The Price of Altruism (42 page)

T
wo things,” the philosopher Immanuel Kant wrote, “fill the mind with ever new and increasing admiration and awe, the oftener and more steadily we reflect on them: the starry heavens above and the moral law within.”
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And, to be sure, from Darwin to Allee, Kropotkin to Fisher, Emerson to Haldane to Wynne-Edwards, the mystery of altruism, considered the highest form of morality, was attacked from all possible directions. Where did altruism come from: Could it have been borne by the invisible hand of natural selection working directly on genes, on individuals, perhaps, on communities, on groups? Each had a hunch, and each had an answer. Still in awe, still in admiration, no one came up with an entirely convincing solution.

Then came George C. Williams. “Group-related adaptations do not, in fact, exist,” he ordained; while possible in principle, genes don’t evolve via between-group selection.
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Soon the entire world was let in on the secret: Using Williams’s logic and building on Hamilton’s inclusive fitness, Trivers’s reciprocation, and Maynard Smith and George’s ESS, a Kenyan-born Oxford biologist with a soft voice and a sharp rapier fashioned a gospel. Appearances to the contrary, it was genes running the show, Richard Dawkins explained in
The Selfish Gene
in 1976, a book that soon became one of the century’s greatest best sellers. In the final reckoning individuals are just aggregations of elements that are shuffled and disbanded when the sexual gametes are made. It’s the genes, not the soma, that persevere in evolution; DNA, not the body, which by sheer power of replicatory fidelity lives to fight another day. Even though, Huxley-style, Dawkins explicitly stated that humans were the only creatures in the world who could rebel against the tyranny of their selfish replicators, to many his message felt unusually deflating: When it comes to natural selection the best individuals could call themselves was “vehicles.”
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But despite immediate criticism
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and however weirdly counterintuitive, it was a robust theory: As biology marched ahead it seemed to unify a plethora of phenomena. Whether animals aid their kin (ants and wolves who help their sisters breed) or nonrelatives (vampire bats who share blood, mouth to mouth, at the end of a night of prey with members of the colony who were less successful in the hunt); whether they abandon their eggs (sharks and skates and stingrays) or goslings (eagle owls and leopard-faced vultures) or sacrifice themselves for the next generation (male praying mantises serve their heads during coitus to their avaricious ladies); whether they come together as a group (Siberian steeds forming rings against predators) or aid themselves at the expense of their hosts (from the common cold bug to proliferating cancers)—all living things are acting in the interest of their true masters: a cabal of genes whose sole imperative is replication. Volition and mind and “free will” notwithstanding, evolution fashioned genes that do whatever it takes to survive.

If Williams, aided by Dawkins, helped get rid of groups, kin selection had acted as a handmaiden. Scaling the eighties and nineties into the twenty-first century, family relatedness threw massive ropes down from Mount Modern-Evolutionary-Biology for others to safely climb. Haldane’s mythological drunken insight and Hamilton’s resulting rule, it transpires, hold up incredibly well in the face of winds, falling rocks, and negative slopes. From the naked African mole rat, the mammalian equivalent of the termite, sometimes called the “saber-toothed sausage,” which forsakes procreation in order to help its chosen monarch, to the carnivorous spadefoot toad tadpole, which can actually “taste” relatedness and therefore spits out cousins and brothers—but not strangers—that find themselves in his mouth, relatedness has proven to be a robust predictor of altruistic behavior. Even cuckoos have figured out this metric: They take advantage of other birds’ familial instincts by laying their eggs in complete strangers’ nests, allowing the tricked parents to shoulder the burden of parenthood.
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Beginning in the seventies, hundreds of biologists, ecologists, and evolutionary modelers have used Hamiltonian logic to make sense of many dramas of love and deception. With few exceptions, the general rule holds: The closer the kin, the greater the benevolence.
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Two very different examples help to show just how far kin selection has captured the imagination:

Moving through soil by extending its pseudopods, most of the time the cellular slime mold,
Dictyostelium discoideum
, is a loner. Usually it engulfs and eats bacteria, but when times are rough and bacteria are scarce, something amazing happens: The starving amoebas secrete a chemical, cAMP, which attracts the others along a concentration gradient, until chains of tens of thousands of them merge into a mound. Soon the mound elongates into a slug that begins to crawl, as one multicellular body, across the forest floor. When it reaches a place with some heat and light it stops, and the amoebas that formed the front 20 percent of the body arrange themselves into a stalk, laying down tough cells of cellulose, just like plants, to make it nice and hardy. Then the remaining 80 percent climb up the stalk. When they reach the top they reorganize themselves into spores, forming a round glistening orb. It is this 80 percent that will stand a chance to live another day, sticking perhaps to the wings or legs of some insect, or otherwise being taken by the wind. The 20 percent that formed the stalk, on the other hand, will have sacrificed themselves altruistically for all the rest.
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This is incredible, but what was discovered next is even more fascinating. In the wild most fruiting bodies form from a single clone: All the amoebas coming together to make the slug are virtually genetically identical. But when the husband-and-wife team Joan Strassman and David Queller mixed amoebas from different clones they uncovered the following: Able to recognize one another, members of one clone did their best to stick together at the backside of the slug. When the stalk was made, it was primarily they, and not the others, who shimmied up to become hopeful spores.
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If amoeba can recognize and aid kin, so too, of course, can humans; this shouldn’t be all that surprising. What is surprising is that studies have shown that stepchildren are not only much less likely to be invested in than biological children, but also much more likely to be abused. Surprising, that is, if your names aren’t Martin Daly and Margo Wilson.
This
husband-and-wife team has taken kin-selection logic to its end: Just like the slime mold, they claim, and the spitting toad and the cuckoo, humans are simply following Hamilton’s rule.
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But if genetic relatedness was a handmaiden to the gene’s-eye point of view, von Neumann games also proved a useful mountaineering partner. Soon its ropes, too, were being climbed by many a follower. The point of departure was George and Maynard Smith. Bolstered in
The Selfish Gene
, the concept of the ESS soon invaded the study of animal behavior. George and John, it transpired, had made an error in their paper: Retaliator, after all, was not an ESS. Since Dove did equally as well in a population of Retaliators, it could slowly drift into the population. When that happened, the true ESS would become a mixture of “Hawks” and “Bullies.”
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George, perhaps, might not have been glad to hear about it, nor to know that his “Mouse” had once again become a “Dove.”
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But considering that within a decade the application of game theory to evolution had revolutionized the field, perhaps he might have been assuaged nonetheless.

