The Price of Altruism (22 page)

Maynard Smith took a cool look at the data. Despite the vogue of population-explosion hysteria there was no need to get excited. Theoretically, though, if group selection worked, short of decreasing homosexuality and clearing up traffic jams, it could be an important mechanism in evolution.

He himself had been contemplating the phenomenon of aging. Why, for heaven’s sake, would evolution select for the degrading of the body: Wouldn’t it be better to be able to reproduce indefinitely? The nineteenth-century giant August Weismann had considered the conundrum and thought the answer lay with the collective: Evolution pushed individuals into old age to make room for the next generation—in the absence of unlimited resources this was surely the best solution for all.
²²

But Maynard Smith wasn’t convinced by the logic of the generous-hearted doddering for the good of the replenishing tribe. In the wild, animals hardly ever made it to old age; reproduction declines with survival, not necessarily aging, since the more time lived the greater the chances to die. If natural death rarely occurs in nature, selection couldn’t have produced the trait of aging. Perhaps this was a genetic story, then, rather than one of “group selection”: The very same genes that helped an organism’s fitness when young might with time contribute to aging, having sneaked past the watchful gaze of selection when they were being passed on to the next generation.
²³

This kind of “gene’s-eye” view of evolution he had inherited from Haldane, which was perhaps why the editors of the
Journal of Theoretical Biology
had sent him a paper by Bill Hamilton that had left two other reviewers completely baffled and perplexed.

Thanks to the unusual social life of the
Hymenoptera
, “The Genetical Evolution of Social Behaviour” introduced an original idea. For the better part of the century classical population geneticists had defined “fitness” as the measure of an organism’s reproductive success: The more off spring an organism sired, the greater its fitness. A corollary of this definition was that the persistence of any behavior or gene responsible for it which reduced an organism’s fitness would be difficult to explain: in time, as was her mandate, natural selection should see to its demise. But Hamilton now showed that if fitness were redefined to include the progeny of relatives rather than just one’s own, in many cases the Darwinian difficulty of explaining the evolution of altruistic behavior would simply disappear. The key was adopting a “gene’s eye” point of view, and the
Hymenoptera
showed precisely why.

In the ancient order—comprising sawflies, wasps, bees, and ants—female workers are more closely related to their sisters than to their offspring due to a genetic quirk in their sex-determining heredity called “haplodiploidy.” All females are born of eggs fertilized by sperm and are
diploid
(meaning that they possess a full compliment of chromosomes from both their mother and father), whereas all males are born of unfertilized eggs and are
haploid
(meaning that they have no father but rather only a single set of chromosomes from their mother). Since female sister workers share all their father’s genes and half their mother’s, their coefficient of relationship is
r
= 0.75, whereas since they pass only half their genes on to the next generation the relationship to their off spring is
r
= 0.5. Brothers and sisters, on the other hand, only share one common ancestor, their mother, and are therefore only half as related as normal siblings, with
r
= 0.25.

The implications were strangely illuminating. Lazy male drones were not moral slackers but genetic opportunists: They spent their time seeking to mate rather than work since their relatedness to off spring would be double their relatedness to any sisters they might oblige. Female workers, too, were shrewd genetic calculators. Neither shirkers of parenthood nor mindless toilers, farming the queen as a “sister-producing machine”
²⁴
served their interests more generously than did siring their own brood. Everything depended on perspective: From the point of view of the gene trying to make its way into the next generation, it made absolutely no difference in whose body it was being carried. In one stroke, a century after Darwin, “inclusive fitness” unveiled the mystery of the ants.
²⁵

But Hamilton didn’t stop there; the
Hymenoptera
, after all, were just an illustration. Trudging through pages of algebra he had come up with an elegant equation. It sounded almost economic: Every altruistic act—such as a rabbit thumping its legs to warn its friend of the presence of a predator, or a howler monkey doing the same with its call—would entail both a fitness cost to the altruist (the chance that he might attract the predator himself), and a fitness benefit to the receiver (the chance to live another day and produce more offspring). What Hamilton showed was that, for every social situation, if the benefit (B), devalued by the relatedness between the two (
r
), was greater than the cost (C), genes responsible for altruistic behavior could evolve. The greater the relatedness the greater chance for altruism. With the help of the mathematics of genes,
r
B > C formalized what Darwin and Huxley and Fisher and Haldane had all intuited: altruism was a family affair.

