At least two hominin lineages, Neanderthals and modern-day humans, evolved large brains, and both appear to have mastered fire, cooked, worn clothes, developed language, produced art, made jewellery, constructed musical instruments, used medicinal plants and cared for the sick and injured. Neanderthals lived in the forested areas of Eurasia between 430,000 and 40,000 years ago and were well adapted to the cold winters they experienced. They were stockier than modern-day humans, a characteristic that may have helped them retain body heat during winter, but which may also have enabled them to sprint quickly when hunting. They were top of the food chain, able to successfully hunt mammoths, bison and other large herbivores, but they also ate smaller animals, plants, fruits and nuts. At least some individuals had larger brains than modern-day humans, but we too may have smaller brains than the first humans. Perhaps we are not as smart as once we were, or, alternatively, our brains may have become more efficient.
Neanderthals are usually thought of as primitive, thuggish cavemen who were easily outsmarted by our ancestors. Careful examination of Neanderthal sites reveals a different story, and as palaeontologists have studied Neanderthal tools, jewellery made from shells, a flute, the ash of hearths in caves and their anatomy, it has become clear that intelligent apes have evolved more than once. Neanderthals lived at low densities, and their total population size may never have exceeded a few tens of thousands of individuals, but such low densities are not unusual for top carnivores. Meat was an important component of their diet, and the availability of prey could have prevented them from achieving larger population sizes, as carnivorous species tend to live at lower population densities than those that eat more vegetation. Despite their low densities, at times different groups met and likely traded objects, food, innovations and ideas. The creation of art, jewellery and music reveals what psychologists called symbolic thought, the ability to use words and pictures to represent objects or events that are not currently happening. Neanderthals were not stupid.
As well as being able to think in an abstract manner, Neanderthals also modified their environment and may have kept gardens. In a site near Leipzig, Germany, archaeologists have uncovered over 20 hectares of land that were kept deliberately open by Neanderthals for over 2,000 years approximately 125,000 years ago. It is not clear whether the site was deliberately cleared by Neanderthals, or if a natural event led to its clearance, but the vegetation record includes species that only grow in open areas, and the site is archaeologically important, with the area littered with evidence of Neanderthal activity spanning two millennia. The surrounding area was forested, and if the Neanderthals had not kept it open it would have reverted to forest in a few decades. We do not know why they kept it open, but it was a deliberate action that continued for twenty centuries, so the reason must have been important to them.
Neanderthals also produced the first known cave paintings, beating modern-day humans by about 20,000 years. The site of these 65,000-year-old paintings is near Santander in north Spain, and the art consists of black and red handprints and hand stencils, depictions of animals, and various other lines and shapes that are harder to interpret. By way of comparison, the oldest known Homo sapiens art is a life-sized painting of a pig painted 45,000 years ago in Indonesia.
Throughout the course of humanity’s history, we have tended to consider ourselves as the centre of everything and to be more developed than other life forms. Humans used to assume that the Earth was the centre of the universe, and everything revolved around it. That proved to be wrong, as the Earth orbits the sun, so we made the sun the centre of the universe, but that too was wrong. We now know we are on a planet orbiting an average star, towards the edge of an average galaxy, that may contain as many as a trillion planets. Despite this, we often still see ourselves as the pinnacle of evolution, with no other species having evolved language or intelligence, either on Earth or perhaps anywhere else in the universe. It turns out that this bastion of our uniqueness is also crumbling. Two types of intelligent ape evolved on our home planet, although they did share a common ancestor in Homo erectus.
If Neanderthals were so smart, why did they go extinct? Their extinction occurs shortly after Homo sapiens settled in Europe, so it seems we might take some responsibility. But as is often the case, events are a little more complex. Homo sapiens first left Africa sometime between 177,000 and 210,000 years ago, with fossils from this period unearthed in Greece and Israel. They did not thrive in Europe, though, and subsequently died out, possibly being unable to compete with the local Neanderthal populations. A second, more successful dispersal attempt out of Africa occurred 60,000 to 70,000 years ago, with people crossing into what is now the Middle East and working their way around the coast of Asia to Oceania. These Homo sapiens made quick progress, with the first modern humans crossing into Australia at least 40,000 years ago, and perhaps as early as 60,000 years ago, but Homo sapiens were not to successfully spread through Europe until 40,000 years ago. Did they not know it was there? Did they not like the look of it? Or did attempts made between 40,000 and 60,000 years ago to move into Europe fail?
The fossil record that palaeontologists have discovered cannot answer these questions. My suspicion is that something prevented humans from colonizing Europe earlier, and that it may have been that Neanderthals were better adapted for life in Europe than Homo sapiens. Those early humans that tried were not able to thrive given the competition they met from the resident Neanderthals, encountering similar resistance to the first wave of the Homo sapiens that left Africa. However, eventually something changed, and Homo sapiens were able to make progress into Europe, and that something was the climate.
Homo sapiens were well adapted to the hotter, but sometimes drier, environments of Africa, while Neanderthals were specialized to live in the forests of Europe. Homo sapiens were the intelligent tropical ape, and Neanderthals were their smart, temperate cousins. Changing climate between 45,000 and 40,000 years ago brought a drier spell to Europe, and this altered the environment, tipping the balance in favour of humans over Neanderthals. As humans spread through Europe, Neanderthals died out. The exact cause is unknown, with arguments made for disease, competition from Homo sapiens, decreasing populations of the large game Neanderthals relied upon, and even inbreeding. Although the last Neanderthal died forty millennia ago, their genes live on. As our ancestors spread through Europe they interbred with Neanderthals, and these genes may have provided some advantage, as they have remained within human populations to this day.
The fact that Neanderthals and modern humans interbred reveals they viewed members of the other group as potential mates. We do not know whether matings were consensual or forced, or whether humans and Neanderthals formed pair bonds. They would not have spoken the same language, having evolved apart for thousands of years, but given they both had the ability to learn languages it is not beyond the realm of possibility that they jointly raised young. Unless we find remains of a blended family we may never know, but what is clear is that children born of Neanderthal–Homo sapiens matings became parents themselves. If they didn’t, there would be no Neanderthal genes to be found in the genomes of modern-day people. The human genomics company 23 & Me reports that I am more Neanderthal than over 80 per cent of people who have used the company to be genetically profiled. I’d love to know how I’d have turned out without those genes.