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How evolution found God

• 28 January 2006 by Robin Dunbar

RELIGIOUS belief is a conundrum. In our everyday lives, most of us make at least some effort to check the truth of claims for ourselves. Yet when it comes to religion, studies show that we are most persuaded by stories that contradict the known laws of physics. Tales of supernatural beings walking on water, raising the dead, passing through walls, foretelling the future, and the like, are universally popular. At the same time, however, we expect our gods to have normal human feelings and emotions. We like our miracles, and those who perform them, to have just the right mix of otherworldliness and everyday characteristics.

Why are we humans so willing to commit to religious beliefs we can never hope to verify?

You might well think that question falls outside the realm of scientific investigation. Evolutionary biologists in particular have taken their cue from their own guru, Charles Darwin, and studiously ignored the whole issue of god. But now that is starting to change. It's not clear what has triggered the interest, but a significant factor has probably been the growing recognition that religion is a real evolutionary puzzle. On the face of it, religious behaviour seems to be at odds with everything we biologists hold dear. The reductionist view sees us as merely vehicles for our selfish genes - yet religions embrace charity to strangers, submission to the will of the community, and even martyrdom. No self-respecting baboon or chimpanzee would ever willingly kowtow to the good, the bad or the ugly in quite the same way humans do.

Perhaps the biggest stumbling block for evolutionary biologists has been recognising that religion might have a functional advantage. If a biological trait has evolved, we want to know what use it is - and by that we mean how does possessing this trait make an individual better adapted to survive and pass their genes on to the next generation. That's not always apparent where religion is concerned. But in recent years,

evolutionary biologists including myself have come to realise that there are some important aspects of religion that do seem to have benefits.

Being part of a group massively ratchets up your endorphin rush

Evolutionary biologists have identified at least four ways in which religion might be of benefit in terms of evolutionary fitness.

1. The first is to give sufficient explanatory structure to the universe to allow us to control it, perhaps through the intercession of a spirit world.
   
2. The second is to make us feel better about life, or at least resigned to its worst vagaries - Marx's "opium of the masses".
   
3. A third is that religions provide and enforce some kind of moral code, so keeping social order.
   
4. Finally, religious belief might bring a sense of communality, of group membership.

The first is to give sufficient explanatory structure to the universe to allow us to control it, perhaps through the intercession of a spirit world.

The first idea - religion as cosmic controller - seems highly plausible, given that many religious practices aim to cure diseases and foretell or influence the future. It was the view favoured by Freud. However, since religious belief does not necessarily enable us to control the vagaries of the world, I find it difficult to see this as the evolutionary force behind the origin of religion. Rather, I suspect that this benefit came about as a by-product once our ancestors had evolved religion for one of the other reasons - and thus had a big enough brain to figure out some metaphysical theories about the world.

The second is to make us feel better about life, or at least resigned to its worst vagaries - Marx's "opium of the masses".

The second hypothesis, Marx's opium, seems more promising. In fact, it turns out that religion really does make you feel better. Recent sociological studies have shown that compared with non-religious people, the actively religious are happier, live longer, suffer fewer physical and mental illnesses, and recover faster from medical interventions such as surgery. All this is bad news for those of us who are not religious, but it might at least prompt us to ask why and how religion imparts its feel-good factor. And we'll come back to that later.

3) A third is that religions provide and enforce some kind of moral code, so keeping social order.

4) Finally, religious belief might bring a sense of communality, of group membership.

The other two options are concerned with individuals benefiting from being part of a cohesive, supportive group. Moral codes play an obvious role in ensuring that group members keep singing from the same hymn sheet. Nevertheless, the sort of formalised moral codes preached and enforced by today's major religions are unlikely to provide much insight into the beginnings of religious belief. They are associated with the rise of the so-called world religions with their bureaucratic structures and the alliance between church and state. Most people who study religion believe that the earliest religions were more like the shamanic religions found in traditional small-scale societies. These are quite individualistic, even though some individuals - shamans, medicine men, wise women, and the like - are acknowledged as having special powers. Shamanic religions are religions of emotion not intellect, with the emphasis on religious experience rather than the imposition of codes of behaviour.

Social glue

In my view, the real benefits of religion in terms of evolutionary fitness have to do with the fourth hypothesis. The idea that religion acts as a kind of glue that holds society together was also favoured by Emil Durkheim, one of the founding fathers of modern sociology. Now, though, we know more about how this works.

Religions bond societies because they exploit a whole suite of rituals that are extremely good at triggering the release of endorphins, natural opioids in the brain. Endorphins are part of the body's pain-control system, a slow-acting mechanism that takes over when the various neurological systems of pain control have peaked in their effectiveness. Endorphins come into their own when pain is modest but persistent - then they flood the brain, creating a mild "high". Perhaps that is why religious people often seem so happy. What's more, and here's the rub, endorphins also "tune up" the immune system, which probably explains why religious people are healthier.

This may be why religious rituals so often involve activities that are physically stressful - singing, dancing, repetitive swaying or bobbing movements, awkward postures like kneeling or the lotus position, counting beads, and occasionally even seriously painful activities like self-flagellation. Of course, religion is not the only way to get an endorphin fix. You will also get a high from jogging, swimming or pumping iron, but religion offers something more. When you experience an endorphin rush as part of a group, its effect is ratcheted up massively. In particular, it makes you feel very positive towards other group members. It creates a sense of brotherhood and communality.

Monkey morality

While this may explain the immediate advantage of religion, it raises the question of why we need it at all. The answer, I believe, goes back to the very nature of primate sociality. Monkeys and apes live in an intensely social world in which group-level benefits are achieved through cooperation. In effect, primate social groups, unlike those of almost all other species, are built on implicit social contracts: individuals are obliged to accept that they must forgo some of their more immediate personal demands in the interests of keeping the group together. If you push your personal demands too far, you end up driving everyone else away, and so lose the benefits that the group provides in terms of protection against predators, defence of resources and so on.