Once more, two illustrations from the many serve to make the point. Male dung flies, it transpires, are aptly named: Like fierce elephant seals or bucking red deer, they too defend their territory, even if in their case this is nothing but a patch of smelly excrement. The reason they do so is that females lay their eggs on the dung, and the fresher (and thus smellier) the patch, the more attractive it is to them. Having arrived earlier, males fight over the best patches; he who secures the most attractive dropping will win the right to mate with the female as she deposits her eggs. The question is: For how long should a male fly defend a patch of fresh shit before moving on to another? After all, the drier and crustier it becomes, the less chance that a female will choose to land on it. Clearly, just as in a von Neumann game, the answer depends on the actions of the other male flies. It turns out that, fashioning the minute fly a strategist, an optimal ESS can be worked out. On paper it is forty-one minutes, and incredibly, in nature it’s just a few minutes away.
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But if an ESS is good for flies, once again it is not too good for humans. In fact, game theory analyses of animal, and even plant and bacteria, behavior have been so successful that the modifications made specifically to fit evolutionary problems are now being retranslated back into economics. If neoclassical economic theory à la Milton Friedman assumed perfectly rational actors, it has since become clear that this is not really so: Risk aversion, status seeking, myopia, and other inbuilt cognitive biases are rampant in humans, and economic models of decision making need to take them into account. Introducing evolution-style games that assume minimal rationality, but whose dynamic depends on mutation, selection, and learning instead, has therefore become popular in economic theory. As an increasing number of theorists have found, this approach is helpful in figuring out problems like why firms don’t always act to maximize their profits, or whether in a given competitive market investors should be aggressive or lazy. Darwin owed a debt to Malthus, and his followers are paying it back.
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Alongside kin selection and game theory, Trivers’s reciprocal altruism has also lowered a rope from Mount Modern-Evolutionary-Biology. One of the first to climb it, in fact, was Bill Hamilton himself. Trivers had sent him a draft of his 1971 paper, and, though Hamilton found the math flawed, he encouraged the young American to continue. It turned out that the two animal examples provided in that paper were not, in fact, good examples of reciprocal altruism: Cleaning fish not being swallowed by their larger hosts when danger came around was later repaid by hosts returning to the same cleaners, as were warning cries made by particular birds when predators were spotted lurking. These were more accurately instances of “return-effect” altruism rather than reciprocal altruism because the return benefit didn’t come from the second party’s
choice
to reciprocate but rather for other reasons. But despite the semantic imprecision and the weak math, it didn’t really matter; Trivers had thrown down the rope. A decade later, together with the American political scientist Richard Axelrod, Hamilton proved mathematically that, alongside perpetual defection, the strategy of tit for tat is a Nash equilibrium: Through iterated encounters natural selection would favor social behaviors that exacted a fitness cost in the short run. Reciprocal altruism had been welded to the prisoner’s dilemma. And while perpetual isolation was always an option, the rule of cooperation was simple enough for a bacterium. “The benefits of life are disproportionately available to cooperative creatures,” Axelrod and Hamilton began, and Trivers, for one, thought it of “biblical proportions.” “My heart soared,” he wrote to Bill after sitting down one night with classical music to read the paper.
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Soon Mount Modern-Evolutionary-Biology was crowded with others climbing up the reciprocal altruism rope. The prisoner’s dilemma, these researchers found, was too simplified a version of natural interactions. But allowing for the inclusion of punishment and forgiveness, delicate cheating, observer effects (when a third party looking on has an impact on the two-person game—something called “indirect reciprocity”), and many other subtleties eventually inched the fit between nature and such models closer together. As the years progress the laws of cooperation gain steadily: Theory and observation alike place them firmly as a powerful motor in the evolution of altruistic behavior.
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Pure direct reciprocal altruism between nonkin in nature, it must be said, has proved something of a rarity. For one thing the altruistic helpers might actually be related more often than Trivers and others suspected, rendering “reciprocal altruism” nothing but a version of Hamiltonian kin selection. Another problem seems to be that behaviors that were once interpreted as pure-cost assistance (baboons grooming each others’ backs for fleas, for example), may actually just be a form of mutualism (the baboons gain valuable nourishment from eating their friends’ fleas). Yet another impediment to the “you-scratch-my-back-I’ll-scratch-yours” theory comes courtesy of Oscar Wilde. “I can resist everything except temptation,” he quipped in
Lady Windermere’s Fan
, and most animals, experiments show, are not all that different. Immediate gratification is the custom of even the most intelligent and social of mammals, a thorn in the side of establishing the courtly conventions that serve as requisites for social restraint.

Finally, a theory called “the handicap principle,” espoused by the Israeli zoologist Amotz Zahavi, argues that animals that perform ostensible acts of sacrifice do so to prove that they are worthy of reciprocation. Thus, when a gazelle spots a lion lurking in the grass and begins to jump up and down in the air (a behavior called “stotting”), she is advertising to her friends that she is “willing” to pay a price for being part of the group. The problem with this solution to reciprocation’s underbelly of deceit is that it is very difficult to falsify. What may seem like a selfless warning to her friends (or at the very least an act expecting reciprocation) might actually be a signal to the lion that he should focus his pursuit on a member of the troop less athletic and therefore more likely to end up on his palate. Likewise, a male peacock sporting a gigantic (and costly) colorful tail, or a bull elk showing off its large rack of antlers, may be signaling to potential mates that they need not look any further, that Numero Uno is stronger precisely because he carries a hindrance that would handicap a lesser fellow.
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