Religion and Evolutionary Fitness


The practice of religion interrupts the human preoccupation with self-serving activity—which suggests that one function of religion is to keep people from being too obsessed with their personal interests. But why should that obsession, which confers an advantage in evolutionary fitness, be prevented?  Could there be a countervailing advantage in being relieved from the same obsession? Or does this aspect of religion perhaps decrease human evolutionary fitness?  It is a mistake to assume that every characteristic which takes hold in a population increases fitness. Daniel Dennett’s book on the memetics of religion, Breaking the Spell, opens with a counter-example:

You watch an ant in a meadow, laboriously climbing up a blade of grass, higher and higher until it falls, then climbs again, and again, like Sisyphus rolling his rock, always striving to reach the top. Why is the ant doing this? What benefit is it seeking for itself in this strenuous and unlikely activity? [Dennett, 2006, p 3]

The answer, it turns out, is no benefit—to the ant! Its grass-climbing behaviour is prompted by a tiny parasite, a lancet fluke, that has penetrated its brain. In order to complete its reproductive cycle, the fluke must find its way into the digestive system of a sheep or cow. By commandeering the motor apparatus of its host the ant, the fluke puts itself in the way of being grazed.

Dennett’s book takes as its starting point Richard Dawkins’ observation that the memes of human culture, like genes, are replicating entities whose populations wax or wane according to principles of natural selection.[Dawkins, 1976]  Among the memes that thrive or die are religious ones. The provocative question animating Dennett’s discussion of religion is, “What is the relationship of religious ideas to their human hosts? Do religions benefit their believers, are they neutral, or are they—like the lancet fluke to the ant—deleterious parasites?”

The answer is obvious. Religious belief has not had an adverse effect on human reproductive success. We know that parents’ religious affiliation, or lack thereof, is the most significant determinant of the affiliation of children.[Dennett, 2006, p 86] Religion, like hepatitus B, is transmitted mainly from parent to child; it is not easily caught, as is the flu, from unrelated individuals. That fact combined with religion’s prevalence in the human population (about 85%) ensures that religion’s impact on fitness cannot be negative. It might be neutral; but the costliness of religion, which inevitably demands sacrifices of time and money from its adherents, strongly suggests there must be some balancing benefit. (I use the term “benefit” in the narrow sense meaning anything that favours reproduction and survival of offspring.)

Memetics of Religion

The science of natural selection concerns the features of replicating entities which affect their differential fitness—their reproductive success in a competitive environment. To understand the evolution of religion, we must consider two kinds of replicators, one of which is biological—the human animal—the other being the religious memes (beliefs and practices) that replicate in the environment of human minds. The question, “How did religion evolve?” has two sides. Not only should we ask what is the impact of religion on human evolutionary fitness, we must also ask what features of religious memes impact their reproductive success.

If the biological function of the concept of self is primarily motivational, and religion is an antidote to the self, we should expect human motivation to be a central concern of religion—as, of course, it is. In the previous post, I argued that the idea of self is destructive to human happiness, and that religion, in weakening the motivational force of self-concern, can help counter that effect. Moreover, I suggested that the motivational self may be in some respects deleterious to human evolutionary fitness. If that were true, it could explain why religious participation, despite its high cost, has caught on so successfully. If self-concern began to impact human fitness negatively, then religion, as a means of keeping self-concern in check, might have a corresponding positive effect.

Earlier, I argued that the evolution of self-concern originally enhanced human evolutionary fitness—that the human ability to imagine oneself in various future scenarios, and be strongly motivated by one’s imagined fate in those scenarios, was like the development of a thermonuclear bomb in the evolutionary arms race. It allowed the human population to expand by orders of magnitude, to the point that it has crowded most other large species—except ones we have domesticated—into marginal niches. Many have gone extinct, and many more will do so, while we have become the undisputed alpha species on this planet.

Could the same characteristic that has had such a positive impact on our species’ fitness also have a negative impact?  Could the motivational self become a victim of its own success?

