David Brooks, New York Times columnist and author of The Social Animal, has never met an evolutionary psychology argument he didn’t like. I haven’t read his book, but I did read a long excerpt in The New Yorker and found it credulous, tedious, and lame. P.Z. Myers, who reviewed the book, had the same opinion. So did philosopher Thomas Nagel, who, reviewing the book in the New York Times, pretty much ripped it apart, noting that “Brooks seems willing to take seriously any claim by a cognitive scientist, however idiotic. . ” (It’s quite unusual for the Times to publish bad reviews of books by their own columnists.)
In yesterday’s New York Times, Brooks writes about recent scientific “advances” in the understanding of human altruism. And he signs on to the idea that altruism evolved by group selection.
I disagree, and see Brooks as ignorant about the true scientific issues. If true altruism (which I define here) is indeed a trait that’s deleterious to an individual’s reproductive fitness, then it could, as Brooks envisions, evolve only by the differential survival and reproduction of groups.
That form of evolution would work like this: although genes for altruistic behavior would be constantly weeded out of populations (for altruists, by definition, sacrifice their own genetic heritage for others), those genes might survive if groups that contained higher proportions of altruists were the groups that persisted, giving rise to descendant groups more often than groups lacking altruists. (The idea here is that groups without altruists wouldn’t flourish very well.) That’s group selection, and it’s how Brooks sees altruism as evolving:
In his book, “The Righteous Mind,” to be published early next year, Jonathan Haidt joins Edward O. Wilson, David Sloan Wilson, and others who argue that natural selection takes place not only when individuals compete with other individuals, but also when groups compete with other groups. Both competitions are examples of the survival of the fittest, but when groups compete, it’s the cohesive, cooperative, internally altruistic groups that win and pass on their genes. The idea of “group selection” was heresy a few years ago, but there is momentum behind it now.
Let’s be clear about what biologists really know about group selection and altruism. If true human altruism has a genetic basis, it is individually disadvantageous and could have evolved only by differential propagation of groups. That’s very unlikely, since it requires that the rate at which altruist-containing groups reproduce themselves must be high enough to counteract the substantial rate at which altruism genes disappear within groups. It’s unlikely because groups reproduce much less often than do individuals! Further, once a group consists entirely of altruists, any non-altruistic genes would rapidly invade it, as their carriers reap the benefits of altruism without sacrificing their reproduction.
Now if we’re talking about apparent altruism, in which individuals appear to sacrifice their reproductive interests but actually reap hidden genetic benefits, then we don’t need group selection to explain it. As I’ve written in a longer post on this topic, kin selection (“inclusive fitness”) can do it, as can simple individual selection based on reciprocity or, simply. selection for the advantages of cooperation, as in hunting lions.
Humans, after all, evolved in small social groups, which provide the ideal environment for the evolution of “reciprocal altruism” (“I scratch your back and you scratch mine”). That kind of altruism, which isn’t “true” altruism in the sense of hurting one’s reproductive prospects, evolves most readily in small groups where individuals know and recognize each other, and have a big brain for remembering and reciprocating good deeds. Living in groups, particularly of kin, facilitates the evolution of apparent altruism, but that is not group selection since it doesn’t require differential propagation of groups. Genes that are selected in groups based on relatedness or individual advantage will spread throughout a species without requiring differential reproduction of groups. That is, selection occurs in the context of groups, but doesn’t occur through selection among groups.
What do we know about human altruism? First of all, we don’t know whether true altruism, in which individuals behave in ways that help others by hurting their own reproductive prospects (firemen are one example), has any genetic basis in human society. True altruism like that isn’t known in any other species, and I suspect that, to the extent it occurs in ours, it’s an epiphenomenon: a byproduct of our general social cooperativeness. As far as whether we are genetically cooperative (rather than truly altruistic), that seems quite likely, but it doesn’t require group selection. It requires selection that occurred in groups, which is different. And we almost certainly have some behaviors that evolved by kin selection, parental care being the most obvious.
So Brooks misrepresents the views of biologists in his piece. There really isn’t much momentum in the evolution community behind the idea of “group selection.” There is increasing realization that selection can occur in groups, that being in groups can affect how selection operates on genes, and that there can be group effects (“multilevel selection”) that influence the evolution of genes. But there is no general feeling that “group selection” is widespread or important. And there is no widespread agreement that true altruism, or even apparent altruism, evolved by the differential propagation of groups.
In short, we know nothing about the evolution of true human altruism except that it probably didn’t evolve. And we don’t know much more about the evolution of human cooperation. It almost certainly has a genetic basis—we’re social animals, after all—but we’re ignorant about the form of natural selection that favored such cooperation, and about the social and environmental circumstances that promoted that selection.
Brooks makes one more biological error, asserting that the evolution of cooperation necessarily entails evolved morality.
But the big upshot is this: For decades, people tried to devise a rigorous “scientific” system to analyze behavior that would be divorced from morality. But if cooperation permeates our nature, then so does morality, and there is no escaping ethics, emotion and religion in our quest to understand who we are and how we got this way.
Cooperation also permeates the nature of honeybees, termites, naked mole rats, and lions, but they don’t have morality. Morality is the result of having a big brain that, in a social species, can remember other individuals and make calculations about their intentions. Whether that “result” is genetic, so that our moral feelings are encoded in our DNA, or simply an epiphenomenon, in which we’re taught rules that enable us to function, is an open question. I suspect that some of it is genetic, but we just don’t know.