Boom!

Thrown to the ground, he took a moment to notice the blood soaking his shirt below the chest and oozing from his mangled hand. There was sawdust, and smoke, and the unmistakable bittersweet taste of gunpowder. He could hardly see through the haze and was growing woozy.
²⁶

William Donald Hamilton was born in the summer of 1936 on a small island in Egypt’s Nile to Bettina, a physician, and her husband, Archibald, a military engineer, both of them New Zealanders. After they discovered that army life was neither their inclination nor priority, they’d settled in a cottage on Badgers Mount, at the rural edge of the North Downs, County Kent, England. Bettina quit medicine to raise a family—there was his sister Mary and four more children on their way, and Archibald set up a bridge design business, gaining his growing family a steady income from the prefab steel Callender-Hamilton used by army tanks to gallop across ravines in World War II.

Archibald had taken away the rusty tins filled with explosive powder Bill unearthed in a rabbit burrow a few days earlier and stashed them in a shed. But it was too little to stave off his son’s curiosity. Now, just as he was clamping a powder-filled brass cartridge with a vise, it blew up. With his last ounces of strength, he dragged himself into the house and collapsed on the kitchen floor. He was twelve years old. There was shrapnel in his lungs, and the tips of three fingers were missing. He would live. Risky business was a Hamilton family trait.

“Oaklea,” named after Archibald’s old New Zealand dwelling, was a cramped home whose inhabitants were tinkering and practical, and “as far as possible, a self-supporting republic.” You wouldn’t find a plumber invited, nor a carpenter, a welder, or an electrician. Nor, for that matter, could you find a proper room; Bill usually slept on an army cot in the corner of the dining room, or, when the frosty winters gave way to the cool evening breezes of spring, in one of the many tool sheds surrounding the cottage. In a dry creek or beneath a large piece of birch bark or in a cozy burrow would do; sometimes he’d forget to come home at night from his lost-to-the-world natural explorations. Walking barefoot and oblivious down woodland paths “chasing clouded yellow butterflies through fields of red clover,” Bill was happiest among plants and insects. The Hamiltons were fiercely independent, highly spiritual, unsentimental people. Bettina had a keen interest in natural history, and clearly she’d passed it on to her son.
²⁷

But young Bill had inherited his father’s aptitude for math, too, even if he thought he was no good at it.
²⁸
When he arrived at Cambridge he decided to read Genetics, the better to combine the two, but not before he’d requested the
Origin of Species
as a school prize.

He was following in Fisher’s footsteps. Soon, accompanied by awe and trepidation, he discovered Fisher himself, white haired in carpet slippers in his room at Saint John’s. The meeting between the two never developed into a relationship, however; Fisher’s mind, it seemed, was by this time somewhere else. Hamilton’s encounter with
The Genetical Theory of Natural Selection,
on the other hand, had been positively transformative. “This is a book,” he later wrote, “I weighed as of equal importance to the entire rest of my undergraduate Cambridge BA course.”
²⁹
It was also a book not taught at Cambridge, where one of his professors representatively acknowledged Fisher’s importance as a statistician but wondered out loud whether he had any qualifications in biology. In zoology, it seemed, the “good of the species” had conquered everything, another professor’s book starting: “Insects do not live for themselves alone. Their lives are devoted to the survival of the species whose representatives they are…,” and so on. Fisher’s emphasis on natural selection always working at the level of the individual was ignored. Even natural selection itself was scarcely respected anymore at Cambridge.
³⁰

