Why did humans take over the world while our closest relatives, the Neanderthals, went extinct? It’s possible that we were simply smarter, but there is surprisingly little evidence that this is true.
Neanderthals had large brains, language and advanced tools. They made art and jewelry. They were clever and suggested a curious possibility. Perhaps the crucial differences were not at the individual level, but in our societies.
Two hundred and fifty thousand years ago, Europe and Western Asia were Neanderthal countries. Homo sapiens inhabited southern Africa. Estimates vary, but perhaps as early as 100,000 years ago, modern humans migrated out of Africa.
Forty thousand years ago, Neanderthals disappeared from Asia and Europe and were replaced by humans. Their slow, inevitable replacement suggests that humans had an advantage, but not what it was.
Anthropologists once saw Neanderthals as dull brutes. But recent archaeological discoveries show that they rivaled us in intelligence.
Neanderthals mastered fire before we did. They were deadly hunters, taking large game such as mammoths and woolly rhinos and small animals such as rabbits and birds.
They collected plants, seeds and shellfish. Hunting and foraging all these species required a deep understanding of nature.
Neanderthals also had a sense of beauty and made beads and cave paintings. They were spiritual people who buried their dead with flowers.
Stone circles found in caves may be Neanderthal sanctuaries. Like modern hunter-gatherers, Neanderthals’ lives were likely steeped in superstition and magic; their skies full of gods, the caves inhabited by ancestral spirits.
Then there’s the fact that Homo sapiens and Neanderthals had children together. We weren’t that different. But we have met Neanderthals many times, over many millennia, always with the same result. They disappeared. We stayed.
The hunter-gatherer society
It may be that the most important differences were less significant at the individual level than at the societal level. It is impossible to understand people individually, any more than you can understand a honey bee without looking at its colony. We value our individuality, but our survival is tied to larger social groups, just as the fate of a bee depends on the survival of the colony.
Modern hunter-gatherers give us the best estimate of how early humans and Neanderthals lived. People like the Khoisan of Namibia and the Hadzabe of Tanzania gather families into wandering groups of ten to sixty people. The bands together form a loosely organized tribe of a thousand or more people.
These tribes have no hierarchical structures, but are linked by a shared language and religion, marriages, kinships and friendships. Neanderthal societies may have been similar, but with one crucial difference: smaller social groups.
Close-knit trunks
What this points to is evidence that Neanderthals had lower genetic diversity.
In small populations, genes are easily lost. If one in ten people carries a gene for curly hair, then in a group of ten people, one death could remove the gene from the population. In a group of fifty, five people would be carriers of the gene – multiple backup copies. So over time, small groups tend to lose genetic variation, ultimately leaving them with fewer genes.
In 2022, DNA was recovered from the bones and teeth of eleven Neanderthals found in a cave in the Altai Mountains in Siberia. Several individuals were related, including a father and a daughter – they came from a single bond. And they showed low genetic diversity.
Because we inherit two sets of chromosomes – one from our mother and one from our father – we carry two copies of each gene. We often have two different versions of a gene. You may get a gene for blue eyes from your mother and a gene for brown eyes from your father.
But the Altai Neanderthals often had one version of each gene. As the research shows, this low diversity indicates that they lived in small groups – probably with an average of just 20 people.
It is possible that Neanderthal anatomy favored small groups. Because they were robust and muscular, Neanderthals were heavier than us. So each Neanderthal needed more food, which meant the land could support fewer Neanderthals than Homo sapiens.
And the Neanderthals may have mainly eaten meat. Meat eaters would get fewer calories from the land than people who ate meat and plants, again leading to smaller populations.
Group size is important
If humans lived in larger groups than Neanderthals, this could have benefited us.
Neanderthals, strong and skilled with spears, were probably good fighters. Lightly built people probably responded by using bows to attack from a distance.
But even if Neanderthals and humans were equally dangerous in battle, if humans also had a numerical advantage, they could bring more fighters and absorb more losses.
Large societies have other, more subtle advantages. Bigger bands have more brains. More brains to solve problems, remember knowledge about animals and plants, and techniques for making tools and sewing clothes. Just as large groups have greater genetic diversity, they will also have greater diversity of ideas.
And more people means more connections. Network connections increase exponentially with network size, according to Metcalfe’s law. A band of 20 people has 190 possible connections between its members, while 60 people have 1770 possible connections.
Information flows through these connections: news about people and animal movements; tool making techniques; and words, songs and myths. Moreover, the behavior of the group is becoming increasingly complex.
Think of ants. Individually, ants are not smart. But interactions between millions of ants allow colonies to build elaborate nests, forage for food and kill animals many times larger than an ant. In the same way, human groups do things that no one can do: design buildings and cars, write elaborate computer programs, fight wars, run companies and countries.
Humans are not unique in having large brains (whales and elephants do) or having huge social groups (zebras and wildebeest form huge herds). But we are unique in combining them.
To paraphrase poet John Dunne, no man – and no Neanderthal – is an island. We are all part of something bigger. And throughout history, people formed larger and larger social groups: groups, tribes, cities, nation states, international alliances.
It may be that the ability to build large social structures gave Homo sapiens an advantage over nature and other hominids.
Nicholas R. Longrich, Senior Lecturer in Paleontology and Evolutionary Biology, Life Sciences at the University of Bath.
This article is republished from The conversation under a Creative Commons license. Read the original article.
