Edward O. Wilson

Evolution and Our Inner Conflict

6/24/12

Are human beings intrinsically good but corruptible by the forces of evil, or the reverse, innately sinful yet redeemable by the forces of good? Are we built to pledge our lives to a group, even to the risk of death, or the opposite, built to place ourselves and our families above all else? Scientific evidence, a good part of it accumulated during the past 20 years, suggests that we are all of these things simultaneously. Each of us is inherently complicated. We are all genetic chimeras, at once saints and sinners — not because humanity has failed to reach some foreordained religious or ideological ideal — but because of the way our species originated across millions of years of biological evolution.
Kin selection alone doesn’t adequately explain our complex natures.Don’t get me wrong. I am not implying that we are driven by instinct in the manner of animals. Yet in order to understand the human condition, it is necessary to accept that we do have instincts, and will be wise to take into account our very distant ancestors, as far back and in as fine a detail as possible. History is not enough to reach this level of understanding. It stops at the dawn of literacy, where it turns the rest of the story over to the detective work of archaeology; in still deeper time the quest becomes paleontology. For the real human story, history makes no sense without prehistory, and prehistory makes no sense without biology.
Within biology itself, the key to the mystery is the force that lifted pre-human social behavior to the human level. The leading candidate in my judgment is multilevel selection by which hereditary social behavior improves the competitive ability not of just individuals within groups but among groups as a whole. Its consequences can be plainly seen in the caste systems of ants, termites and other social insects. Between-group selection as a force operating in addition to between-individual selection simultaneously is not a new idea in biology. Charles Darwin correctly deduced its role, first in the insects and then in human beings — respectively in “On the Origin of Species” and “The Descent of Man.”
Even so, the reader should be warned that the revival of multilevel selection as the principal force of social evolution remains a hotly contested idea. Its opponents believe the principal force to be kin selection: when individuals favor kin (other than offspring), the evolution of altruistic behavior is favored. The loss suffered by the genes of the altruist are compensated by genes in the recipient made identical by common descent of the altruist and recipient. If the altruism thus created is strong enough it can lead to advanced social behavior. This seems plausible, but in 2010 two mathematical biologists, Martin Nowak and Corina Tarnita, and I demonstrated that the mathematical foundations of the kin selection theory are unsound, and that examples from nature thought to support kin selection theory are better explained as products of multilevel selection.
A strong reaction from supporters of kin selection not surprisingly ensued, and soon afterward more than 130 of them famously signed on to protest our replacement of kin selection by multilevel selection, and most emphatically the key role given to group selection. But at no time have our mathematical and empirical arguments been refuted or even seriously challenged. Since that protest, the number of supporters of the multilevel selection approach has grown, to the extent that a similarly long list of signatories could be obtained. But such exercises are futile: science is not advanced by polling. If it were, we would still be releasing phlogiston to burn logs and navigating the sky with geocentric maps.
I am convinced after years of research on the subject that multilevel selection, with a powerful role of group-to-group competition, has forged advanced social behavior — including that of humans, as I documented in my recent book “The Social Conquest of Earth.” In fact, it seems clear that so deeply ingrained are the evolutionary products of group selected behaviors, so completely a part of the human condition, that we are prone to regard them as fixtures of nature, like air and water. They are instead idiosyncratic traits of our species. Among them is the intense, obsessive interest of people in other people, which begins in the first days of life as infants learn particular scents and sounds of the adults around them. Research psychologists have found that all normal humans are geniuses at reading the intentions of others, whereby they evaluate, gossip, proselytize, bond, cooperate and control. Each person, working his way back and forth through his social network, almost continuously reviews past experiences while imagining the consequences of future scenarios.
A second diagnostic hereditary peculiarity of human behavior is the overpowering instinctual urge to belong to groups in the first place. To be kept in solitude is to be kept in pain, and put on the road to madness. A person’s membership in his group — his tribe — is a large part of his identity. It also confers upon him to some degree or other a sense of superiority. When psychologists selected teams at random from a population of volunteers to compete in simple games, members of each team soon came to think of members of other teams as less able and trustworthy, even when the participants knew they had been selected at random.
All things being equal (fortunately things are seldom equal, not exactly), people prefer to be with others who look like them, speak the same dialect, and hold the same beliefs An amplification of this evidently inborn predisposition leads with frightening ease to racism and religious bigotry.
It might be supposed that the human condition is so distinctive and came so late in the history of life on Earth as to suggest the hand of a divine creator. Yet in a critical sense the human achievement was not unique at all. Biologists have identified about two dozen evolutionary lines in the modern world fauna that attained advanced social life based on some degree of altruistic division of labor. Most arose in the insects. Several were independent origins, in marine shrimp, and three appeared among the mammals, that is, in two African mole rats, and us. All reached this level through the same narrow gateway: solitary individuals, or mated pairs, or small groups of individuals built nests and foraged from the nest for food with which they progressively raised their offspring to maturity.
Until about three million years ago the ancestors of Homo sapiens were mostly vegetarians, and they most likely wandered in groups from site to site where fruit, tubers, and other vegetable food could be harvested. Their brains were only slightly larger than those of modern chimpanzees. By no later than half a million years ago, however, groups of the ancestral species Homo erectus were maintaining campsites with controlled fire — the equivalent of nests — from which they foraged and returned with food, including a substantial portion of meat. Their brain size had increased to midsize, between that of chimpanzees and modern Homo sapiens. The trend appears to have begun one to two million years previously, when the earlier prehuman ancestor Homo habilis turned increasingly to meat in its diet. With groups crowded together at a single site, and an advantage added by cooperative nest building and hunting, social intelligence grew, along with the centers of memory and reasoning in the prefrontal cortex.
Probably at this point, during the habiline period, a conflict ensued between individual-level selection, with individuals competing with other individuals in the same group, versus group-level selection, with competition among groups. The latter force promoted altruism and cooperation among all the group members. It led to group-wide morality and a sense of conscience and honor. The competitor between the two forces can be succinctly expressed as follows: within groups selfish individuals beat altruistic individuals, but groups of altruists beat groups of selfish individuals. Or, risking oversimplification, individual selection promoted sin, while group selection promoted virtue.
So it appeared that humans are forever conflicted by their prehistory of multilevel selection. They are suspended in unstable and constantly changing locations between the two extreme forces that created us. We are unlikely to yield completely to either force as an ideal solution to our social and political turmoil. To yield completely to the instinctual urgings born from individual selection would dissolve society. To surrender to the urgings from group selection would turn us into angelic robots — students of insects call them ants.
The eternal conflict is not God’s test of humanity. It is not a machination of Satan. It is just the way things worked out. It might be the only way in the entire universe that human-level intelligence and social organization can evolve. We will find a way eventually to live with our inborn turmoil, and perhaps find pleasure in viewing it as a primary source of our creativity.

