Homo Mysterious: Evolutionary Puzzles of Human Nature (42 page)

It probably isn’t a coincidence that many religions require not only that their devotees give money, or a commitment of time, but that they undergo painful rites, often involving genital mutilation—known less pejoratively as circumcision. An important consideration in evolutionary biology revolves around the question of “honest signaling.” The idea is that it is easy, perhaps too easy, for an individual to communicate something about himself: how healthy he is, or what a good father he would be, or what a reliable partner in other respects. Since talk is cheap, in many species natural selection has favored messages that cannot readily be faked, such as a deep croak among toads (small individuals are limited to higher frequencies), fancy feathers among peacocks (weak individuals cannot muster the energy to grow such outlandish accoutrements), and so forth. Maybe even Groucho Marx would trust membership in a religion that demanded as much of its congregants.

In many human interactions—perhaps most of them—participants are vulnerable to being deceived by others. Interactions often involve what evolutionary biologists call “reciprocal altruism,” in which someone helps someone else, at some cost to the helper (the initial altruist). But such behavior can be richly rewarded—and thus not actually be altruistic at all—if the initial recipient pays back her debt when the tables are turned, and the altruist is needy and the recipient is in a position to repay the debt. Such systems are vulnerable to exploitation, however, if the beneficial reneges on her obligation and refrains from repaying the initial donor. Although it is often possible to protect oneself from social predators, effective defenses are time and energy consuming; it is more efficient, albeit far from foolproof, to rely on shared membership in the same social club, ideally one that has already established certain ethical rules of the road. And it is at least possible that religious affiliation sometimes fills this role, generating trust that coreligionists are less likely to renege on their reciprocal obligations. This would help make sense of the widespread assumption that religion is somehow a prerequisite for moral behavior.

In public opinion polls, for example, Americans have consistently said that they would prefer to vote for a president who is of their own religious faith, but overwhelmingly, that they would rather vote for someone of a different faith than for an atheist. President Dwight Eisenhower (not especially devout himself) reportedly opined that the US government only makes sense insofar as it is founded on “a deeply felt religious faith,” adding “and I don’t care what it is.” Even in such a supposedly secular venue as a US court of law, witnesses routinely swear to tell the truth on a Bible, adding “so help me God.”

The assumption that religiosity is intimately connected to moral reliability isn’t new, nor is it limited to the United States, which is—for better or worse—the most devout country in the Western world. Thus, when John Locke, one of the preeminent philosophers of tolerance, religious and political, penned his celebrated
Essay Concerning Toleration
(1689), he explicitly excluded atheists from his list of those who merited tolerance: “Those are not at all to be tolerated who deny the being of a God. Promises, covenants, and oaths, which are the bonds of human society, can have no hold upon an atheist.”

According to historian Edward Gibbon, writing about a century after Locke, “The various modes of worship, which prevailed in the Roman world were all considered by the people as equally true; by the philosopher, as equally false; and by the magistrate, as equally useful.”

Most observers of religion agree that when it comes to morality and ethical behavior, the balance sheet of most religions is difficult to interpret, although it is plausible that the “usefulness” of religion extends to natural selection (operating presumably on groups), no less than to Roman magistrates (presumably operating via its effect on rendering social relations more predictable and citizens more law abiding). Religions certainly claim to be a source of positive moral values, and they are typically perceived as such by their proponents. On the other hand, religious persuasion can be a source of intolerance and violence, and no small amount of hypocrisy. It is one thing, however, to ask whether, on balance, religions are morally beneficial, yet something different to inquire whether they are
biologically
beneficial by virtue of their moral teaching and
the social confidence and coherence—whether objectively justified or not—that they generate.

In summary, the jury is still out on whether religion evolved via group selection, which, in turn, might have favored those groups that were more violently cohesive during war and morally cohesive during peace. It seems highly likely, however, that natural selection, whether acting at the level of individuals or of groups, has been responsible for the existence as well as the perseverance of religion.