And so Bill Hamilton did what he had always done as a boy in the woodlands: strike his own path. To his sister Mary he admitted that Fisher’s mathematical reasoning was “rather beyond me,” but he plugged away nonetheless, spending months in solitude on each chapter. The eugenic bits on civilizations, especially, had snagged him. “I now know why they decline, and how to stop them,” he wrote to Mary. Cultural progress, he had suckled from the bosom of his hero, depended on natural selection.
³¹

A convert to evolution by natural selection working to maximize individual fitness, he’d need to tackle the kind of behavior Darwin himself said would annihilate his theory completely if even one instance of it could be convincingly documented.
³²
He had read Fisher on butterfly distastefulness and Haldane on drowning cousins, and yet, he’d later remember, “one reads and forgets.”
³³
After all, however comprehensive the two giants’ treatments of evolution, they had devoted only a few paragraphs to the problem, and surprisingly not attempted a comprehensive mathematical model. Besides, treating it as a phenomenon related to Military Cross winning, as both had tended to do, seemed to confuse things. Still, clearly, Hamilton thought, the genetics of behavior was a subject relevant to animal and plant as well as man. If the geneticists at Cambridge didn’t see the point, or the social anthropologists what connection it had with genetics, he would go elsewhere to pursue his puzzles. Just twenty-two, a gentle and shy loner with a shock of thick hair, workman’s hands, massive jaw, and the general appearance of a Neanderthal, Bill Hamilton had found his problem: the evolution of altruism.

Already he knew: Feelings for family are not the same as for strangers. As the badgers for whom the hill of his childhood was named made famous, protecting kin was a risky but prevalent affair. Why should this be so? Pondering the question, he put in an application to become a teacher, just as Fisher had done before him. But his genetics degree, the good people at the School of Education at Moray House teachers’ training program in Edinburgh informed him, would only qualify him for junior high. Cuddling the snub, he thought about becoming a carpenter.

Finally he walked into the office of Lionel Penrose, Galton Chair of Genetics at University College London. Haldane was by now working at the Indian Statistical Institute and living in an ivory tower in Orissa. No, Penrose intoned coldly to Bill, he didn’t see the connection between a moral trait like altruism and genetics. Recently he’d changed the name of the
Annals of Eugenics
to the
Annals of Human Genetics
, and would have no talk of genes for human behavior. At best the genetic evolution of altruism was a waste of time; more to the point, it was pernicious. Morphology was one thing, but hadn’t the Third Reich been enough?
³⁴

Whether Penrose really believed this, Hamilton was not certain. The times had seen a strong environmentalist backlash, but to him it all seemed maudlinly political. He had a sneaking suspicion that, as in the old
Punch
cartoon, Penrose was trapped and wishing it all to go away: “Have you heard that Mr Darwin says that we are all descendant from the ape?” one shocked Victorian lady asks the other. “Oh, my dear—that surely cannot be true!…But, if it should be true, let us pray that at least it will not become generally
known
!”
³⁵

To contemplate the biology of character was to think “the socially unthinkable” after
Mein Kampf
and the Final Solution it was positively verboten. At stake, rather than religion in Darwin’s day, was the egalitarian premise of democracy, not to mention the delicate politics of race. Penrose acknowledged a Cambridge genetics degree, and offered Hamilton work on classical fly genetics; for the evolution of altruism he’d need to go elsewhere. Luckily, unlike Penrose, Professor Norman Carrier of the Department of Human Demography at LSE seemed “quite unaware of even a possibility that I might be a sinister new sucker budding from the roots of the recently felled tree of Fascism, a shoot that was once again so daring and absurd as to juxtapose words such as ‘gene’ and ‘behaviour’ into single sentences.” The friendly Carrier didn’t quite grasp the project but was encouraging and helped Bill secure a studentship.
³⁶