The real problem that all such social contract systems face is the "free-rider" - someone who takes the benefits of sociality without paying their share of the costs. Primates need a powerful mechanism to counteract the natural tendency for individuals to free-ride whenever they are given the chance. Monkeys and apes do this through social grooming, an activity that creates trust, which in turn provides the basis for coalitions. Exactly how this works is not yet clear, but what we do know is that endorphins are a vital ingredient. Grooming and being groomed lead to the release of endorphins. Endorphins make individuals feel good, providing an immediate motivation to engage in the activity that bonds the group.

The trouble with grooming as far as our own species is concerned, however, is that it is a one-on-one activity, so it's very time-consuming. At some stage in our evolutionary past, our ancestors began living in groups that were too large for social grooming to provide effective glue. Such large groups would also have been especially prone to exploitation by free-riders. They needed to come up with an alternative method of group bonding. In the past, I have suggested that gossip would have played a role, allowing individuals to perform an activity that provides a similar function to grooming but in small groups rather than one to one. But religion would have taken this a step further, allowing larger groups to bond.

It is important to emphasise, however, that if this account of the origins of religion is right, then it began very much as a small scale phenomenon. Perhaps early religious practices included something like the trance dances found in shamanistic-type religions today. The !Kung San of southern Africa, for example, seek to heal rifts in personal relationships within the community by using music and repetitive dance movement to trigger trances. It is easy to see how this sort of activity could have been beneficial to our ancestors, uniting the group, discouraging free-riders, and so increasing the chances that individuals would survive and reproduce.

However, there is one last issue. Religion is not just about ritual, it also has an important cognitive component - its theology. The endorphin-based group-bonding effects of the rituals only work if everyone does them together. Which is where the theology comes in - it provides the stick and the carrot that make us all turn up regularly. But to create a theology our ancestors needed to evolve cognitive abilities that far exceed those found in any other animal species (see "The origins of religion"). It is these psychological mechanisms that have been exploited down the ages by political elites in various attempts to subjugate the rest of the community. Marx, it seems, was right after all.

The origins of religion

Our ancestors did not always have religion, yet many religious practices seem to have very ancient origins. So when did religion first evolve? Archaeologists have long been fascinated by this question. One indication is burial. Some experts believe this began as far back as 200,000 years ago with the Neanderthals, but the motivation for such cacheing of bodies is ambiguous. So most archaeologists more cautiously define the appearance of religion by looking for evidence of grave goods in burials, since these at least unequivocally imply belief in an afterlife. Deliberate burials of this kind do not occur much before 25,000 years ago. Such burials imply a sophisticated theology, so we can safely assume that these were preceded by a long phase of less sophisticated religious belief. But without evidence on the ground, can we see any further back than this?

I have suggested that there is another way to get an unexpected insight into the question. It comes from asking what kind of mind is required to hold religious beliefs. Take the statement: "I believe that god wants..." To grasp this an individual needs theory of mind - the capacity to understand that another individual (in this case, god) has a mind of his own. Philosophers call this "second-order intentionality" because such statements contain two notions of intent: I believe and god wants. But we need more than this to build a religion.

Third-order intentionality allows me to state: I believe that god wants us to act with righteous intent. At this level, I have personal religion. But if I am to persuade you to join me in this view, I have to add your mind state: I want you to believe that god wants us to act righteously. That's fourth-order intentionality, and it gives us social religion. Even now, you can accept the truth of my statement and still it commits you to nothing. But add a fifth level (I want you to know that we both believe that god wants us to act righteously) and now, if you accept the validity of my claim, you also implicitly accept that you believe it too. Now we have what I call communal religion: together, we can invoke a spiritual force that obliges, perhaps even forces, us to behave in a certain way.

So, communal religion requires fifth-order intentionality, and this also happens to be the limit of most people's capacity as indicated by research done by myself and my colleagues. I think this is no coincidence. The majority of human activities can probably be dealt with using second or third-order intentionality. The two extra layers beyond this undoubtedly come at some considerable neural expense. Since evolution is frugal, there must be some good reason why we have them. The only plausible answer, so far as I can see, is religion. And that's where this line of reasoning can throw light on the origins of religious belief.

As far as we know, all other animals are locked into first-order intentionality, with the exception of great apes who are just about able to cope with second order. If you look at the brains of humans and other animals you find that the level of intentionality they can achieve scales linearly with the volume of grey matter in their frontal lobes (a particularly important part of the brain's processing units). This can be used to work out the level of intentionality our extinct ancestors were capable of - provided you have a fossil skull from which you can measure the overall volume of the brain.

Plotting these values onto a graph, the evidence suggests that as early as 2 million years ago, Homo erectus would have aspired to third-order intentionality, perhaps allowing them to have personal beliefs about the world. Fourth-order intentionality - equating to social religion - appeared with archaic humans around 500,000 years ago. And fifth order didn't appear much before the evolution of anatomically modern humans around 200,000 years ago - early enough to ensure that all living humans share this trait, but late enough to suggest that it was probably a unique adaptation.

In a separate strand of research, my colleagues and I have also found a relationship between the size of the brain's neocortex and social group size in primates. Interestingly, this "social brain hypothesis" predicts that around the time our ancestors evolved the capacity for fifth-order intentionality their community sizes would have exceeded about 120 individuals. Religion may have evolved to provide the mechanism for bonding them into a coherent social unit.

Robin Dunbar is professor of evolutionary psychology at the University of Liverpool, UK, and co-director of the British Academy's Centenary Research Project "Lucy to language: the archaeology of the social brain". His most recent book, The Human Story, is published by Faber and Faber