There are few phenomena in the world that vary as widely as human nature.

On the one hand, our greed and self interest seem to know no limits – with countless examples of individuals exploiting others (and the planet) for material gain.

E.g. The Military Industrial Complex, bankers taking billions in bonuses following the financial collapse of 2008, and the destruction of the Amazon Rainforest for profit.

On the other, our capacity for cooperation is equally as extraordinary; enabling us to walk on the moon, save billions of lives through modern medicine, and end segregation in America and Apartheid in South Africa.

Moreover, some even devote their entire lives in the service of others, as in the cases of Mother Teresa and Mahatma Gandhi.

So what gives?

How we can we explain this strange paradox of human nature?

Until recently, questions like this were confined to the domains of religion and philosophy, and outside the remit of scientific thinking.

However, new developments in evolutionary science are now beginning to help us answer these questions from a scientific point of view.

In this post, we’ll explore what evolutionary theory can tell us about human nature, and what insight it can offer as to whether our most basic nature is more like that of a greedy banker, or that of a Mother Teresa.

But first, let’s briefly consider why this is important.


Our Worldview Becomes a Self-Fulfilling Prophecy

Our view of human nature shapes both how we see ourselves and the world we live in.

When Darwin published On the Origin of Species in 1859, it fundamentally changed our worldview.

We were no longer the central actors in a divine creator’s plan.

Instead, we suddenly found ourselves to be an insignificant primate in a vast, automatic and indifferent universe. The dominant world view now became ‘survival of the fittest’, with each individual out for his or her own good.

This is important because our worldview can become a self-fulfilling prophecy.

In other words, if I think that human nature is fundamentally selfish and that everyone else is out for their own good, then that is likely how I am to act too.

If, on the other hand, I have the sense that human nature is basically good and that I am a member of a cooperative species, then I am likely to act in a more prosocial way towards others. I’m probably going to trust other people more too, and generally just feel safer in day-to-day life.

Indeed, the ‘Perception Matters’ Common Cause UK Value Survey surveyed a representative sample of 1,000 citizens and found that 77% of respondents believed that their fellow citizens placed more importance on selfish values than compassionate ones.

Moreover, those who believed that their fellow citizens were selfish reported greater social alienation, felt less responsible for their communities, and significantly less positive about voting, volunteering and joining meetings.

So, from an evolutionary point of view, which of the two (selfish or selfless) is the more accurate representation of human nature?

To answer this, we first need to understand Darwin’s theory of natural selection.


The Best Idea Anyone Ever Had?

“Enhanced fitness compared to alternative traits is the only source of design in nature.” – David Sloan Wilson

In his 1995 book: Darwin’s Dangerous Idea, Philosopher Daniel Dennett argues that Darwin’s theory of natural selection was “the single best idea anyone ever had”.

Dennett goes on: “In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning and purpose with the realm of space and time, cause and effect, mechanism and physical law”.

So, what exactly was Darwin’s insight, and how can it help us better understand human nature?

For natural selection to work, all that is required are the following three elements:

First, that individuals vary in their traits (variation).

Second, that these variations have consequences for fitness (i.e., an individual’s ability to survive and reproduce) in a particular environment (selection).

And third, that successful parents pass on their traits to the next generation (retention).

That’s it…

Although natural selection is usually a slow process, there are some instances where its changes can occur rapidly enough to be observed.

One such example is that of the peppered moth, which is outlined in Prosocial, by Paul Atkins, Steven Hayes, and David Sloan Wilson.

Before the industrial revolution, it was common for peppered moths to hide from birds of prey in lightly-coloured trees. However, after industrialisation got into full swing in 19th Century England, these trees now became covered in black soot.

Therefore, it became increasingly easy for birds of prey to spot lightly coloured moths in the trees, whereas darker-shaded moths could now blend in with the soot.

Since the colour of moths is a heritable trait which can be passed on from parents to offspring, the population gradually began to become dominated by darker moths, and lighter coloured moths were slowly ‘weeded out’ of the population.

The key thing to note here is that there was no ‘designer’ or planning involved at any stage of this process, but we did see the three key elements of natural selection at work.

First, the colour of the moths naturally varied between lighter and darker shades (variation).

Second, when the environment changed and trees became covered in soot, it gave the darker coloured moths a fitness advantage over lighter coloured moths (selection).

