Brain Buys (29 page)

Theories on the biological origins of supernatural beliefs and religion tend to focus on
Homo sapiens
that have been around for fewer than 200,000 years. But what of the millions of years of hominin evolution before
Homo sapiens
? We do not know if
Homo erectus
had supernatural beliefs, but he likely pondered something as he lay beneath the stars. Did he ponder who put them there or how to build a better knife? Would it not be useful to prioritize these thoughts? A set of genes that encouraged compartmentalization of problems into tangible and intangible categories may have been adaptive.

The obvious counterargument to this hypothesis is that today, supernatural and religious beliefs can be maladaptive—the evolutionary equivalent of firefighters starting a controlled burn to remove the underbrush and accidentally burning down the city. If at first we attributed disease and natural disasters to supernatural phenomena beyond our control, we next put these phenomena under the control of supernatural beings, and, finally, in a desperate effort to control the uncontrollable, we started negotiating with the deities we created. Today, we partake in intricate rituals, offer sacrifices, and build elaborate monuments to honor our capricious gods. Worse, as illustrated by the story of Robyn Twitchell, supernatural beliefs can be maladaptive because they impede the acceptance of scientific and life-saving knowledge.

But any theory of the biological origins of supernatural and religious beliefs must confront the current maladaptive consequences of these beliefs. Like so many other aspects of human behavior it does not make sense to try to understand the evolution of religion by trying to explain what it encompasses today. Even something as obviously adaptive as sexual desire is to an extent maladaptive today. Many of our personal efforts and struggles, as well as significant chunks of the marketing and fashion industries (not to mention the pornography industry), are driven by sexual desire, even though with the advent of contraceptive methods humans have managed to decouple sex from its ultimate biological goal of reproduction.

GODS IN THE BRAIN

Science, strictly speaking, cannot prove that gods do not exist, but it can reject the hypothesis because as the author Christopher Hitchens reminds us “what can be asserted without evidence can also be dismissed without evidence.”
²⁴
Science can state with the same degree of confidence that gods do not exist, as it can state that we do not all live in pods and are jacked-in to a shared virtual world, as in the movie
The Matrix
. (Actually, it is much more unlikely that we all live in the Matrix because that scenario is at least compatible with all known laws of physics and biology.) Science does not claim to reveal absolute truths, but rather it settles on scientific facts based on an accumulated body of knowledge, and experimentation aimed both at validating
and
disproving those facts. If new evidence comes to light, science will reevaluate its position that gods do not exist. Until then, science should not ask whether gods exist, but why they exist in our brains.

The first challenge in studying the neural basis of religious beliefs is to find some formal measure of exactly what it means to be religious. Some people who are not part of any organized religion are nevertheless very spiritual—they firmly believe in supernatural entities—and some who go to church every Sunday are not particularly religious. The most used measure of spirituality is part of a personality test called the Temperament and Character Inventory. The test consists of over 200 questions, including “Sometimes I have felt my life being guided by a spiritual force greater than any human being” and “I sometimes feel a spiritual connection to other people that I cannot explain in words.” Together, a subset of the questions aims to capture a personality trait referred to as
self-transcendence
.

Using this measure as a proxy for spirituality, a number of researchers have sought the neural footprints of supernatural and religious beliefs. For example, one study examined the relationship between self-transcendence scores and the amounts of a specific receptor of the neurotransmitter serotonin in the brain.
²⁵
Serotonin receptors are the target of some hallucinogenic drugs, including LSD, and the serotonin pathways are the target of some antidepressants drugs, including Prozac and Paxil. Although serotonin plays an important role in many aspects of brain function, including mood, appetite, sleep, and memory, basic questions remain a mystery. Indeed, it is not necessarily even the case that having less of some types of serotonin receptors translates into less serotonin activity in the brain, because some receptors can inhibit further release of serotonin. Using a brain imaging technique that allows investigators to measure the amount of serotonin receptors using a short-lasting radioactive compound, the authors found that subjects with relatively few serotonin receptors tended to have a high self-transcendence rating, whereas those with more receptors had a low score. The authors concluded that “the serotonin system may serve as a biological basis for spiritual experiences.” Such conclusions, however, are overly simplistic, and among other things suffer from the common confound of correlations being taken as evidence of causation. (The seductive power of correlations is a brain bug that plagues the general public and scientists alike.) Neurotransmitters in the brain generally do not operate independently of each other, so the levels of serotonin receptors may themselves be correlated with the levels of many different neurotransmitters and receptors; any one of which, or the combination of all, could contribute to spirituality. Or, the self-transcendence trait could be correlated with innumerous other personality traits, such as happiness or socioeconomic group, that might alter levels of serotonin receptors.

In the nineteenth century phrenologists claimed that there was an organ of spirituality in the brain, and that an indentation or bump in the middle of the head, just below the crest of the skull, was an indication of spirituality. Today the search for a specific part of the brain that drives spirituality continues—albeit with somewhat more sophisticated approaches. Some studies have reported that temporal-lobe-epilepsy patients often experience flashes of spirituality, leading to the suggestion that there is a “God center” somewhere in the temporal lobe.
²⁶
In other well-publicized studies scientists used transcranial magnetic stimulation to activate parts of the brain, and reported that stimulation of the right hemisphere increases the likelihood subjects will describe experiencing a spiritlike “sensed presence.” These results were controversial, and it has been suggested that they may be an experimental artifact caused by suggestibility.
²⁷
Such reports are further complicated by the fact that religious experiences or a “sensed presence” are subjective at best, and highly influenced by cultural factors, context, and the many priming effects we have examined in previous chapters.

