Brain Buys
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Religious beliefs may have also enhanced the fitness of a group by providing an advantage during violent conflicts with other groups. An unshakable sense of unity among the warriors, along with certainty that the spirits are on their side, and assured eternity, were as likely then, as they are now, to improve the chances of victory in battle.17
It is indeed striking that virtually all ancestral and modern religions emphasize within-group cooperation. Almost any folk or modern religion could be used as an example, but let’s consider the Klamath, a hunter-gatherer tribe that occupied Southern Oregon until contact in the early nineteenth century. The Klamath transmitted their beliefs through an oral tradition rich in tales populated with talking animals and supernatural beings.18 The content of these stories is remarkable in that the main plot often revolved around starvation, presumably because of the ever-present risk of food shortage during winter. Many of these tales contrasted two individuals or animals, one dying of hunger and the other with an abundant supply of food but who was unwilling to share. The endings were invariably the same: as a result of supernatural intervention there was a proverbial reversal of fortunes, which in some stories involved the greedy party’s being turned into a rock. These were not subtle stories; they clearly had the goal of instilling the importance of sharing resources in the hope of maximizing the survival of the tribe. Presumably the oral transmission of these stories contributed to survival not only because they inculcated altruistic behaviors among tribe members, but also because the Klamath believed that they might actually be turned into stone if they did not share their food.
The within-group altruism characteristic of most religions often stands in stark contrast to the prescribed conduct toward outsiders. For instance, in Deuteronomy (15:7–8) the Bible states:
If there be among you a poor man of one of thy brethren within any of thy gates in thy land which the LORD thy God giveth thee, thou shalt not harden thine heart, nor shut thine hand from thy poor brother. But thou shalt open thine hand wide unto him, and shalt surely lend him sufficient for his need, in that which he wanteth.
In the face of battle with the neighboring state, however, Deuteronomy (20:13–16) instructs:
when the LORD thy God hath delivered it into thine hands, thou shalt smite every male thereof with the edge of the sword. But the women, and the little ones, and the cattle, and all that is in the city, even all the spoil thereof, shalt thou take unto thyself; and thou shalt eat the spoil of thine enemies, which the LORD thy God hath given thee. Thus shalt thou do unto all the cities which are very far off from thee, which are not of the cities of these nations. But of the cities of these people, which the LORD thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth. But thou shalt utterly destroy them.
David Sloan Wilson argues that group selection provides the best (but certainly not the only) hypothesis to understand this apparent paradox.19 Mercy and kindness within a group coupled with mercilessness between groups makes sense under group selection. Members within a group are likely to share “religious genes,” so, in effect, helping thy neighbors might also help propagate the religious genes. From this perspective, however, generosity toward outsiders who might not have the same “religious genes” amounts to squandering precious resources that could be used for oneself.
“THE WISDOM TO KNOW THE DIFFERENCE”
The argument that religious beliefs were selected for because they enhanced within-group cooperation is a compelling one.20 However, the notion of group selection in general remains a controversial hypothesis because it has a serious loophole: defectors or free riders.21 If everybody in a group has the genes that underlie the religious beliefs that lead to cooperation, group selection is on fairly solid ground. If a few individuals don’t have those genes, however, they will reap the benefits of living among altruists, but not pay the individual costs of cooperation, such as sharing their food or dying in war. These individuals will eventually out-reproduce the altruists in the group and undermine the premise of group selection. There are a number of theoretical “fixes” for this problem, including the possibility that continuous warfare could from time to time wipe out tribes with too many defectors or that free riders would be punished by other members of the group. But an additional problem is that the genes that encourage religiosity would have to be present in a significant percent of the population for the group selection to come into effect. How would this come to be, if these genes don’t afford any advantage to the individuals?
Richard Dawkins has stated, “Everybody has their own pet theory of where religion comes from and why all human cultures have it.”22 I will now prove him correct by offering my own suggestion as to how, very early in human evolution, “supernatural genes” could have been adaptive to individuals. Once these genes were in place, they could have served as a platform for the further selective processes operating at the level of groups.
The computational power of the brain expanded throughout human evolution, apparently culminating with Homo sapiens. At some point in this process we started to use our newly acquired neocortical hardware to do something quite novel and bold: to ask and answer questions. As humans began to pose and solve problems, indulging one’s curiosity could pay off. Primitive man figured out how to make fire, build and use tools, deceive enemies, and develop agriculture. Intelligence and curiosity are ultimately the reason we now live in a world that is radically different from that in which we evolved. All modern technology is the product of a cumulative sequence of intellectual advances, driven by a presumably innate desire to ask and answer questions. But as many of us know firsthand, the ability to ask and attempt to answer questions can also be a momentous waste of time and energy.
“Hummm…here ground is muddy like near a river, maybe water in ground, me dig,” is potentially a fruitful train of thought for a thirsty Homo erectus (an ancestor of Homo sapiens that survived for over a million years), and perhaps even meritorious of a research grant in the form of help from some band mates. On the other hand, “Me very thirsty, rain comes from loud clouds in sky, how make clouds?…maybe if make rumbling sounds like thunder” is less worthy of funding. At any given time and place there are questions that have a chance of being answered within the lifespan of the individual, and others that do not. For primitive man, asking if he can make fire, use a stone to sharpen another, or wondering if a fruit-bearing tree would emerge from a seed are excellent questions—ones that are not only within his reach but that would likely increase survival and reproduction. In contrast, asking how to make it rain may not be the most productive way to spend his free time, nor would trying to figure out why, from time to time, the bodies of some members of the tribe become unresponsive and grow cold. Simply put, some questions are better off not being asked, or at least we are better off if we do not waste our time attempting to answer them. As early humans developed an increasingly impressive capacity to pose and answer questions, there may have been a very real danger of prematurely becoming philosophers—pondering mysteries outside their grasp. Evolution would have favored pragmatic can-do engineers.
But how could primitive man know which questions were likely to bear fruit and which would be barren? Perhaps brains that could compartmentalize problems into two distinct categories—which today would correspond to natural and supernatural phenomena—would be better able to focus their newly acquired cognitive skills toward productive questions and avoid wasting time trying to understand the incomprehensible and attempting to change the unchangeable. The well-known serenity prayer requests that God grant the “wisdom to know the difference” between the things that can and cannot be changed.23 In a way, natural and supernatural labels provide such wisdom: the natural is potentially within our control, whereas the supernatural is far outside our control. Undoubtedly our ancestors did not distinguish between natural and supernatural phenomenon in the way we do today, but it may have been adaptive to consciously or unconsciously discern between doable and undoable ch
allenges. Which problems belong in each category could have been determined across generations and relied on cultural transmission.
The evolution of another computational device, digital computers, is illustrative. The invention of computers was a revolutionary turning point in modern technology. Much like the emergence of the modern brain in hominin evolution, computers and the Internet produced a game-changing shift in what is doable. The minds that contributed to the creation of computers and the World Wide Web suspected as much. They probably did not anticipate, however, that one of the most common uses of these technologies would be to allow anybody on the face of the planet to play Warcraft with any other person on the planet, or to have instant access to erotica. Video games and pornography were not originally planned or foreseen functions of computers. But any sufficiently powerful technology will be put to use for purposes other than those it was originally designed for. My point is that there was a real possibility that the newly granted computational power of the neocortex of early man could have been diverted toward applications with no adaptive value: daydreaming, collecting butterflies, playing Dungeons & Dragons, or trying to find the ultimate answer to “life, the universe, and everything.” Valid pursuits perhaps, but unlikely to increase your share in the gene pool when faced with obligatory activities, such as finding, yet not becoming, food.
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.