And third, darker coloured moths passed on their coloration genes to the next generation (retention).


Darwin’s Problem – How could Goodness Evolve in a ‘Dog-Eat-Dog’ World?

So far, an evolutionary perspective would seem to support the worldview that human nature is inherently selfish.

That is, individuals are in direct competition with others in their environment. Those that can compete effectively survive and pass their genes on to the next generation. Those that cannot, are gradually weeded out of the gene pool (like our brightly coloured moths).

Therefore, it stands to reason that we are descended from a long line of competitive, self-interested individuals.

Indeed, when Darwin first posited his theory of natural selection, he thought it could explain the design of all life forms on the planet (including human behaviour), without the need for a divine creator.

However, he quickly ran into a problem…

How could traits that we consider good, such as altruism, generosity, compassion, and honesty evolve?

If evolution is a game of ‘survival of the fittest’, in which natural selection rewards individuals who survive and reproduce better than competitors, and if goodness involves selfless acts (i.e., helping others to survive and reproduce – even at our own expense), then how could it evolve?

Surely individuals who embodied these traits would be much less likely to pass their genes on to future generations than those who focused on maximising their own self-interest?

That would in fact be true – if natural selection only occurred at the level of the individual.

However, what we haven’t considered yet, is that social behaviours always take place in the context of groups that are small compared to the total evolving population – whether it be a tribe of humans, a flock of birds, or a school of fish.

Therefore, any evolving population is not just a population of individuals competing with each other.

It is also a population of groups that compete with one another.

Now, if we apply Darwin’s theory of natural selection, it naturally follows that groups whose members cooperate more effectively with each other, will vastly outcompete groups with high levels of internal conflict.

Darwin himself posited this in The Descent of Man 150 years ago:

“There can be no doubt that a tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage and sympathy, were always ready to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection.”

Although Darwin’s group selection hypothesis was brilliant for his time, it was lacking scientific rigour and for many years fell out of favour within the scientific community.

However, recent years have seen a resurgence in ‘group selection’ thinking (in a new form) – thanks to the work of evolutionary biologist David Sloan Wilson and others in the field.

In his 2019 book: This View of Life, David put forward his theory of Multilevel Selection and explains how it can account for the evolution of altruism and cooperative behaviour in human life.

Let’s briefly look at the theory, how it differs from Darwin’s original hypothesis, and an example which illustrates how it works.


An Introduction to Multilevel Selection Theory

Photo by Anna Samoylova on Unsplash

“Selfishness beats altruism within groups. Altruistic groups beat selfish groups. Everything else is commentary”. E. O. Wilson & David Sloan Wilson

Multilevel selection theory (MLS) differs from Darwin’s original hypothesis in three important ways.

First, for traits that we consider good to evolve (e.g. altruism, honesty, etc), the selection pressure between groups must be stronger than the selection pressure within the group. In other words, you need competition between groups so that individuals within the group ‘band together’, and are properly incentivised to subordinate their own self-interest. Crucially, there is no guarantee that this will always be the case – and this means that in groups where within-group selection is the more powerful force, the traits we associate with goodness will not evolve. Therefore, there is always a kind of ‘tug-of-war’ going on between self-interest and the interest of the group.

The second key principle of MLS is that this tug-of-war takes place between multiple levels simultaneously. There is more to life than just individuals and the groups to which they belong. The natural world is better thought of like a multi-tiered hierarchy. In the human world, if you move down the hierarchy, we are each a group of cells that make up a multicellular organism. As we move up, these multicellular organisms exist within a social group such as a family. The family is part of a town, the town is part of a county, which is part of a province, which is part of a nation, etc. The ‘tug of war’ described above (between individual and group interest) exists at every level of the hierarchy.

The third key principle, then, is that selection at a lower level tends to undermine selection at next level up. In other words, what’s good for one of your cells might not be good for your whole body (e.g. cancer). What’s good for you (e.g. hoarding resources), might not be good for your tribe. What’s good for your tribe (e.g. deforestation for cattle grazing) might not be good for your ecosystem, and so on – all the way up to the welfare of the planet. Taking this principle into consideration, it follows that if you want selection at a higher level, mechanisms are required to curtail ‘selfish behaviour’ at lower levels.

