22 Feb 2013 19:05:56
As a young man, WD Hamilton (born 1936) was fascinated by heroic death. Where did it come from, this courage to sacrifice all? And as a budding naturalist, he pondered self-sacrifice in the rest of the natural world. Other species do not have to ignore knowledge of mortality to risk everything, but the reproductive puzzle persists. A vervet monkey's alarm call to warn of a predator triggers escape for others, but increases its own chances of becoming lunch. A bee that stings an intruder to the hive dies.
When Hamilton looked to explain these and less dramatic examples of behaviour which, in people, we would call altruistic, the leading idea was that Darwin's blind watchmaker, natural selection, could operate on a group as well as an individual. One creature's loss could still benefit the group as a whole. There was something cosy and communitarian about group selection that appealed to biologists after the second world war. But Hamilton would have none of it. He went down a level, instead. Selection for him operated on the units of inheritance – on the genes that made Darwin's theory complete.
His insight was that the "gene's eye view" could explain altruism. One individual's loss was outweighed by another's gain, discounted by a factor measuring their degree of relatedness – which captures the probability that they have genes in common. Your death is worthwhile, genetically, if eight cousins survive as a result.
The principle, inclusive fitness, seems simple. Tracing it at work in real ecosystems quickly becomes complex. Fortunately, Hamilton, a superb naturalist from his own boyhood in Kent onwards, had an enormous catalogue of species in his mind, along with first-hand knowledge of many of them. And while Darwin himself retreated to Kent not long after his round-the-world voyage on HMS Beagle, Hamilton returned again and again to the Amazon, to delve repeatedly into the most biodiverse patch of the planet. He proudly estimated he had accumulated 1,000 wasp stings while out collecting.
When Hamilton ("Bill" throughout Ullica Segerstrale's absorbing biography) died at the turn of the millennium, after a visit to the Congo to test a theory about Aids, he was widely regarded as the most important evolutionary theorist since Darwin. Segerstrale explains in great detail what he achieved over 40 years of intense application to fitness puzzles. She plots a clear path through the thickets of evolutionary algebra, and the often tangled relations between its leading exponents. Her monumental earlier study of the sociobiology controversy, Defenders of the Truth, stands her in good stead here. She also impresses in balancing her obvious affection for Hamilton with a clear-eyed view of his foibles.
Along with a fertile mind and an eye for patterns unseen by others, Hamilton had a remarkable "feeling for the organism" (as was said of another great scientist, geneticist Barbara McClintock), but not generally for other humans. He tried to overcome this by analysing them, but this only seems to have worked when he modelled their behaviour accurately, and he only did this when that behaviour resembled his own.
Segerstrale's own sociologist's eye highlights this problematic combination. She is less sure-footed as an academic writer seeking a popular touch. Her introduction promises to relate "a classic case of misunderstood genius", but this seems a poor fit for a man whose first big idea was taken up within a decade by some of the most gifted popular writers biology has ever seen – EO Wilson, in Sociobiology, and Richard Dawkins in The Selfish Gene. In the 1990s, his other most influential idea – that the evolution of sex was driven by the advantages of resistance to parasites – was the central pillar of another pop-science bestseller, Matt Ridley's The Red Queen. He died laden with late-career scientific honours.
This was a great relief, as his obsessive streak spilled over from his science to a preoccupation with recognition. He resented the fact that, as he saw it, he had trouble getting published. True, he had trouble getting his first papers in Nature, but then obscure doctoral students usually do. He also nurtured an enduring grievance against the other great English evolutionist of the time, John Maynard-Smith, which began in the 1960s and acquired new layers a decade later when Maynard-Smith reminded readers of the New Scientist that his own mentor, JBS Haldane, had spoken about the basic maths of inclusive fitness after, as he put it, doing some work on the back of an envelope.
Maynard-Smith described Hamilton's contribution as "the decisive step" in the same piece, but Hamilton saw it as belittling his own achievement as well as challenging his priority. A testy public correspondence followed, which Hamilton opened up again privately two years later. Such an English dispute this. Hamilton (Tonbridge School, Cambridge), writes at length about his feelings of hurt and resentment. After more or less accusing the other man of plagiarism and of fabricating his story about Haldane he tops it by charging that Maynard-Smith (Eton, Cambridge) has been "not quite gentlemanly". Maynard-Smith is, naturally, "very distressed" by this.
Segerstrale falters in a few places where more painstaking explanation would help the lay reader stay with the story. Agent-based modelling and genetic algorithms became crucial to developing Hamilton's understanding of the interaction between hosts and multiple parasites. What exactly are they? You'll have to look them up elsewhere. A pity this, and it's not for lack of space; the author is so anxious to convey Hamilton's fixation on self-sacrifice that her usual skill in organisation eludes her, and she repeats the emphasis in several identically worded sentences.
So this may not be the best place to start investigating Hamilton. That would be a book which Segerstrale neglects to mention, Marek Kohn's gracefully written A Reason for Everything (2004), which devotes two chapters to him, but also traces the work of other key English evolutionists. Segerstrale's much fuller account is well worth reading, though. The Hamilton who emerges here is richly complex – a man of penetrating insight and occasional wrong-headedness, devoted to nature but obtuse in many of his dealings with people, a true intellectual but also something of an adventurer. And yes, in his devotion to science and to understanding the twists and turns of natural selection, not to mention enduring those 1,000 stings, in his own way a bit of a hero.
