The Folly of Fools (44 page)

Given the ease with which religion slides toward self-deception, what are the larger forces that might propel a religion toward more or less self-deception? One important factor is the degree to which the religion is associated with the powerful in a society. Another important force has to do with religious fragmentation. Because religions almost always preach within-religion mating, fragmentation is expected to lead to intergroup conflict over minor religious distinctions. I will argue that parasite load—average pressure on a society every generation from coevolving parasites—may be an important force fragmenting religions and thus encouraging parochial self-deception. The evidence for an association with parasite load is strong, but the evidence for a connection to self-deception not nearly so strong. First, let us turn to the positive association between religion and health.

RELIGION AND HEALTH

Religious behavior and practice appear to be positively correlated with health, a well-established fact with dozens of careful studies in support, on both sick people and well. Longitudinal studies suggest that variables such as degree of attendance at religious service are positively associated with survival years into the future.

Part of this effect may result from the tendency of religions to establish rules related to health: avoid tobacco and alcohol, pork, top predators such as sharks and lions (which tend to concentrate toxins as they move up the food chain), and generally risky or unwise behavior, such as gambling. One long-term study of US Christians showed that degree of religious attendance in 1965 predicted a change to more positive health behaviors thirty years later.

Under Islam, some behavior is prohibited, some encouraged, and some required. The forbidden (
haram
) tend to relate directly to health:

• Gambling

• Alcohol

• Eating pigs or dogs

• Eating dead meat

• Eating meat of animals not slaughtered the Islamic way (cutting throat at aorta and bleeding animal)

• Eating predatory fish

• Eating shellfish

• Usury (charging interest on money)

• Saying
oiff
to parents (an expression of impatience or annoyance), or yelling at them

• Suicide

All of the prohibitions regarding eating probably reduce parasite acquisition. Predatory fish are like sharks and lions in other religions—top predators that may be forbidden because they strongly concentrate toxins. Bleeding presumably reduces exposure to blood parasites. Only avoiding usury and saying
oiff
may not be directly related to personal health.

It is perhaps interesting to note that of the requirements in Islam (
wajeb
), three have positive connections to health (among other effects):

• Daily prayer (five times per day)

• Cleanliness (must be clean to pray: use only running water or sand)

• Fasting

• Alms to poor

• Pilgrimage to Mecca (if possible)

• Testifying (“there is only one God and Muhammad is his prophet”)

The latter three are clearly social: two showing off, and one helping a group member, all with unknown possible immune effects.

But the relation between religion and health goes deeper than health-related behavior. Some effects may come from the benefits of positive belief itself—for example, on immune function—as well as benefits that flow from being a member of a mutually supporting group, including musically supported activities that raise group consciousness, a very common feature of religion. As we have seen (Chapter 6), music has positive immune effects, while noise has negative ones. The exalting, positive music of so many religions is probably on the high end for positive immune effects (in contrast to, say, jazz or rap). Even confessing sins to God and disclosing trauma may have beneficial immune effects. The private confessional in the Catholic Church facilitates this, as do numerous public rituals of confession common to Amerindian religions. It seems likely that private, verbal confession in prayer has similar immune benefits, an example of a personal benefit to private religious behavior because it mimics a social interaction.

Whatever the precise causes, the links between religion and health seem strong enough on their own to select directly for religious behavior and belief. As biologists, we need not view religion phobically, as some negative, nonliving force of unknown nature that has us in its viruslike grip. We might remember that before the advent of modern science, almost all medicine was practiced within religion, often by special castes, medicine men and women, faith healers, and so on. Some medicinal benefits were certainly real, for example, consuming plants for their real chemical effects, a behavior that reaches deep into our monkey past (although the causal connection was usually unknown to the actors), and some may merely be the blessed placebo effect, itself probably the dominant benefit throughout two thousand years of Western medical “science.” Belief kills and belief cures.

One benefit of religion is that it does provide a framework for understanding and acting within our world, a framework we might expect to provide some psychological and mental benefits. Recent work in neurophysiology suggests one such benefit. Scientists concentrated on the anterior cingulated cortex (ACC), a region involved in many processes, including self-regulation and the experience of anxiety. EEG neural activity in the ACC was recorded while people were taking the Stroop test (name the color in which words are written, though the words denote a different color). The stronger people’s religious zeal (as measured by a scale) or the more they professed a belief in God, the less their ACC fired in response to errors and the fewer errors they made. It was as if religion was providing them a buffer against error. There must be many such possible effects.

PARASITES AND RELIGIOUS DIVERSITY

Religions have repeatedly split into subreligions that are sometimes at one another’s throats. Religions occasionally join together, but this occurs much more rarely than splitting. There is thus a bias in the propagation of religions over time, with a tendency for major faiths to split into subgroups, which may split further, typically emphasizing relatively minor doctrinal differences on which to disagree: from universal truth widely shared to smaller within-breeding units at war with each other on the basis of intellectually false distinctions. If this is an important feature of splitting—corruption of the religion’s generality and logic—then we need to understand its origins.

Recent work suggests that parasites and, in particular, parasite load may drive religions to split. These splits, in turn, entrain changes in doctrine to justify them, and thus tend to degrade the universal truth value of religion with parochial arguments whose true meaning is usually hidden. Parasite load is meant as an aggregate measure of the number of parasites and their degree of damage on a local population. Ideally, parasite load would be measured as something like the degree of overall mortality (or loss in reproduction) due to disease, but it is usually measured as a simple count of the major diseases present and the relative strength of their negative effects.