A good example of group selection in action is how the human body has developed mechanisms for fighting off cancer. Biologically speaking, you are a community of approximately 37 trillion cells – all functioning harmoniously so you can read these words.

Your cells are constantly dividing, and every so often, mutations occur.

Mutations cause the ‘mutant’ cells to multiply at a faster rate than others, and as this continues, these groups of mutant cells form tumours. Then, by a process known as Metastasis, these mutant cells are dispersed to other areas of the body.

This is all ‘adaptive’ from the point of the individual cancerous cells as it helps them to survive and reproduce in the short term. However, over time, this process eventually leads to the death of the multicellular organism of which they are a part – which, in turn, means they will die too. But that doesn’t matter to them. Natural selection between individuals within the group is insensitive to the welfare of the group as a whole.

Evolution doesn’t have any foresight.

Luckily for us, the number of these mutations is tiny compared with the total number of cell divisions that take place within a multicellular organism like the human body, and for the most part, we are usually fairly good at fighting off cancer until we reach an old age.

Evolutionary scientists argue that this can be explained by the hundreds of millions of years of natural selection taking place at the level of multicellular organisms. In other words, organisms that were more resistant to cancer, survived and reproduced better than organisms that were less resistant to it.

Natural selection didn’t solve the problem of cancer within organisms, it did so by selection among organisms.


Human Groups as Multicellular Organisms

By this stage, you might be thinking – “Okay, I get it, but what has cancer got to do with our understanding of human nature?”

Well, just as our bodies have evolved mechanisms to suppress cancerous behaviour within their constituent parts so that the organism can flourish as a whole, some evolutionary biologists now think that selection at the level of human groups has led to the evolution of biological and behavioural mechanisms that prevent selfish behaviour within human groups, resulting in increased cooperation between group members – and this might explain how the traits we associate with goodness have evolved.

This idea is supported by the theory of ‘Major Evolutionary Transitions’, put forward by John Maynard Smith in 1998.

Smith posited that when between-group selection trumps within group selection, a group of individual replicators becomes a new, higher-level organism.

For example, individual genes cooperated to become genomes, different types of bacteria formed eukaryotic cells, and these cells cooperated to form multicellular organisms like the human body.

Although extremely rare in the natural world, major evolutionary transitions have been found to occur in a few instances such as in beehives and termite mounds.

So, is it possible that homo sapiens have undergone a major evolutionary transition in our distant past?

In other words, in the same way that the cells of the human body cooperated to become a new higher level multicellular organism, is it possible that our ancestors cooperated so effectively with each other, that their groups became adaptive units in their own right?

Let’s look at some evidence which suggests this might be the case.


1. The Cooperative Eye Hypothesis

Source: NBC News

Human beings are the only primate with ‘whites’ in our eyes.

This enables others to see where we are looking and to infer what our intentions might be.

From the perspective of one individual’s ability to compete with other members, this is a disadvantage.

To illustrate this, take the example of a group of chimpanzees moving through a jungle together. Now imagine one of them spots a banana tree. Because the rest of his eyes are a similar colour to his pupils, his fellow chimps have no idea what he’s seen. This provides a fitness advantage to him, because he can come back later and feast on the bananas by himself – giving him more energy than his rivals.

Humans, on the other hand, don’t have this luxury. If, in the same situation, we spot a banana tree, the whites in our eyes allow other members of our group to see what we’ve seen, which means they get a share of the action too.

The cooperative eye hypothesis suggests that we have ‘whites’ in our eyes because they provided an adaptive advantage at the group level. Groups of humans with this trait would share more and cooperate more effectively than groups without it – and therefore outcompete them.

2. Shared intentionality

Source: Ayelt van Veen on Unsplash

‘It is inconceivable that you would ever see two chimpanzees carrying a log together.’ – Michael Tomasello

The “Shared Intentionality Hypothesis” put forward by Michael Tomasello, argues that one of the key things that differentiates us from other primates and explains our rapid rise to the top of the food chain is our ability to share intentions with each other.

To test this, Tomasello set up experiments which compared intelligence levels between two-year old human children and adult great apes (chimpanzees and orangutans).

The first half of the tasks involved physical problem-solving tasks, such as using a tool to get food through a cage.

The second half added a social element which required understanding the intentions of the experimenter. For example, the experimenter would point to a cup containing food, and then the participant (monkey or human) would have to use the signal to infer where the food was.