Edward O. Wilson

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Steven Pinker

The False Allure of Group Selection

6/18/12

I am often asked whether I agree with the new group selectionists, and the questioners are always surprised when I say I do not. After all, group selection sounds like a reasonable extension of evolutionary theory and a plausible explanation of the social nature of humans. Also, the group selectionists tend to declare victory, and write as if their theory has already superseded a narrow, reductionist dogma that selection acts only at the level of genes. In this essay, I’ll explain why I think that this reasonableness is an illusion. The more carefully you think about group selection, the less sense it makes, and the more poorly it fits the facts of human psychology and history.

STEVEN PINKER REPLIES 

Group selection has become a scientific dust bunny, a hairy blob in which anything having to do with “groups” clings to anything having to do with “selection.” The problem with scientific dust bunnies is not just that they sow confusion; … the apparent plausibility of one restricted version of “group selection” often bleeds outwards to a motley collection of other, long-discredited versions. The problem is that it also obfuscates evolutionary theory by blurring genes, individuals, and groups as equivalent levels in a hierarchy of selectional units; … this is not how natural selection, analyzed as a mechanistic process, really works. Most importantly, it has placed blinkers on psychological understanding by seducing many people into simply equating morality and culture with group selection, oblivious to alternatives that are theoretically deeper and empirically more realistic.

Human beings live in groups, are affected by the fortunes of their groups, and sometimes make sacrifices that benefit their groups. Does this mean that the human brain has been shaped by natural selection to promote the welfare of the group in competition with other groups, even when it damages the welfare of the person and his or her kin? If so, does the theory of natural selection have to be revamped to designate “groups” as units of selection, analogous to the role played in the theory by genes?

Several scientists whom I greatly respect have said so in prominent places. And they have gone on to use the theory of group selection to make eye-opening claims about the human condition.  They have claimed that human morality, particularly our willingness to engage in acts of altruism, can be explained as an adaptation to group-against-group competition. As E. O. Wilson explains, “In a group, selfish individuals beat altruistic individuals. But groups of altruistic individuals beat groups of selfish individuals.”

