Religion may be a survival mechanism. Ian Semple investigates whether we are born to believe.
First, some figures. Last year a poll found that 85 per cent of Americans believe God created the universe. In Nigeria, 98 per cent claimed always to have believed in God, while nine out of 10 Indonesians said they would die for their God or religious beliefs, says the ICM Research survey, which questioned 10,000 people.
In Ireland, 87 per cent of the population believe in God, a survey by the Market Research Bureau of Ireland found in January. Rather than rocking their faith, 19 per cent said tragedies such as the Asian tsunami, which killed 300,000 people, bolstered their belief. Polls have their faults, but if the figures are even remotely right they show the prevalence of faith in the modern world.
Faith has long been a puzzle for science, and it's no surprise why. By definition, faith demands belief without a need for supporting evidence, a concept that could not be more opposed to the principles of scientific inquiry.
So why do so many people believe? And why has belief proved so resilient as scientific progress unravels the mysteries of plagues, floods, earthquakes and our understanding of the universe? By injecting nuns with radioactive chemicals, by scanning the brains of people with epilepsy and studying naughty children, scientists are working out why. When the evidence is pieced together, it seems that evolution prepared what society later moulded: a brain to believe.
One factor in the development of religious belief was the rapid expansion of our brains as we emerged as a species, says Todd Murphy, a behavioural neuroscientist at Laurentian University in Canada. As the frontal and temporal lobes grew larger, our ability to extrapolate into the future and form memories developed. "When this happened, we acquired some very new and dramatic cognitive skills. For example, we could see a dead body and see ourselves in that position one day. We could think, 'that's going to be me'."
That awareness of impending death prompted questions: why are we here? What happens when we die?
In developing societies, religious beliefs also encouraged bonding within groups, which in turn bolstered the group's chances of survival, says Pascal Boyer, an anthropologist-turned-psychologist at Washington University in St Louis, Missouri.
Some believe religion was so successful in improving group survival that a tendency to believe was "positively selected" for our evolutionary history. Others maintain religious belief is too modern to have made any difference.
"What I find more plausible is that rather than religion itself offering any advantage in evolutionary terms it's a byproduct of other cognitive capacities we evolved, which did have advantages," Boyer says.
Psychological tests Boyer has run on children go some way to proving our natural tendency to believe. "If you look at three- to five-year-olds, when they do something naughty, they have an intuition that everyone knows they've been naughty, regardless of whether they have seen or heard what they've done. It's a false belief, but it's good preparation for belief in an entity that is moral and knows everything," he says.
Childish belief is one thing, but religious belief is embraced by people of all ages and is by no means the preserve of the uneducated. Boyer says the persistence of belief into adulthood is at least partly due to a presumption. "When you're in a belief system, it's not that you stop asking questions, it's that they become irrelevant," he says. "Why don't you ask yourself about the existence of gravity? It's because a lot of the stuff you do every day presupposes it and it seems to work, so where's the motivation to question it?"
While some continue to tease out the reasons for the emergence of religion and its persistent appeal, others are delving into the neuroscience of belief in the hope of finding a biological basis for religious experience. As a starting point, many studies focused on people with particular neural conditions that made them prone to experiences so intense they considered them to be visions of God.
At the University of California in San Diego, the neuroscientist V.S. Ramachandran noticed that a disproportionate number of patients - about a quarter - with a condition called temporal lobe epilepsy reported having deeply moving religious experiences. "They'd tell me they felt a presence or suddenly felt they got the meaning of the whole cosmos. And these could be life-changing experiences," Ramachandran says. The feelings always came during seizures, even if the seizures were so mild they could only be detected by sensitive electroencephalograms (EEGs). Between seizures, some patients became preoccupied with thoughts about God.
