats to our survival.