I think the answer is yes, and an explanation lies in the fact that the human species is social. Our evolutionary success depended on social cooperation, and continues to do so. High intelligence, an ability to plan for the future, and an emotional apparatus that makes mental images involving ourselves in the future almost as strongly motivating as our perceptions of the real scene in which we find ourselves, were not enough to propel us into the position of global dominance we enjoy today. The human animal, physically adapted first to tree-climbing, then to a hunter-gatherer life on a tropical savannah, is poorly endowed with natural defences and weaponry. E.O. Wilson describes our ancestral populations as:

…very small, of a size that in the course of mammalian history carried a probability of early extinction. [Wilson 2012, p. 13]

Despite these shortcomings, not only did we thrive, we have succeeded in transforming our environment in ways that make it vastly more hospitable to humans, creating a situation in which hardly anyone is ever threatened by large predators, and many people’s food supplies are secured for the foreseeable future. If developing emotional concern for our future selves was our thermonuclear weapon in the evolutionary arms race, the advent of settled agrarian economies was our missile defence shield, which erected effective barriers between human communities and the jungle outside.

Group Selection for Altruistic Traits

‘Group selection,’ a variety of natural selection, is a centre of controversy in evolutionary biology. From the 1970’s until a few years ago, the concept was decidedly out of favour. To express interest in group selection was as fatal to a career in evolutionary biology as a defence of Lamarckism. But recent work has attached clear scientific sense to the concept, and given it a new respectability.

There is an ongoing debate about what is the target of natural selection—about what entity, exactly, natural selection selects. Sometimes the target is described as genes, sometimes as individual biological organisms, sometimes as species. Undeniably, the gene is the replicating entity which is passed from one generation to another, its numbers either increasing or decreasing in the process; as a result, a ‘gene-centric’ view is needed for an understanding of the mechanics of natural selection [Dennett, 1995, p. 326]. But individuals and species are other functional units which cannot be omitted from an explanation of natural selection. That is because natural selection only takes place when there is competition; and competition takes places at different levels of organization. I use the word “competition” broadly to refer to any contest in which differential fitness is manifested—including competition for a limited resource, such as food or territory; predation, in which the defences of the prey are pitted against the offensive weaponry of the predator; and parasitism, which is predation from within. The gene-centric view is not very useful for explaining the role of competition in natural selection. Competition takes place between individual organisms, between species, and between groups of organisms belonging to the same species. Competition at any of these levels of organization can result in natural selection—of genes.

Daniel Dennett offers a “minimalist” definition of natural selection consisting of three factors:

(1)   variation: there is a continuing abundance of different elements

(2)   heredity or replication: the elements have the capacity to create copies or replicas of themselves

(3)   differential “fitness”: the number of copies of an element that are created in a given time varies, depending on interactions between the features of that element and features of the environment in which it persists [Dennett, 1995, p 343]

Competition is not emphasized in Dennett’s definition, but it is there, buried in clause (3), for competition is what causes differential fitness. Without competition, all replicating elements would replicate without contraint, and natural selection would not occur.

Individual competition takes place when animals vie for mates. The peacock with the most impressive tail attracts the most females, with the result that his genes (all of them, including the impressive-tail genes) replicate more than those of his rivals. Species-level competition occurs whenever a transplanted species proves better at exploiting an ecological niche than the native species which predates it, in doing so, it earns the title, “invasive.” Competition between species, leading to extinctions, is a primary driver of the facts of evolution facts Darwin sought to explain in The Origin of Species, long before much was known about the genetic mechanism of inheritance.

Evolutionary biologists have invoked group selection in order to explain the evolution of altruistic traits in humans and other species. They define altruism narrowly as behaviour that benefits the group but harms the individual. An individual acts altruistically, in this sense, if his act decreases his genetic fitness (by risking his life, perhaps), while improving, or aiming to improve, the fitness of the group.

Opponents of the group selection idea sometimes say that altruistic traits meeting this definition cannot evolve by natural selection. Their argument goes like this: in any population in which an altruistic trait appears, individuals who lack the trait (‘cheaters’) will, by definition, have greater fitness. Hence any trait that meets the definition of altruism will inevitably disappear from the population. It follows that surviving traits that appear to be altruistic, in fact are not; their very survival is proof that they benefit individual fitness.

But this explanatory model is flawed, for it ignores the effects of group competition.