Other studies have relied on brain lesions to gain insights into the neural basis of religiosity. One such study asked if people’s spiritual outlook changed after part of their brain was surgically removed as part of their brain cancer treatment. Here the Temperament and Character Inventory was used to gauge people’s supernatural and religious views before and after their surgery. Given the gravity of brain cancer and surgery, it would, of course, not be at all surprising if people’s views on supernatural matters, particularly those regarding religion and an after-life, changed (perhaps patients relied more or less on spiritual support depending on the outcome of the surgery). Importantly the investigators controlled for this by separating the subjects into groups that had to have the anterior or posterior parts of the parietal cortex (the area behind the frontal lobe) removed. On average the self-transcendence scores of patients who had the posterior part of the parietal cortex (right, left, or both hemispheres) increased after the surgery; no significant change was observed in the scores of the patients who had an anterior portion of the parietal cortex removed. Notably none of the other character traits of the Temperament and Character Inventory, which include measures of novelty-seeking and self-control, were significantly different before and after the surgery—a finding consistent with the notion that many aspects of cognition are distributed throughout many areas of the brain and thus resistant to localized lesions (what was referred to as graceful degradation in Chapter 3.

This study would seem to suggest that the posterior parietal cortex is partly responsible for dampening people’s supernatural beliefs. However, other interpretations are possible. For example, this general area of the brain has also been implicated in our sense of body awareness, and, since spirituality might be related to an ability to see oneself outside the body (“out-of-body experiences”), the authors point out that the results may be related to an altered sense of personal and extrapersonal space.
²⁸
Regardless of the ultimate explanation of the results, however, the study does suggest that spirituality is a trait that is not necessarily inseparable from other dimensions of our personalities.

Many, probably most, neuroscientists do not expect to find a single “belief center” in the brain, any more than they expect to find a single area responsible for love or intelligence. Together the cumulative evidence to date suggests that religious beliefs likely engage a distributed network of different brain areas functioning as a committee. For example, a brain-imaging study led by the neuroscientist and author Sam Harris examined patterns of brain activation in response to religious and nonreligious statements, such as “Jesus was literally born of a virgin” and “Childbirth can be a painful experience.” The study revealed that the two types of questions produced different patterns of activity across a broad network of areas throughout the brain and the patterns were similar independent of whether the subjects were believers or nonbelievers.
²⁹

It is much too early to make any conclusive statements regarding the neural basis of supernatural and religious beliefs, but it seems clear that as with most complex personality traits there will not be a single “God center,” “God gene,” or “God neurotransmitter.” Furthermore, if there is a genetic basis to our supernatural beliefs it is possible we are asking the wrong question altogether. It may be best not to ask if supernatural beliefs were programmed into the human brain, but to assume that they are the brain’s default state and that recent evolutionary pressures opened the door for nonsupernatural, that is, natural, explanations for the questions that in the past eluded our grasp. As mentioned above, the studies of Jesse Bering and others suggest that children naturally assume the existence of a manifestation that outlasts the physical body. It is indeed hard to see how children, as well as early humans, could be anything but innate dualists in the face of vast ignorance about natural laws. Additionally, the observation that surgical removal of part of the brain increases spirituality suggests that supernatural beliefs may be the default state, and that we evolved mechanisms capable of suppressing these beliefs.

Where did life come from? Replying that a god, whether Zeus, Vishnu, or the Invisible Pink Unicorn, created life is more intuitively appealing than stating that life is the product of complex biochemical reactions sculpted by natural selection over billions of years. It seems downright logical that something as complex as life would require planning on someone’s part. The brain bug is in the fact that for some reason, when told that a god created life, we do not reflexively ask, “But wait a minute, who created God?” The brain seems to naturally accept that an agent is an acceptable explanation, no more needs to be said. This fallacy is almost associative in nature; the words
create
and
make
and their proxies carry with them implicit associations about agency and intention.

If dualism is our default state perhaps we should not think of how supernatural beliefs evolved, but how we came to seek and accept natural and science-based answers to the mysteries of “life, the universe, and everything.” If other animals can be said to think at all, presumably their worldview more closely resembles our own supernatural beliefs, that is, most things are indeed indistinguishable from magic. What probably distinguishes the human brain from that of other animals is not our tendency to believe in the supernatural, but rather our ability
not
to believe in the supernatural. Perhaps the automatic system in the brain is the innate dualist, and through acquired knowledge and education the reflective system can learn to embrace materialist explanations for phenomena that intuitively seem to require supernatural explanations.

Regardless of the neural bases of supernatural and religious beliefs, we return to the fact that they hold immense sway on our lives. In my view, too much sway to be merely piggybacking on other faculties. I suspect that religious beliefs do benefit from a privileged and hardwired status, which translates into increased negotiating power with the more rationally inclined parts of the brain. Like most complex traits, this special neural status would not have emerged in a single step, but might have evolved through a multiple step process: