The Price of Altruism Page 9
Partly this was related to dialectics. Fisher worshiped the purifying hand of natural selection, but Haldane thought it had to be “negated” somehow by the chanciness of genetic mutation.38 This didn’t mean that natural selection wasn’t a force to be reckoned with: Thirty years before the Oxford geneticist E. B. Ford sent his student Bernard Kettlewell to the forests outside Birmingham to prove it, JBS predicted that the dark peppered moth, the melanic Biston betularia, could hold up to a 50 percent selective advantage over its white counterpart. In the span of only a few generations, its ratio in the population compared with the white morph had jumped from 2 percent to over 90, the Industrial Revolution having provided blackened birch trunks to hide from preying birds, and left the rest to natural selection.39
But if natural selection was driving populations to higher fitness, it was also being frustrated by mutation. Fisher argued that fitness depended on variation, but this led to a paradox: After all, the more natural selection weeded, the less variation was left. This meant that the mutation rate had to be higher than he allowed for. But since most mutations were harmful, if their rate was too high the fitness of the population would drop. On the other hand, if natural selection scrutinized too harshly, the population could be wiped out entirely. There had to be a dialectic, to JBS this was clear. From the mouth of Marx via Hegel,40 whatever the fundamental theorem promised, there was a cost to natural selection.41
Evolution had accomplished amazing feats but was no panacea. Where Fisher had turned to a divine Nature and the upper classes, Haldane chose radical politics. He’d been back from the Spanish civil war for some years now, and had recently been elected to the executive board of the Communist Party of Great Britain. Sure, he had heard of the rise in the Soviet Union of the Ukrainian farmer Trofim Lysenko, who marshaled Marxist doctrine to lambast “Western, bourgeois, exploitative” genetics, calling its practitioners “fly lovers and people haters.” He had heard that the “barefoot professor” was promising a “genuine,” “proletarian” agricultural revolution based on false Lamarckian claims, and whispering into Stalin’s ear that “determinist” and “racist” genetics needed to be shut down. He had heard the rumors of colleagues losing their jobs, of the disappearance of his gracious host Vavilov, even of executions and purges. But he waved them all aside. There was no hard evidence. Besides, even if Lysenko’s claims were “seriously exaggerated” there might be a grain of truth to them.42
Haldane was a hereditarian. Back in 1932 he had remarked: “The test of the Union of Soviet Socialist Republics to science, will, I think, come when the accumulation of the results of human genetics, demonstrating what I believe to be the fact of human inequality, becomes important.” He enjoyed quoting Engels’s assertion that “the real content of the proletarian demand for equality is the demand for the abolition of classes” any demand that goes beyond that, he said, “of necessity passes into absurdity.” Though not a rabid eugenicist like Fisher, he judged the logic behind its tenets sound. He was convinced that the mean IQ was falling due to the abstinence of the educated classes. Genetically speaking, capitalism was frustrating the survival of the fittest. By abolishing classes and getting rid of the differential birth rate, socialism would be the perfect corrective.43
This was hardly the reactionary Fisher’s plan, but it was not exactly Lysenko’s either. Pointing his finger at the Nazi perversion of genetics, the “madman” from the Ukraine had convinced Stalin that Mendelism was a noxious sham. It was by changing the environment, not manipulating imagined genes, that man’s destiny would be forged and provided. A French colleague said of Haldane: “Ce n’est pas un homme, c’est une force de la nature!” By all accounts he was a Goliath, a bastion of reason and logic. And yet somehow it didn’t seem to bother him—one of the few modern prophets of evolution—to be apologizing for a man who denied the existence of the gene and called survival of the fittest a bourgeois plot. What mattered was the cause. As long as capitalism had yet to show that it could keep people from want and communism that it could not, Haldane was going to side with the Party.44
Sewall Wright was no kind of Marxist. Nor, in truth, was God usually on his mind. A Harvard trained theoretical population geneticist, he looked a bit like a very handsome mouse. And as colorful as Haldane and Fisher were, Wright was the son of a small college professor from the Midwest whose “idea of a fun night out was a discussion with his university chums at the local faculty club.”45
Still, just like his English counterparts, he’d applied equations to evolution, and even though he was sedate and mousy, the fundamental theorem of natural selection just blew him away.46 Emboldened by its generality, he offered a theory of evolution of his own, grander than Haldane’s engineerlike approach, more visual than Fisher’s obscure but soaring mathematics.47
Life, he explained, was like a landscape of valleys and mountains. Organisms could be imagined in the process of climbing in an upward direction, improving their fitness as they scaled a crest. As the fundamental theorem showed, once an ascent had begun there was no turning back, for natural selection could push in only one direction. This was well and fine. But what if the summit was in fact a foothill, not all that towering: Would organisms find themselves stranded with nowhere else to climb?
Wright’s answer was that in addition to natural selection another force sometimes operated, called “random drift.” Imagine a crowd of a million angry demonstrators walking down Main Street in the direction of Town Hall and one falling accidentally into a pothole. However tragic to the particular individual, the torrent, and the demonstration, will not have been affected. But if only three friends are walking down an alleyway toward a demonstration and one falls randomly into a pothole, it’s almost certain they’ll never make it to the rally; their direction and cause will have changed dramatically. As with demonstrators, so with genes in a population: Chance events will influence small groups much more than large ones. And just as the pothole may have swallowed the friend least interested in the demonstration, genetic drift will be divorced from the “goals” of evolution. Unlike its deliberate older brother, drift would not always push organisms to higher genetic peaks: If natural selection was the taskmaster of fitness, drift was the shifting sands underfoot, changing the course of weak and strong alike.
Still, there was a bright side. If populations were not large and homogeneous, if they didn’t all walk together through Main Street but rather advanced in parallel alleys in small, partially isolated groups, drift could do what natural selection could never accomplish: alter the genetic structure enough to allow a dramatic change in direction. In Wright’s model this was tantamount to blowing a group from a peak into a valley. Working against the fundamental theorem, in the short run it meant a decrease in fitness. But just as a grieving letter to the mayor from one of the two remaining friends might do more for the cause, in the end, than the mass rally, it could ultimately provide a surprising opportunity. For a blow off a foothill might lead to the foot of a new and higher mountain. What looked like a dive would actually mean liberation—the start of a glorious, transcendent new ascent.48
He called it the “shifting-balance” theory, since the population shifted between the poles of directed selection and random drift, respectively. Wright thought of it as an enrichment of the fundamental theorem, chance blowing new tunes into the sometimes limited winds of progress. But the “adaptive landscape” left Fisher cold. Mutations were both necessary and random, but it was the guiding hand of selection that ultimately shaped life. Without it there could be no purpose or end. Wright’s “landscape” was “picturesque” but biologically nonsensical.49 Small isolated groups where random events could leave their mark were either on the way to extinction or becoming new species. The sweeping majority of creatures in a population were continually connected genetically, since each had a fair chance of mating with the other. They were all marching steadily together down Main Street. Drift might shift a handful of genes in a vast, never-ending sea; from
the point of view of the population it was negligible.
Nature was uniform, not a landscape of troughs and peaks. And the great ocean of life was constantly rising.
Fisher, Haldane, and Wright would become known as the architects of the evolutionary synthesis, each in his own way wedding Darwin to Mendel.50 However different their models, all three celebrated the power of natural selection to bring about evolution. For that reason, too, just like Darwin before them, they were puzzled by the conundrum of the ants: How could traits that reduced fitness be selected, going against the interest of those who bear them? Traits, that is, like altruism.
Fisher’s reply came via butterflies and caterpillars. Naturalists were familiar with butterflies (and other insects) that are terribly distasteful to the birds that try to eat them. This would be a wonderful defense if only the birds knew it before taking a bite. Since such understanding usually came too late for the butterfly, Fisher wondered how “distastefulness” could have evolved.51
When his entomologist friend E. B. Poulton told him that most butterflies, like the monarch, have bodies tough enough to survive a bird’s first bite, it looked as if the problem went away: If the monarch could survive the initial munch, its distastefulness would mercifully save it. But what about monarch caterpillars? They had “nauseous flavors,” too, and yet were as soft as silk. If a bird took a chomp out of one of them, no matter how distasteful, the defense would have been too little too late.
The answer resided in the family. Before caterpillars grow wings they are less mobile and tend to stick together, usually in groups of related kin. If a hungry bird looking for a meal chanced on such a clump it might take a bite out of one but spare the rest, disgusted. The unlucky caterpillar would have sacrificed itself for its brothers and sisters, losing its life in a final act of gallant altruism.
It made sense, Fisher thought, because kin are genetically related: Natural selection could produce kamikaze distastefulness in individuals to ensure that more of their shared genes lived on in the bodies of the brothers and sisters who were spared. The less related the caterpillars in the clump, the more the selective effect “will be diluted,” and the less chances of altruism to evolve.52
The importance of relatedness had been clear to Fisher as far back as 1918, when he presented in his famous paper a table calculating genetic distances between kin. But it was Sewall Wright, four years later, who provided the variable that was adopted to measure kinship.53 He called it the “coefficient of relationship,” or r, and proved that for an individual and any of its direct descendants it was equal to 0.5n where n is the number of generations that separate the two. Between mother and son it equals 0.5 (0.51), between grandparent and grandchild 0.25 (0.52) and so on. r was the measurer of genetic relatedness—the probability that two individuals shared a common gene. More generally, then, Wright could now calculate the r of any two related individuals, not just those who were direct ancestors and descendants.
Figuring out the r of two maternal cousins, for example, worked like this: Calculate the probability that both possess a gene, A, that they inherited from their maternal grandmother (for each cousin separately this equals 0.52, meaning that together the probability is 0.52 x 0.52 = 0.0625). Then employ the same procedure to calculate the probability that both cousins got gene A via their maternal grandfather, which likewise equals 0.0625. Finally, add the two sums to get the probability that the cousins share gene A from either of their maternal grandparents (0.0625 + 0.0625 = 0.125). Two maternal cousins, that is, have an r of 1/8, or a one in eight chance of sharing a gene inherited through their maternal grandparents.54
Even though it would one day prove a key to solving the conundrum, Wright never applied r to the problem of altruism. Instead, more than twenty years later, in 1945, he offered a theoretical model of the evolution of altruism that paid little heed to relatedness. Once again random drift was at the crux.55
By definition altruistic traits reduce fitness, and are therefore bad for the individual. But imagine a mixed population of altruists and selfish folk marching together down Main Street: If, just by chance, a bunch of altruists exclusively got sidetracked into an alley, they would make it to Town Hall quicker than the rest of the group. The reason would be that they’d all be helping one another rather than some of them competing to get there first, as would be the case on Main Street. The remaining altruists on Main Street, on the other hand, would not fare as well, since while they were taking time to help others walk down to the destination, the selfish folk would be speeding down to Town Hall.
Within a mixed group, that is, an altruist would suffer from intergroup competition at the hands of those out for themselves, but between, or intragroup, competition would favor groups with a greater proportion of altruists. In terms of the adaptive landscape, if altruists were blown off different peaks and somehow found themselves all grouped at the foot of the same mountain, they might start an ascent that would place them on the highest peak of all.
Wright’s model depended on “group selection,” on natural selection sometimes weeding out or favoring whole groups rather than individuals. But while it made sense that groups with more altruists would do better than groups with fewer, the math proved a problem: It would work only if the alleyways were almost completely isolated from one another, which in turn made it very difficult for altruists to stumble into them by chance. Naturalists, as opposed to pen-and-paper men like Wright, knew that such stringent conditions would be tough to find in nature.56
Where Fisher turned to caterpillars, and Wright to isolated groups and drift, Haldane looked to the ruminants for his stab at the natural origins of kindness. “Of two female deer,” he wrote in an essay from 1928, “the one which habitually abandons its young on the approach of a beast of prey is likely to outlive the one which defends them; but as the latter will leave more offspring, her type survives, even if she loses her life.”57 The logic of selection was often cruel but always plain.
Still, what did distasteful caterpillars and protective mother deer have to do with humans? Could the very same animal logic pertain to man?
However much he believed in worker solidarity, Haldane was a lover of mankind who trusted no one. He agreed with Fisher that evolutionarily speaking, altruism was a family affair. “I doubt if man contains many genes making for altruism of a general kind,” he wrote, “though we probably do possess an innate predisposition to family life…. For insofar as it makes for the survival of one’s descendants and near relations, altruistic behavior is a kind of Darwinian fitness, and may be expected to spread as a result of natural selection.”58
Remembering his brother, Fisher agreed. After all, the hero might lose his life in battle, but his heroism would survive. The reason was that it was coded in his genes. Since relatives share genes, and since, “by repute and prestige,” the act of valor confers an advantage on the family, the grieving but proud surviving kin will pass “hero genes” along in greater numbers.59 Alwyn’s sacrifice in Flanders had not been in vain: Fisher’s eight children with Nicolette would make sure of that.
Whether he had carried his aristocratic sensibility into the realm of determinist genetics or the other way around, a man was the sum of his genes. It was a sentiment Haldane could warm to, however far he lay from Fisher on the political spectrum. “Let us suppose,” JBS wrote, fleshing out the argument,
that we carry a rare gene that affects your behavior so that you jump into a flooded river and save a child, but you have one chance in ten of being drowned, while I do not possess the gene, and stand on the bank and watch the child drown. If the child’s your own child or your brother or sister, there is an even chance that the child will also have this gene, so five genes will be saved in children for one lost in an adult. If you save a grandchild or a nephew, the advantage is only two and a half to one. If you only save a first cousin, the effect is very slight. If you try to save your first cousin once removed the population is more likely to lose this valuable gene than to
gain it…. It is clear that the genes making for conduct of this kind would only have a chance of spreading in rather small populations when most of the children were fairly near relatives of the man who risked his life.60
He then added, with his usual mix of bravado and wit: “But on the two occasions when I have pulled possibly drowning people out of the water (at an infinitesimal risk to myself) I had no time to make such calculations.”61
Haldane’s wit aside, a generalized mathematical model was still lacking. To truly assert itself—Fisher, Haldane, and Wright’s prodigious talents notwithstanding—the evolution of kindness would have to wait for a new champion.62 Still, relatedness had met altruism, for the benefit of the drowning, scaling the political gamut where ideology had failed. Huxley aside, not to mention organized religion, altruism was an offspring of evolution. It was a breathtaking notion. Legend had it that Haldane had first described its logic stooped drunk over a beer in London: “I’ll jump into a river for two brothers and eight cousins,” he was said to have blurted out just before collapsing on the bar.63
Fisher was knighted in 1952, and sought a quiet retirement in Australia. After the war friends and colleagues at Cambridge wondered about his friendship with Mussolini’s former demographic adviser, Corrado Gini, and with Otmar von Verschuer, a medical geneticist and “one of the most dangerous Nazi activists of the Third Reich.”64 He was a strange bird, Fisher—aloof, exacting, imperious, oblivious; too reactionary, people said, to be either a Nazi or a fascist. Instead, he went to his grave an apostle of Nature. It was she who knew what was best for mankind.