They have proposed that group selection can explain the mystery of religion, because a shared belief in supernatural beings can foster group cohesion. They suggest that evolution has equipped humans to solve tragedies of the commons (also known as collective action dilemmas and public goods games), in which actions that benefit the individual may harm the community; familiar examples include overfishing, highway congestion, tax evasion, and carbon emissions. And they have drawn normative moral and political conclusions from these scientific beliefs, such as that we should recognize the wisdom behind conservative values, like religiosity, patriotism, and puritanism, and that we should valorize a communitarian loyalty and sacrifice for the good of the group over an every-man-for-himself individualism.

I am often asked whether I agree with the new group selectionists, and the questioners are always surprised when I say I do not. After all, group selection sounds like a reasonable extension of evolutionary theory and a plausible explanation of the social nature of humans. Also, the group selectionists tend to declare victory, and write as if their theory has already superseded a narrow, reductionist dogma that selection acts only at the level of genes. In this essay, I’ll explain why I think that this reasonableness is an illusion. The more carefully you think about group selection, the less sense it makes, and the more poorly it fits the facts of human psychology and history.

Why does this matter? I’ll try to show that it has everything to do with our best scientific understanding of the evolution of life and the evolution of human nature. And though I won’t take up the various moral and political colorings of the debate here (I have discussed them elsewhere), it ultimately matters for understanding how best to deal with the collective action problems facing our species.

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The first big problem with group selection is that the term itself sows so much confusion. People invoke it to refer to many distinct phenomena, so casual users may literally not know what they are talking about. I have seen “group selection” used as a loose synonym for the evolution of organisms that live in groups, and for any competition among groups, such as human warfare. Sometimes the term is needlessly used to refer to an individual trait that happens to be shared by the members of a group….To use the term in these senses is positively confusing….

In this essay I’ll concentrate on the sense of “group selection” as a version of natural selection which acts on groups in the same way that it acts on individual organisms, namely, to maximize their inclusive fitness … Modern advocates of group selection don’t deny that selection acts on individual organisms; they only wish to add that it acts on higher-level aggregates, particularly groups of organisms, as well. For this reason, the theory is often called “multilevel selection” rather than “group selection.”….

1. Group selection as an explanation of the traits of groups.

First I’ll examine the idea that group selection is a viable explanation of the traits of human groups such as tribes, religions, cultures, and nations….

The theory of natural selection applies most readily to genes because they have the right stuff to drive selection, namely making high-fidelity copies of themselves. Granted, it’s often convenient to speak about selection at the level of individuals, because it’s the fate of individuals (and their kin) in the world of cause and effect which determines the fate of their genes. Nonetheless, it’s the genes themselves that are replicated over generations and are thus the targets of selection and the ultimate beneficiaries of adaptations….

Now, no one “owns” the concept of natural selection, nor can anyone police the use of the term. But its explanatory power, it seems to me, is so distinctive and important that it should not be diluted by metaphorical, poetic, fuzzy, or allusive extensions that only serve to obscure how profound the genuine version of the mechanism really is….

What about groups? Natural selection could legitimately apply to groups if they met certain conditions: the groups made copies of themselves by budding or fissioning, the descendant groups faithfully reproduced traits of the parent group (which cannot be reduced to the traits of their individual members), except for mutations that were blind to their costs and benefits to the group; and groups competed with one another for representation in a meta-population of groups. But everyone agrees that this is not what happens in so-called “group selection.” In every case I’ve seen, the three components that make natural selection so indispensable are absent.

(a) The criterion of success is not the number of copies in a finite population (in this case, the meta-population of groups), but some analogue of success like size, influence, wealth, power, longevity, territory, or preeminence. (For example) …monotheistic religions having more people, territory, wealth, might, and influence. These are impressive to a human observer, but they are not what selection, literally interpreted, brings about.

(b) The mutations are not random. Conquerors, leaders, elites, visionaries, social entrepreneurs, and other innovators use their highly nonrandom brains to figure out tactics and institutions and norms and beliefs that are intelligently designed in response to a felt need (for example, to get their group to predominate over their rivals).

(c) The “success” applies to the entity itself, not to an entity at the end of a chain of descendants. It was the Roman Empire that took over most of the ancient world, not a group that splintered off from a group that splintered off from a group that splintered off from the Roman Empire, each baby Roman Empire very much like the parent Roman Empire except for a few random alterations, and the branch of progeny empires eventually outnumbering the others.

On top of these differences, most of the groupwide traits that group selectionists try to explain are cultural rather than genetic….they are traits that are propagated culturally, such as religious beliefs, social norms, and forms of political organization….