In a new book, The Social Conquest of Earth, E.O. Wilson presents a framework for evolutionary biology in which group selection is a major force. Wilson asks “why advanced social life exists at all, and has occurred so rarely in the history of life,” and what are the mechanisms by which it came to exist? Very few terrestrial species have achieved the level of social organization which Wilson calls “eusociality,” characterized by multiple generations joining forces in a colony that inhabits a persistent, defensible residence, in which individuals adopt specialized behavioural roles that contribute to group success. Those species that have done so include some with the greatest ability to shape their environment, and the highest impact on competing species.

When you look at the full panorama of social behavior in the animal kingdom, and not just the part of it represented by human beings, a pattern stands out sharply. Seldom considered by evolutionary biologists in the past, it comprises two phenomena connected by cause and effect. The first phenomenon is that animals of the land environment are dominated by species with the most complex social systems. The second phenomenon is that these species have evolved only rarely…. They have arisen through many preliminary steps across millions of years of evolution. Humanity is one of the animal species. [Wilson, 2012, p 109]

Wilson charts two distinct evolutionary paths to eusociality, one taken by the social insects, the other by ourselves. Social organization of ants, bees and wasps is built around reproductive specialization: most eusocial insect colonies have a single queen. The small size of individual insects limits their intelligence, and hence, their adaptability; their behaviour is a mostly inflexible expression of their genes. Because of the close genetic relatedness enforced by their reproductive constraints, Wilson argues, the eusocial insect colonies are best thought of as single organisms, or “superorganisms,” whose origin and evolution can best be understood as “processes driven by individual-level natural selection.” [Wilson, 2012, p 143. Emphasis added]

Wilson argues persuasively that eusociality in human groups, in which all normal members compete to reproduce, is a product of true group selection.  He cites a 2009 paper by Samuel Bowles which showed not only the theoretical possibility, but evidence for the actual occurrence of, natural selection for altruistic traits as a consequence of warfare between human groups.

Bowles set out to test Darwin’s intuition that groups with “a greater number of courageous, sympathetic and faithful members, who were always ready to warn each other of danger, to aid and defend each other…would spread and be victorious over other tribes,” leading to selection of altruistic traits. [Darwin, 1873, p 156]

Bowles devised a mathematical model to show the theoretical possibility that genetic natural selection of altruistic traits can occur as the result of group conflict. The model assumes that groups with a higher proportion of altruistic individuals are likely to prevail over similarly-sized groups with fewer altruists, and that victory of a group improves the evolutionary fitness of its members compared to the losers, both because of higher mortality in the losers and because of advantages accruing from the winners’ gains in territory. The question then becomes whether this positive selection for altruistic genes outweighs the negative selection pressures resulting from the costs of altruism. Bowles draws on archaeological studies of conflict between hunter-gatherer tribes in the past twelve thousand years, a period yielding relatively complete and reliable data, to show that mortality rates from such conflicts are high enough to create positive net selection pressures for altruism. Assuming that conflicts between Paleolithic hunter-gatherer groups were similar to these comparatively modern conflicts, the evolution of human altruism can be explained.

There is an intriguing, because counter-intuitive, irony in Bowles’ findings that warfare acts as an evolutionary crucible for selection of the sterling moral qualities of cooperation and self-sacrifice for the general welfare!

But lethal conflict is not necessary to Bowles’ theory: any inter-group competition can play the same role. If, as Wilson suggests, the traits of cooperation, organization, and trustworthiness confer an advantage to hunting parties [Wilson, 2012, p 40], Bowles’ model shows how those traits could become dominant. If hunting parties containing a higher proportion of cooperators, loyal to the group, outperform rival parties containing more freeloaders and shirkers in competition for limited game, the net effect is that groups heavy in cooperators eat and breed while groups with a preponderance of shirkers go hungry. In a context of group competition, natural selection cuts two ways, towards both selfishness and altruism, with the outcome depending on the relative advantage conferred on each.

Is Religion a Product of Group Selection?

The creation myth is a Darwinian device for survival. Tribal conflict, where believers on the inside were pitted against infidels on the outside, was a principal driving force that shaped biological human nature. The truth of each myth lives in the heart, not in the rational mind. By itself, mythmaking could never discover the origin and meaning of humanity. But the reverse order is possible. The discovery of the origin and meaning of humanity might explain the origin and meaning of myths, hence the core of organized religion. [Wilson, 2012, p 8]

Could religion—a cultural artifact that exerts a profound influence on human behaviour, favouring altruism and punishing selfishness—be a product of group selection?

