Why Did Homo Sapiens Begin Forming Larger Groups Compared to Other Human Species Around 100,000 Years Ago? — Here’s What Experts Believe

Around 100,000 years ago, the modern human species, Homo sapiens, was believed to still be evolving in Africa. They later migrated out to different continents like Asia, Australia, and Europe, around 70,000 to 50,000 years ago. During this time, when most other human species like Neanderthals and Denisovans were living in smaller populations, Homo sapiens began forming larger social groups.

Living with this many individuals has its advantages and disadvantages; however, one of the key questions is what exactly is the reason why humans began forming such bigger tribes. Because this choice or adaptation may very well be the most significant reason why they were able to outcompete all the other human species to end up where we are today. So, let’s explore these ideas and questions deeper.

Brain Size and the Social Brain Hypothesis

One of the most important ideas is the social brain hypothesis. It states that humans and even other animals evolved to develop bigger brains in order to manage social relationships that make them successful as a species. This is especially observable in animals that often rely on numbers in order to survive.

For Homo sapiens, our species may have developed a larger neocortex, a part of the brain, which may have allowed us to remember or think about more people at once. In simple words, humans were social creatures that needed each other to survive.

But as our groups grew, the more our brains had to track complex social relationships like friendships, allies, enemies, and even social rules. Therefore, around 100,000 years ago, humans may have had the brain power and size necessary to belong to larger groups after millions of years of evolution of the homo genus species. This may have created a positive feedback loop, where larger groups made survival more likely, and our brains adapted in response, allowing for bigger and bigger groups.

This social brain hypothesis is a theory proposed by anthropologist Robin Dunbar, suggesting that the benefits of living in larger groups outweigh their disadvantages or costs to sustain. Evolution may have favored larger groups because it also made our brains larger with more complex cognition, giving us a higher chance of survival.

However, there are a lot more factors that influence the outcome that we live in today, so let’s look further into what could be the benefits and challenges presented by living in larger groups.

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Benefits of Living in Larger Groups

The complex evolution of homo sapiens - 1,000,000 to 30,000 years ago

So, what evolutionary advantage does living in larger groups confer that led to us having selection pressure to maintain relationships and develop bigger brains? First is the defense against predators and rival groups. Thousands of years ago, more individuals meant more eyes to look out for danger and more hands to fight off or scare threats.

Secondly, living in bigger groups also made sharing and cooperation even more powerful. It allowed humans to take on bigger, stronger, or faster animals to make their diet richer. People also shared food, knowledge, and tools, which meant that when an individual failed, they had a safety net that could still allow them to survive.

Lastly, there is cultural expansion and development. The use and teaching of language, skills, and knowledge developed faster and have a higher likelihood of being preserved and passed on to the next generation to be refined even further. This meant that more people knew what animals are dangerous, how to make tools, where to find the resources, and so on.

In much simpler words, living in larger groups made the survival of our species more likely.

Challenges Posed by Bigger Groups

Living in larger groups may have meant a higher chance of survival for an individual; however, it does bring some problems with it, too. First, more people mean more social conflict. There is intercompetition for mating, difficulty in organizing the group, especially during hunts, and the increasing demand for fairness and rules within to maintain social cohesion.

Additionally, there are theories that state that the larger the group is, the less benefit there is in helping one single person. The cooperation also tends to slow down or break off completely beyond a certain point.

Another problem was the emotional and cognitive strain that a bigger group brings. The more people one needs to try to keep track of, the higher the mental effort it requires. Larger groups put pressure on our brains to adapt and evolve.

Lastly, the physical resources needed for a larger group also increased. The bigger the group, the more food, water, and territory it needs. During tough times when resources are scarce, such as the ice ages, large groups may mismanage their assets. So, in other words, living in large social groups also has evolutionary challenges or problems that may have also influenced our species’ survival negatively.

But the main idea is that the benefits outweigh the costs. So, how exactly did Homo sapiens manage these larger groups to be the most successful human species over time?

Read more: PubMed

How Homo sapiens Managed Larger Groups

A brief overview of human evolution | HOMO HISTORY

Given the benefits and challenges, what strategies could Homo sapiens utilize in order to outweigh the cost? The first one is probably the development of language and symbolic thinking. With language, humans were able to communicate more effectively, leading to a more coordinated group, especially during hunting and gathering resources.

Another strategy could be to develop their storytelling skills and social norms that were passed down to the next generations. This may have led to the creation of their identity as a group. Shared values and knowledge passed down from their ancestors may have kept a larger group intact.

Lastly is the development of a social structured hierarchy. To deal with disputes and conflicts, individuals could have been assigned a role by themselves or the group. The more significant one contributes, the higher their hierarchy could be, leading to a more favorable result when there are conflicts.

There is also another theory called the self-domestication hypothesis of Homo sapiens, which states that our species may have evolved to be more cooperative, less aggressive, and even tolerant or resilient, which are all useful in maintaining a large social group.

In other words, the individuals who possess these traits may have been the successful ones who were able to pass on their genes to the next generation, and as a result, these characteristics became more common, allowing for larger and larger social groups over time.

Author's Final Thoughts

The Homo genus species began forming groups millions of years ago; however, Homo sapiens took it to the next level in a long and gradual process around 100,000 years ago to form a much larger social group. These changes are thought to be because of a mix of brain development, survival benefits, and the ability to handle social complexity.

Our species could have been more adept at being in larger and larger groups over the next passing generations. This may have been what caused Homo sapiens to be more successful than other human species. It is also what set the foundation for what would become a village, a city, a society, and eventually a human civilization.

Read next: Which Ice Age Predators May Have Preyed on Humans as They Spread Into Europe Around 45,000 Years Ago? — Here’s What Scientists Discovered

References & Further Reading

Benítez-Burraco, A., Clay, Z., & Kempe, V. (2020). Editorial: Self-Domestication and Human Evolution. Frontiers in Psychology. https://www.frontiersin.org/articles/10.3389/fpsyg.2020.02007/full

Shilton, D., et al. (2020). Human Social Evolution: Self-Domestication or Self-Control? Frontiers in Psychology. https://www.frontiersin.org/articles/10.3389/fpsyg.2020.00134/full

Acedo-Carmona, C., & Gomila, A. (2016). A critical review of Dunbar’s social brain hypothesis. Revista Internacional de Sociología. http://dx.doi.org/10.3989/ris.2016.74.3.037

Dunbar, R. I. M. (1998). The Social Brain Hypothesis. Evolutionary Anthropology.
https://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291520-6505%281998%296%3A5%3C178%3A%3AAID-EVAN5%3E3.0.CO%3B2-8