What all this means is that so-called group selection, as it is invoked by many of its advocates, is not a precise implementation of the theory of natural selection,… what does “natural selection” add to the historian’s commonplace that some groups have traits that cause them to grow more populous, or wealthier, or more powerful, or to conquer more territory, than others?

2. Group selection as an explanation of the traits of individuals.

Let’s now turn to the traits of individuals. Is group selection necessary to explain the evolution of psychological traits adapted to group living such as tribalism, bravery, self-sacrifice, xenophobia, religion, empathy, and moralistic emotions? …

The reproductive success of humans undoubtedly depends in part on the fate of their groups.  If a group is annihilated, all the people in it, together with their genes, are annihilated…. But if a person has innate traits that encourage him to contribute to the group’s welfare and as a result contribute to his own welfare, group selection is unnecessary; individual selection in the context of group living is adequate….

It’s only when humans display traits that are disadvantageous to themselves while benefiting their group that group selection might have something to add.

And this brings us to the familiar problem which led most evolutionary biologists to reject the idea of group selection in the 1960s…. any genetic tendency to risk life and limb that results in a net decrease in individual inclusive fitness will be relentlessly selected against. A new mutation with this effect would not come to predominate in the population, and even if it did, it would be driven out by any immigrant or mutant that favored itself at the expense of the group.

Let’s take the concrete example of collective aggression. Often the benefits to the self and to the group may coincide. A warrior may scare off a party of attackers and save the lives of his fellow villagers together with the lives of himself and his family. In other cases the benefits may diverge…. We should expect selection to favor traits that maximize the individual’s expected reproductive output …. What we don’t expect to see is the evolution of an innate tendency among individuals to predictably sacrifice their expected interests for the interests of the group—to cheerfully volunteer to serve as a galley slave, a human shield, or cannon fodder.   … If one is the unlucky victim of such manipulation or coercion by others, there’s no need to call it altruism and search for an evolutionary explanation, any more than we need to explain the “altruism” of a prey animal who benefits a predator by blundering into its sights….

To be sure, if we go back to group selection as an explanation of group traits, particularly cultural ones, then it’s easy to see how a group that successfully coerced or manipulated a renewable supply of its own members to launch suicide attacks might expand relative to other groups. …

3. Do Humans in Fact Have Adaptations that Benefit the Group at the Expense of the Self?

The recent surge of interest in group selection has been motivated by two empirical phenomena. One is eusociality in insect taxa such as bees, ants, and termites, whose worker or soldier castes forgo their own reproduction and may sacrifice their lives to benefit their fellows, as when a bee dies when stinging an invader. E. O. Wilson notes that a self-sacrificing insect benefits the colony, and concludes that eusociality must be explained by selection among colonies. But most other biologists point out that the sacrificer benefits the queen (her sister or mother), who founds a new colony when she reproduces, so the simplest explanation of eusociality is that the genes promoting self-sacrifice were selected because they benefited copies of themselves inside the queen….

The other phenomenon is the existence of altruism and self-sacrifice among humans, such as martyrdom in warfare, costly punishment of free riders, and generosity toward strangers. Group selectionists often analogize self-sacrifice among humans to eusociality in insects, and explain both by group selection. In The Social Conquest of Earth, a book whose title alludes to the evolutionary success of humans and social insects, Wilson writes, (p. 56): “An unavoidable and perpetual war exists between honor, virtue, and duty, the products of group selection, on one side, and selfishness, cowardice, and hypocrisy, the products of individual selection, on the other side.” …

Another problem with the bundling of human altruism, insect eusociality, and group selection is that insect eusociality itself is not, according to most biologists other than Wilson, explicable by group selection. …

So for the time being we can ask, is human psychology really similar to the psychology of bees? When a bee suicidally stings an invader, presumably she does so as a primary motive, as natural as feeding on nectar or seeking a comfortable temperature. But do humans instinctively volunteer to blow themselves up or advance into machine-gun fire, as they would if they had been selected with group-beneficial adaptations? …

The huge literature on the evolution of cooperation in humans has done quite well by applying the two gene-level explanations for altruism from evolutionary biology, nepotism and reciprocity, each with a few twists entailed by the complexity of human cognition.