Bowles makes the telling point that his model works for behaviours transmitted culturally as well as genetically, even “with greater force,” because cultural differences between human groups tend to be greater than genetic ones, “and hence the evolutionary impact of differential group success in contests is stronger.” [Bowles, 2009, p. 1297]  Bowles says nothing specific about religion, but the reader may infer that if religious belief strengthened a group by enhancing social solidarity, it would spread about as fast as the group propagates biologically.

E.O. Wilson sees religion as a practice which allows a tribe to strengthen itself in the face of inter-tribal competition.

The evidence that lies before us in great abundance points to organized religion as an expression of tribalism. Every religion teaches its adherents that they are a special fellowship and that their creation story, moral precepts, and privilege from divine power are superior to those claimed in other religions. Their charity and other acts of altruism are concentrated on their coreligionists; when extended to outsiders, it is usually to proselytize and thereby strengthen the size of the tribe and its allies. No religious leader ever urges people to consider rival religions and choose the one they find best for their person and society. … The goal of religions is submission to the will and common good of the tribe. [Wilson, 2012, pp 258-259]

Wilson thinks that religion, as a pathway to the social virtues, is better suited to a bygone era than to our own. If religion is a product of natural selection, then

…religious faith is better interpreted as an unseen trap unavoidable during the biological history of our species. And if this is correct, surely there exist ways to find spiritual fulfillment without surrender and enslavement. Humankind deserves better. [Wilson, 2012, p 267]

An intriguing aspect to the group selection theory of altruistic motivation is that it offers an explanation for the well-known conflict within the human breast, documented by moralists, theologians, poets, psychologists and cartoonists—who typically depict it with two miniature copies of the morally conflicted protagonist, one wearing white wings and a halo, the other with horns and a pitchfork, each whispering into one ear. We are often pulled in two directions, between concern for others or for a greater good, and concern for ourselves. This tension—the universal moral struggle that gives meaning to so much of our art, and to our lives—may now be seen as the interaction of two opposed forces of natural selection, one favouring the individual and the other favouring the group. Both shape us; both are our heritage; both are expressions of, ultimately, the same process, that gave rise to the immense diversity of life.

Correcting the Imbalance

The evidence suggests that religion did not evolve as a parasite, damaging its human hosts, but as a fitness-enhancing symbiont. In Paleolithic times, and much later, religion played a positive role in strengthening human groups in their competition with rival groups, and with other animal species. The evidence is at least as clear that another belief, motivational identification with one’s imagined future self, also enhanced the fitness of early humans.

Awareness of their future selves spurs people to work hard to promote their private interests, but does nothing to strengthen the social fabric into which their individual lives are woven, and on which they completely depend. The self remains an overwhelming motivator because people continue to believe in it strongly and uncritically. Belief in God—a personal God, who is interested in our lives, and promises consequences for good or bad behaviour—is, nowadays, a sketchier proposition. For those of us schooled in a scientific outlook, who side with the Copernican rebels against the Ptolemaic traditionalists, and who delight in the insights flowing from the hypothesis that blind, random selection of replicating entities is an engine of design, belief in such a personal God is impossible. And God only motivates those who believe in Him.

Some modern defenders of religion reply that the anthropomorphic God of Abraham is a outdated idea which they have moved beyond—that their concept of God is compatible with a scientific worldview. After all, the universe exists, although it might not have; moreover, it is ordered in exquisite ways, not the least of which is the order that supports the amazing creative process of natural selection. Should we not revere the principles—whatever they may turn out to be, when science has completed its work of discovery—that make all this possible?  Of course we can do this, and it strikes me as not unlike being impressed with the wonder and beauty of physical law, as scientists often are. That’s what draws them to choose science, instead of using their talents to make a fortune in business. But such an abstract view of God gives us very little moral guidance. Belief in such a God—who does not care what we do, in the way that a parent or chieftain would care—does little or nothing to maintain the bonds of trust which allow us to cooperate effectively in our complex economies. If Wilson is right, it lacks the most important features that religious memes need to replicate successfully in their natural environment of human groups.

In making it impossible to believe in a personal God, science has kicked off one shoe—if I can use that metaphor for a foundation myth that bolstered the precarious fortunes of our prescientific ancestors—leaving us motivationally unbalanced. Progress demands that we lose the mate of that hoary shoe—the other ancient belief that drives us with visceral fear and yearning dreams. The self—that kind of self—does not exist.