In the physical tasks, human infants and monkeys scored almost evenly.

However, in the tasks which involved a social signal like pointing, human children vastly outperformed the apes.

This, along with other results from the study, provides evidence in favour of group selection.

Groups containing members who could share intentions with each other quickly and easily (through behaviours like pointing), would be at a considerable advantage over groups whose members could not.

3. Morals – The Original Police Force

Before reading on, take a second to think about all of the traits you associate with goodness in a person.

It might even help to picture a particular individual – real or fictional.

Got some?

Okay, now think about all of the characteristics of someone who you consider evil.

When giving public lectures to a wide variety of audiences all over the world, David Sloan Wilson asks his audience this question, and almost invariably gets the same answers.

Traits that we associate with good are usually linked with selfless and altruistic behaviour, such as; generous, caring, honest, helpful, productive, etc.

Traits that we associate with evil are typically related to selfishness in some form or another, e.g., greedy, lazy, dishonest, cruel.

Why might this be?

In ‘The Righteous Mind’, Jonathan Haidt argues that when we first came together and started cooperating in larger groups, we needed a way to regulate individual self-interest within the group, so that the group could function harmoniously as a whole.

One of the ways we did this was through the development of a strong sense of morality.

Haidt argues that it’s no coincidence that the traits we evolved to look upon favourably involve prosocial acts that would benefit the group as a whole, whereas the traits we associate with evil would typically benefit an individual at the expense of the group.

Thus, in our distant past, our moral intuitions about behaviours acted like an ‘internal police force’ that helped to regulate the behaviour of individual group members.

From a group selection point of view, it’s easy to see how groups with a strong sense of morality would have greater cohesion and cooperation, and therefore outcompete those without it. For one, moral groups would be much less likely to have ‘free riders’ – individuals who let others do the work, while still reaping the rewards.

4. Gossip

Source: Ashkan Forouzani on Unsplash

Robin Dunbar’s “Gossip and Grooming Hypothesis” suggests that gossip played a vital role in increasing the size of the human brain and the size of the groups we could maintain.

Before gossip, our only way to maintain social bonds was by ‘grooming’ – a social process by which primates touch and stroke each other’s bodies and remove unwanted parasites.

Hence the phrase: “You scratch my back and I’ll scratch yours”.

Dunbar argues that grooming alone placed an upper limit on human group sizes because it can only take place between two individuals, and typically takes a long time. (Some primates groom for up to one fifth of their day.)

However, after the advent of gossip, we could now maintain social bonds with significantly larger numbers of people through the mechanism of idle chit chat. We no longer needed to spend hours with just one person, and could now effortlessly share information with (and about) each other – allowing us to keep tabs on the behaviour of other members of our groups.

In ‘Evolution for Everyone’, David Sloan Wilson argues that gossip acts like a behavioural ‘immune system’ helping us to regulate the behaviour of individuals within groups.

To illustrate this, think of the advantage that an early human tribe whose members gossiped had over one that didn’t.

In a tribe where gossip is non-existent, it’s a lot easier for me to get away with self-interested behaviours that benefit me, but harm the group as a whole. For example, taking more than my fair share of food, stealing, bullying, etc. If another group member sees me do any of these things, he might not trust me anymore, but my survival chances wouldn’t be that badly affected.

However, if I live in a tribe that can gossip, and if even just one person sees me do one of these things, then my reputation is ruined. The information will rapidly spread to other members via the mechanism of gossip. I’d now be less likely to find a mate, and may even be expelled from the tribe altogether.

This might explain why gossip tends to focus on the ‘bad’ behaviours of others and equally our fascination with soap operas, conflict and celebrity scandals in the modern world.

5. Stoning for Equality

Source – Benjamin Davies on Unsplash

Although we share the same common ancestor, anthropologists have found significant differences between the organisation of chimpanzee communities and early tribes of hunter gatherers.

Chimpanzee communities tend to be hierarchical, with alpha males asserting dominance over other members and subordinates avoiding the wrath of superiors through submissive signalling.

In contrast, many anthropologists posit that early human tribes were, for the most part, egalitarian, and that unequal societies only arose when we began to organise in larger numbers after the advent of agriculture.

What might explain this?