Nepotistic altruism in humans consists of feelings of warmth, solidarity, and tolerance toward those who are likely to be one’s kin…. A vast amount of human altruism can be explained in this way….The other classic form of altruism is reciprocity: initiating and maintaining relationships in which two agents trade favors, each benefiting the other as long as each protects himself from being exploited…

Group selection, in contrast, fails to predict that human altruism should be driven by moralistic emotions and reputation management, since these may benefit of individuals who inflate their reputations relative to their actual contributions and thus subtract from the welfare of the group. Nor is there any reason to believe that ants, bees, or termites have moralistic emotions such as sympathy, anger, and gratitude, or a motive to monitor the reputations of other bees or manage their own reputations. Group welfare would seem to work according to the rule “From each according to his ability, to each according to his need.” Ironically, Wilson himself, before he came out as a group selectionist, rejected the idea that human altruism could be explained by going to the ants, and delivered this verdict on the Marxist maxim: “Wonderful theory; wrong species.” Haidt, too, until recently was content to explain the moral emotions with standard theories of nepotistic and reciprocal altruism….

Finally, let’s turn to the role of altruism in the history of group-against-group conflict. Many group selectionists assume that human armed conflict has been a crucible for the evolution of self-sacrifice, like those in insect soldier castes. They write as if suicide missions, kamikaze attacks, charges into the jaws of death, and other kinds of voluntary martyrdom have long been the norm in human conflict. My reading of the history of organized violence is that this is very far from the case.

In tribal warfare among non-state societies, men do not regularly take on high lethal risks for the good of the group. Their pitched battles are noisy spectacles with few casualties, while the real combat is done in sneaky raids and ambushes in which the attackers assume the minimum risks to themselves. When attacks do involve lethal risks, men are apt to desert, stay in the rear, and find excuses to avoid fighting, unless they are mercilessly shamed or physically punished for such cowardice….

What about early states? States and empires are the epitome of large-scale coordinated behavior and are often touted as examples of naturally selected groups. Yet the first complex states depended not on spontaneous cooperation but on brutal coercion. They regularly engaged in slavery, human sacrifice, sadistic punishments for victimless crimes, despotic leadership in which kings and emperors could kill with impunity, and the accumulation of large harems, with the mathematically necessity that large number of men were deprived of wives and families….

To be sure, the annals of war contain tales of true heroism—the proverbial soldier falling on the live grenade to save his brothers in arms. But note the metaphor. Studies of the mindset of soldierly duty shows that the psychology is one of fictive kinship and reciprocal obligation within a small coalition of individual men, far more than loyalty to the superordinate group they are nominally fighting for. The writer William Manchester, reminiscing about his service as a Marine in World War II, wrote of his platoonmates, “Those men on the line were my family, my home. … They had never let me down, and I couldn’t do it to them. . . . Men, I now knew, do not fight for flag or country, for the Marine Corps or glory of any other abstraction. They fight for one another.”…

And once again, it won’t work to switch levels and say that group selection is really acting on the norms and institutions of successful states. The problem is that this adds nothing to the conventional historian’s account in which societies with large tax bases, strong governments, seductive ideologies, and effective military forces expanded at the expense of their neighbors. That’s just ordinary causation, enabled by the fruits of human ingenuity, experience, and communication. The truly Darwinian mechanisms of high-fidelity replication, blind mutation, differential contribution of descendants to a population, and iteration over multiple generations have no convincing analogue.

4. A Summary of the Trouble with Group Selection

The idea of Group Selection has a superficial appeal because humans are indisputably adapted to group living and because some groups are indisputably larger, longer-lived, and more influential than others. This makes it easy to conclude that properties of human groups, or properties of the human mind, have been shaped by a process that is akin to natural selection acting on genes. …

None of this prevents us from seeking to understand the evolution of social and moral intuitions, nor the dynamics of populations and networks which turn individual psychology into large-scale societal and historical phenomena. It’s just that the notion of “group selection” is far more likely to confuse than to enlighten—especially as we try to understand the ideas and institutions that human cognition has devised to make up for the shortcomings of our evolved adaptations to group living.

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STEVEN PINKER is a Harvard College Professor and Johnstone Family Professor of Psychology; Harvard University. Author, The Better Angels Of Our Nature: How Violence Has Declined, The Language Instinct, and How the Mind Works.

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Natural selection

is a special explanatory concept in the sciences, worthy, in my view, of Daniel Dennett’s designation as “the best idea that anyone ever had.” That’s because it explains one of the greatest mysteries in science, the illusion of design in the natural world. The core of natural selection is that when replicators arise and make copies of themselves, (1) their numbers will tend, under ideal conditions, to increase exponentially; (2) they will necessarily compete for finite resources; (3) some will undergo random copying errors (“random” in the sense that they do not anticipate their effects in the current environment); and (4) whichever copying errors happen to increase the rate of replication will accumulate in a lineage and predominate in the population. After many generations of replication, the replicators will show the appearance of design for effective replication, while in reality they have just accumulated the copying errors that had successful replication as their effect. Steven Pinker