The False Allure of Group Selection

– Steven Pinker 2012.6.18

1. Defining “group selection”
   1. As George Williams noted,“a fleet herd of deer” is really just a herd of fleet deer
   2. 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 (alternatively, which acts on groups in the same way it acts on genes, namely to increase the number of copies that appear in the next generation)
   3. “Multilevel selection”: I don’t think it makes sense to conceive of groups of organisms (in particular, human societies) as sitting at the top of a fractal hierarchy with genes at the bottom, with natural selection applying to each level in parallel ways.
2. What is and isn’t natural selection: Darwinian mechanisms of high-fidelity replication, blind mutation, differential contribution of descendants to a population, and iteration over multiple generations
   1. 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.
   2. Some things last longer or do better in competition than others because they have traits that help them last longer or compete more effectively. But unless the traits arose from multiple iterations of copying of random errors in a finite pool of replicators, the theory of natural selection adds nothing to ordinary cause and effect.
3. Group selection as an explanation of the traits of groups
   1. Natural selection could legitimately apply to groups if they met certain conditions:
      1. the groups made copies of themselves by budding or fissioning
      2. the descendant groups faithfully reproduced traits of the parent group (which cannot be reduced to the traits of their individual members)
      3. 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.
   2. In every case I’ve seen, the three components that make natural selection so indispensable are absent.
      1. 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
      2. The mutations are not random
      3. The “success” applies to the entity itself, not to an entity at the end of a chain of descendants
   3. On top of these differences, most of the group-wide traits that group selectionists try to explain are cultural rather than genetic.
4. Group selection as an explanation of the traits of individuals
   1. 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.
   2. It’s only when humans display traits that are disadvantageous to themselves while benefiting their group that group selection might have something to add.
      1. We should expect selection to favor traits that maximize the individual’s expected reproductive output, given these tradeoffs
      2. 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
      3. What could evolve, instead, is a tendency to manipulate others to become suicide attackers, and more generally, to promulgate norms of morality and self-sacrifice that one intends to apply in full force to everyone in the group but oneself
         1. 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
   3. Thus we have a nice set of competing empirical predictions for any examples of group-benefiting self-sacrifice we do observe in humans
      1. If humans were selected to benefit their groups at the expense of themselves, then self-sacrificial acts should be deliberate, spontaneous, and uncompensated, just like other adaptations such as libido, a sweet tooth, or parental love
      2. But if humans were selected to benefit themselves and their kin in the context of group living, then any guaranteed self-sacrifice should be a product of manipulation by others, such as enslavement, conscription, external incentives, or psychological manipulation.
      3. 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? My reading of the study of cooperation by psychologists and anthropologists, and of the study of group competition by historians and political scientists, suggest that in fact human are nothing like bees.
   4. Gene-level explanations for altruism
      1. Reciprocity
         1. discriminate reciprocators from exploiters only by direct personal experience, but can also ask around and find out their reputation for reciprocating with or exploiting others
         2. creates incentives to establish and exaggerate one’s reputation and to attempt to see through such exaggerations in others
         3. One way to credibly establish one’s reputation as an altruist in the probing eyes of skeptics to be an altruist, that is, to commit oneself to altruism (and, indirectly, its potential returns in the long run, at the expense of personal sacrifices in the short run)
      2. Nepotism
         1. Compared to the way people treat non-relatives, they are far more likely to feed their relatives, nurture them, do them favors, live near them, take risks to protect them, avoid hurting them, back away from fights with them, donate organs to them, and leave them inheritances.
         2. faux-families may be created by metaphors, simulacra of family experiences, myths of common descent or common flesh, and other illusions of kinship
5. Role of altruism in the history of group-against-group conflict
   1. In tribal warfare among non-state societies, 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
   2. 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
   3. The historically recent phenomenon of standing national armies was made possible by the ability of increasingly bureaucratized governments to impose conscription, indoctrination, and brutal discipline on their powerless young men…Once the illusion of quick victory was shattered, the soldiers were ordered into battle by callous commanders and goaded on by “file closers” (soldiers ordered to shoot any comrade who failed to advance) and by the threat of execution for desertion, carried out by the thousands. In no way did they act like soldier ants, willingly marching off to doom for the benefit of the group.
   4. 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, “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…They fight for one another.”
   5. Suicide attacks: generally recruited from the ranks of men with poor reproductive prospects, and they are attracted and egged on by some combination of peer pressure, kinship illusions, material and reputational incentives to blood relatives, and indoctrination into the theory of eternal rewards in an afterlife. These manipulations are necessary to overcome a strong inclination not to commit suicide for the benefit of the group.
   6. It’s more accurate to say that groups of individuals that are organized beat groups of selfish individuals. And effective organization for group conflict is more likely to consist of more powerful individuals incentivizing and manipulating the rest of their groups than of spontaneous individual self-sacrifice