One hypothesis comes from molecular biologist Paul Bingham, who argues that it was our ability to throw stones that led to more equal groups. (Human throwing capabilities are vastly superior to any other primate.)

Although stone throwing was initially used to defend against predators and kill prey animals, Bingham’s hypothesis is that we adopted this skill to regulate the behaviour of our groups.

To illustrate this, take the example of an early tribe in which one member was much physically larger, stronger and more intimidating than other members – traits he used to bully, threaten and take more than his fair share of resources.

Before the innovation of stoning, the other members would have no choice but to submit to this tyrannical character or pay the consequences.

However, after we could stone each other, it levelled the playing field.

Now, all the other members had to do was band together, surround this individual and take him down with an array of stones to the skull.

It’s easy to see how the fear of being stoned to death would be a significant deterrent against tyrannical alpha behaviour, and thus lead to more egalitarian and cooperative groups. Therefore, groups that could stone were not only better equipped to defend against predators and hunt prey animals, they were also likely to be more effective co-operators, giving them a selective advantage over groups without this ability.

6. The Psychology of Sacredness

Almost every human culture has a religious or spiritual tradition embedded within it.

Although new atheists such as Richard Dawkins argue that religions are simply ‘parasitic memes’, that use individuals for their own replication and provide no benefit to society as a whole, there are a growing number of evolutionary theorists making the case that these traditions may have been crucial for creating moral communities in our distant past.

Proponents of this view argue that groups who were able to come together under shared belief systems had an adaptive advantage over those who couldn’t.

There are two possible explanations for this.

First, these traditions typically involve rituals where individuals come together regularly as a community, engage in spiritual practices and connect with some kind of higher power. Frequently meeting like this would not only increase loyalty and kinship with other members, it would also create a stronger group identity.

Second, religions often come with a moral code that acts as a strong incentive for “good” behaviour (that benefits the group) and a deterrent for “bad” behaviour (that benefits the individual but harms the group).

Thus, religious groups would invariably have more prosocial members and greater cooperation than non-religious ones – and would therefore outcompete them.


Conclusion

So, coming back to our original question:

Is human nature fundamentally self-interested or co-operative?

The answer to this hinges on one key variable:

Did human groups undergo a ‘major evolutionary transition’ in our distant past, so that they could function as adaptive units (like multicellular organisms) in their own right?

The evidence reviewed in this post suggests this might be the case.

However, just because human groups can function as adaptive units, does not guarantee that we will do so.

Multilevel selection theory tell us that there is always a kind of ‘tug of war’ going on between selection at the individual level, and selection at the group level.

If within group selection is the stronger force, our competitive and self interested nature comes to the surface. Conversely, if group selection is the more powerful of the two, then it tends to bring out the inner co-operator in all of us.

Or, as David Sloan Wilson and Edward O. Wilson put it in their 2007 paper:

“Selfishness beats altruism within groups. Altruistic groups beat selfish groups. Everything else is commentary.”

As we move forward into an uncertain future, it is vital that governments, policy makers and leaders in our society take this into account, and aim to create cultural contexts that foster our innate capacity for cooperation, rather than appealing to our inner drives towards competition and individual self interest.

The work of David Sloan Wilson – This View of Life and Prosocial in particular, offers a great introductory guide for anyone interested in how we can best do this.


Further Reading and Resources

Please click here for a ‘mini-lecture’ which summarises the key ideas from this post.

Books:

The Major Transitions in Evolution – John Maynard Smith

Prosocial – Paul Atkins, Steve Hayes & David Sloan Wilson

This View of Life – David Sloan Wilson

The Righteous Mind – Jonathan Haidt

Death from a Distance – Paul Bingham & Joanne Souza

The Descent of Man – Charles Darwin

On the Origin of Species – Charles Darwin

Darwin’s Dangerous Idea – Daniel Dennett

Papers:

Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis

The ‘Perception Matters’ Common Cause UK Value Survey

Major Transitions in Individuality

Contrasting the Social Cognition of Humans and Nonhuman Apes: The Shared Intentionality Hypothesis

Beyond Beliefs: Religions Bind Individuals Into Moral Communities

Rethinking the Theoretical Foundation of Sociobiology

Links:

Jonathan Haidt Lecture: “How Human Beings Got Morality, Religion, Civilization, and Humanity”

BBC – Where Did Gossiping Come From?

Early men and women were equal, say scientists