If so, it may also have been responsible for one of the more peculiar and fascinating aspects of our mental lives: the fact that we are such divided creatures, capable of both extraordinary rationality and critical thought on the one hand and blind, unquestioning faith on the other—and the fact that when it comes to religion, the latter typically predominates. No less a skeptical rationalist than David Hume famously noted that “reason is and ought only to be the slave of the passions.” The “is” part seems clear, and not surprising. After all,
Homo sapiens
and probably its antecedents as well have been practicing various forms of religion for tens of thousands of years, whereas scientific inquiry, for example, is only a few centuries old. It is just barely 150 years since Darwin’s
Origin of Species
. Our understanding of the microbial basis of disease is even newer. Relativity is only about a century old, and we’ve only started using computers.

The passions—religious and otherwise—are much older, and their roots are deep indeed.

The likelihood is that on balance, religion was adaptive for human beings, at least in the past. But is it still? Clearly, in some cases it has been grotesquely maladaptive: parents in Jonestown, Guyana, poisoning their children and themselves, followers of “Heaven’s Gate” castrating and then killing themselves—all the better to be whisked away onto the passing comet, Hale-Bopp, and so forth. As to other, more mainstream religions, the jury is still out, and the question goes beyond the purview of the current book.

A useful metaphor might be found—strangely enough—in the human fondness for sugar. Why is sugar sweet? For the evolutionary biologist on the lookout for ultimate explanations, the answer does not involve glucose, sucrose, fructose, and so forth, all of which are chemicals that give rise—proximally—to the sensation of sweetness when consumed by a human being. After all, an anteater would probably protest that sugars aren’t sweet at all; rather, ants are.

Sweetness, when it comes to evolutionary considerations, is thus in the mouth of the taster. Anteaters have been honed by natural selection to be positively influenced by the taste of ants, just as giant pandas adore bamboo shoots and koalas are partial to eucalyptus. Almost certainly, members of the species
Homo sapiens
find sugars sweet because we are primates, who evolved as fruit eaters, and fruit, in turn, is maximally nutritious when ripe, and ripeness correlates with being sugar laden (so as to attract birds and mammals—including primates—which spread their seeds after eating them).

Today, people can indulge their species-wide sweet tooth, a preference that was clearly adaptive among our ancestors, but by consuming “empty calories” in the form of cakes, cookies, candies, and soft drinks. The result is an adaptive inclination gone awry, especially since we no longer need ripe fruit as a major source of calories, on top of the fact that our ingenuity has endowed ourselves with the ability to cater to a “need” without conveying any of the original payoff. In fact, it does us harm.

Is there something similar in our predisposition to religion? Thus, although we cannot as yet conclude which biological factors made religion adaptive in our species’ infancy, it is at least possible that it—or some behaviors currently subsumed under the term
religion
—was once adaptive. But just as a fondness for sweets used to be adaptive but is now troublesome and sometimes downright dangerous, the same may apply to religion. Of course, our penchant for sweetness can be used for our benefit—as in the
Mary Poppins
song, “a spoonful of sugar makes the medicine go down”—there can be substantial beneficial aspects of religion, too.

Also, just as there are substitutes for sugar—saccharine, aspartame, etc.—aren’t there also substitutes for religion? These chemical substitutes are sought because of the payoff to satisfying the
craving but without the undesired calories; is there an equivalent for religion? Interestingly, devotees have argued for various “sugar substitutes” such as LSD, marijuana, or psilocybin, although no one has thus far come up with “God in a pill” as satisfying as that which—somehow or other—natural selection managed to invent.

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C
HAPTER
N
INE
On the Matter of Mind

W
HEN IT COMES TO
constituting a hallmark of the human species, the opposable thumb just isn’t very impressive. Ditto for our largely hairless torsos and even our bipedalism. What stands out, far more, is our big brains and our capacity for sophisticated thought. Yet we know very little about thought itself, neither how we go about it as individuals, nor what caused us as a species to have evolved into such highly cognitive creatures. Accordingly, here is paradox along with mystery: As clever as we are, we aren’t smart enough to figure out why we became so clever! Consistent with our approach throughout
Homo Mysterious
, in this chapter we’ll focus on the evolutionary side of the mystery: Why did natural selection make us—at least by our own standards—the smartest species on earth?