Bowles, Samuel (2009), “Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?” Science vol. 324

Darwin, Charles (1873) The Descent of Man, Appleton & Co., New York

Dawkins, Richard (1976), The Selfish Gene (3rd ed., 2006), Oxford University Press, Oxford.

Dennett, Daniel (1995) Darwin’s Dangerous Idea, Simon and Schuster, New York

Dennett, Daniel (2006) Breaking the Spell, Penguin Books, London

Wilson, Edward O. (2012), The Social Conquest of Earth, Liveright Publishing Corp., New York


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5 Responses to “Religion and Evolutionary Fitness”

  1. Tim Allen says:

    Wow, that was a hell of a read (no pun intended). And this may get a tad sappy..

    I guess we’re second cousins, but we’re bird of a feather. Mom always said you were here favorite cousin and I guess that makes us – whatever at this point. I still remember mom telling me about your view of SEPTA train lines, and how none of them – in the shoddy shape – would be allowed to exist under your watch. I remember thinking the same thing when looking at the tracks my whole life.

    That said – I’m fairly anti-religious. You don’t take your views to that point, but I will: if Natalia is forced to live in a world where idiot zealots rule the planet, this will be a bad thing. I’ll have her back, trust me.

    The modern religion is political, and it is a horrible thing. It is no longer a moral code, or a force for good… it is a force for the ultimate $$$ and horrid in that respect. The philosophy behind religion is no longer there; the good spirit and the need to create for the better good is long gone.

    This is why I have grown up to be a happy agnostic (I’m not sure if my mom, your cousin, is proud of this or afraid of where the church will head). However, my Uncle Gordon, I hope you know this: I read your blog. I’ve met you what, three times? If my mom says I should pay attention to you, I will. She’s frickin’ smart as hell, and so are you. I’ve enjoyed the conversations we’ve had. And I hope you pull through this. If you don’t, let me know what I can do.

    If there’s ever anything I can do for you – let me know.

    I may never be in your neck of the woods, but I’m visiting Montreal (since Canada is so small, right?) from August 8-12th, but I’ve got your back, and I respect everything you’ve done. You’ve inspired me.

    Again, sorry to get sappy – but when mom says to pay attention to someone, I do. And you have been an inspiration.



  2. […] My Cousin Gordon on Science and Religion So I must share this; my mom’s cousin Gordon is kind of a genius. I felt this passage from his blog was particularly… […]

  3. Jan Beck says:

    There are two statements in your opening paragraph that I”m shaking my head over. Certainly if A, then B, but we’ve not established the validity of A, and therefore cannot establish the validity of B. So please, do so first. That gives the rest of your viewpoint overall validity. The first premise is
    “The practice of religion interrupts the human preoccupation with self-serving activity”

    I could say there has been self-serving practice down through the ages in the Catholic Church as well as what I see today in the Christian communities. Isn’t that what the TV evangelist is doing when he/she stands infront of a monitor, tears running down their face as they implore you to send in your money? In fact, I find it more often in churches than I do in other places.

    2nd premise
    But why should that obsession, which confers an advantage in evolutionary fitness, be prevented?

    Short answer here is, it doesn’t. “IF” this was true, there would be no evolutionay advantage. In early studies, during the 70’s, it was shown that altruism does indeed begin at home and spread out through your family group. One is more likely to be kind and giving to a family member, amount depends on how close that family member is. cousins not as much as siblings.

    wow, I’ve not thought about this stuff for many years…this is kinda fun.
    I hope this message finds you well, and your day is good

  4. Fair comment, Jan. I didn’t mean to suggest that activities that go by the name of ‘religion’ are never self-serving. But all the religions I know of seek, in explicit doctrine and moral teaching, to suppress human selfishness and promote some form of unselfish motivation.

    I do think that the human obsession with personal interests has contributed to the undeniable evolutionary success of our species. It’s because we are so strongly motivated to worry about our personal futures that we put so much energy into planning for the future. I agree with you that that is not ALL that motivates us, and that group selection for altruistic traits played an important role our motivational evolution. The human propensity towards religious belief may have been selected for in this latter way.

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