The argument goes as follows: Where parasite load is low, an in-group and out-group member may be almost equivalent where risk of transmitting a new infection is concerned, namely, low. But where parasite load is high, an asymmetry emerges. An in-group member will in general have been exposed to the same set of parasites as the other members and will carry some of the same genes that give at least partial resistance to many of these parasites. But an out-group member will be subject to selection from a slightly different set of parasites and will carry a subset to which it may be partly resistant but in-group members are not. From the standpoint of each group, the other is a threat—you may transmit your parasites to one another far faster than the genes that would protect against them. Hence, individuals in both groups may be selected to avoid one another. In short, other things equal, high parasite load is expected to increase ethnocentrism, within-group love, and hostility toward strangers. By this argument, degree of self-deception across religions and cultures is expected to correlate positively with parasite load.

What is the evidence? Two broad factors are of interest: religious and linguistic diversity. That is, how many languages and religions coexist per unit area? With high parasite load, we expect many of each, since splitting into smaller groups facilitates language formation. Regarding the evidence, there can be little doubt. Across the entire globe, religious and linguistic diversity map directly on parasite load, as does ethnic diversity—the higher the parasite pressure, the more religions, languages, and ethnic groups per unit area. The exact overlap between religion and language has not been described, but these results have been corrected for numerous possible confounding variables, and the associations remain strong and unambiguous. For language, the correlations are significant for all five of the great continents.

Canada and Brazil are roughly the same size, yet Canada has 15 religions and Brazil, 159. Canada is located in the far north, where parasite load is low; Brazil is in the American tropics, high in parasite load. Likewise, Norway, in the far north, has thirteen religions, while Cote d’Ivoire is the same size but is located in the parasite-rich African tropics and has seventy-six religions. Of course, if there is a bias toward interactions based on shared language and religion, this ought usually to intensify within-group mating, with resulting ethnic differentiation (and hostility). It is certainly striking how often out-groups are characterized as if they were flea-ridden and scabrous, if not syphilitic.

Whether this argument applies to major splits in religion is unknown. Did Shia and Sunni really split in response to parasites? And Roman and Greek Catholics? The peeling off of various Protestant sects from Roman Catholicism was associated with the publication of the Bible in modern languages, as well as with a great European outward surge of warfare, plunder, and colonialism. Where is the parasite connection, if any? Did the newly fragmented groups interact less frequently? In short, the general trend seems clear, but particular major cases may have little or nothing to do with this rule, at least given our current understanding.

One subject that requires analysis is the degree to which the formation of cities and more widespread trade conspired with monotheism to create a world less fractured along parasitic lines. We know that the appearance of agriculture and the subsequent explosion in both population numbers and rate of adaptive evolution preceded the invention and spread of monotheism, but we know little about the interaction with parasite pressure. In general, higher density increases parasite pressure, resulting in such horrors as the Black Plague, which wiped out one-third of Europe in the Middle Ages, or the influenza incubated in the trenches of World War I that consumed twenty million lives before it was done. On the other hand, we are completely ignorant of the subtler dimensions of this subject. A series of other variables have been shown to covary with parasite load, so these will very likely covary with religious features as well. High-parasite-load societies appear to be more xenophobic, more in-group oriented and homogeneous, more suppressive of women, less permissive of casual sex—in short, a suite of characteristics that can at least by logic be linked to parasite defense. So far as I know, no one has studied the interaction of these variables with religion, yet surely we would expect many connections: the more numerous religions there are in parasite-rich areas, the more the religions are expected to be xenophobic, harsh on women, conformist, and so on.

In this situation, underlying correlations are expected to bubble up from the unconscious, requiring post-hoc justification. Presumably, no one is saying, “Look, worm density has increased alarmingly in ourselves in this area for the past ten years. Perhaps it would be wise for us to be more focused on in-group interactions, including mating. Let’s up our racism level.” Instead, as I imagine it, religion provides substitute logics with similar effects—let’s emphasize minor doctrinal differences: “We scratch our asses with our right hands, they with their left [note the parasite implications], so let’s avoid the nasty left-scratchers entirely.”

WHY THE BIAS AGAINST WOMEN?

There is one important problem hidden in the above account: the assumption that in-group mating will be as strongly selected for as in-group favoritism. This is counter to expectation. We know that sexual reproduction—and the recombination it promotes—is strongly associated with evolutionary protection from coevolving parasites. Thus, parasite load may generate impulses toward in-group favoritism while at the same time heightening interest in sex with an out-group member.

Consider greater sexual promiscuity, or diversity of mating partners, well known to be higher in both birds and humans in the tropics, and presumed to represent an adaptive response to parasite load by increasing genetic quality of offspring. So why should this kind of sex be
more
prohibited in parasite-rich regions? Is it precisely because in these situations women would benefit more from such activity (improved genetic quality of their offspring) and thus provoke greater male countermoves, the kind of behavior we described so vividly in Chapter 5: mutilation, beating, terror, and murder? Certainly religions are overwhelmingly patriarchal in logic and structure, with numerous resulting effects.