Ramachandran developed three explanations he thought might explain why the patients with epilepsy seemed so spiritual: He considered that the upwelling of emotion caused by the seizure might simply overwhelm, and patients made sense of it by believing that something extremely spiritual was going on. The seizure might prompt the left hemisphere of the brain to make up stories to account for seemingly inexplicable emotions. The ability of the left hemisphere to "confabulate" like this is well known to neuroscientists. He wondered whether seizures disrupted the function of part of the brain called the amygdala which, among other tasks, helps us focus on what is significant while allowing us to ignore the trivial.
Ramachandran tested a couple of patients using what is called galvanic skin response. Two electrodes are used to measure tiny changes in the skin's electrical conductivity, an indirect measure of sweating. In most people, conductivity goes up when they are shown violent or sexual pictures, or similarly loaded words.
In the test, Ramachandran found that patients with temporal lobe epilepsy responded very differently from others. Violent words such as "beat" and sexual words produced no reaction, but religious icons and the word "God" evoked a big response.
With only two patients involved in the study, Ramachandran says it is impossible to draw any conclusions, but if the results stand up to future testing, it might indicate that seizures in the temporal lobe strengthen certain neural pathways connected to the amygdala, meaning we attribute significance to banal objects and occurrences. "If those pathways all strengthen indiscriminately, everything and anything acquires a deep significance, and when that happens, it starts resembling a religious experience. And if we can selectively enhance religious sentiments, then that seems to imply there is neural circuitry whose activity is conducive to religious belief. It's not that we have some God module in our brains, but we may have specialised circuits for belief."
At the University of Pennsylvania, Andrew Newberg, a radiologist, has cast a wider net to scan the brains of people performing spiritual activities. By injecting radioactive tracers into the veins of nuns, Buddhists and others, he has constructed brain maps that show how different practices affect neural processing.
"What comes out is there's a complex network in the brain and, depending on what you do, it is activated in different ways," Newberg says. "If someone does Tibetan Buddhist mediation they'll activate certain parts of their brain, but if you have a nun praying they'll activate slightly different parts, with someone doing transcendental meditation activating other areas again."
Newberg uncovered the neural processing behind the religious experience of "oneness" with the universe. Blood flow drops off in the parietal lobe, a brain structure that helps us orient ourselves by giving us a sense of ourselves. "What seems to be happening is that as you block sensory information getting into the parietal lobe, it keeps trying to give you a sense of self, but it no longer has the information to do so. If that happens completely, you might get this absolute feeling of oneness."
Newberg has been criticised for his investigations into the essence of spiritual experience, with the most vehement attacks coming from atheists. "Some people want me to say whether God is there or not, but these experiments can't answer that. If I scan a nun and she has the experience of being in the presence of God, I can tell you what's going on in her brain, but I can't tell you whether or not God is there," he says. Religious groups point out that there is more to religion than extreme experiences. It is a criticism Newberg acknowledges. "The problem is, the people who have these experiences are so much easier to study."
As neuroscientists unpick the biological mechanisms behind religious experience, others are considering what to do with the information. At Laurentian University, Todd Murphy and a colleague, Michael Persinger, are developing devices they think can stimulate parts of the brain to enhance spiritual experiences. Others see the possibility for drugs designed to boost spirituality. Newberg says this would be underpinning a practice that has existed for hundreds of years. "If you talk to a shaman who takes a substance so they can enter into the spirit world, they don't think that diminishes the experience in any way," he says.
Many scientists, while stressing that they have set out to explore religion rather than disprove its basis, say that no matter what they uncover about the nature of spiritual experiences, mass religious belief will continue. The fastest-growing religions in the US are the Mormon church and Scientology, both popular, Boyer says, largely because they are new. In other parts of the world, more fundamentalist religions succeed because they give a clear vision of the world.
"For two centuries, there's been competition between churches and in the free market of religion the products get better and better as people want different things," Boyer says. "Will science be the death of religion? As neuroscience, it's interesting to see how brains can create very strange states of consciousness, but in terms of threatening religion, I think it'll have absolutely no effect."
Religion may be a survival mechanism. Ian Semple investigates whether we are born to believe.