Fit to What?

00:00A letter from Wallace

On the second of July, 1866, Alfred Russel Wallace sat down to write a letter to Charles Darwin about a word. Wallace was the other man who had come up with natural selection, independently, in the jungles of the Malay Archipelago, and he was its most loyal defender. And he had a complaint. He had been struck, he wrote, again and again, by the "utter inability" of large numbers of intelligent people to see what natural selection actually meant. They read the phrase and pictured someone doing the selecting. A breeder, a chooser, nature with a clipboard. So Wallace proposed a fix. There was a phrase a philosopher named Herbert Spencer had been using, and it said the same thing with no chooser in it at all. [pause] "Survival of the fittest." [pause] Darwin wrote back three days later and agreed. He worked the phrase into his next book, and into the fifth edition of *On the Origin of Species*. And that is how a phrase Darwin didn't write, chosen to make his idea harder to misunderstand, became the most misunderstood thing he's known for. [pause] [casually] Hi, it's Qing. Today is about one word in that phrase, "fittest," what it meant to the people who used it, and an argument it started between a famous English biologist and a Russian prince who had spent five years in Siberia looking for a fight among animals and mostly couldn't find one.

01:43The struggle, in a large sense

Start with the book itself, because Darwin was more careful with his words than his reputation suggests. In the third chapter of the *Origin*, the one called "Struggle for Existence," he stops to explain what he means by "struggle." He uses it, he says, "in a large and metaphorical sense, including dependence of one being on another." Then he gives examples. Two dogs in a time of famine, he says, may truly be said to struggle with each other over which one will eat. Fine. That's the picture everybody has. But then: "a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture." [pause] Read that again and notice who the plant is fighting. Nobody. There's no opponent. The struggle is between a living thing and its conditions, and the word Darwin reaches for to describe it more properly is "dependent." [pause] He gives another one. A mistletoe plant depends on the apple tree it grows on, and on the birds that carry its seeds. You could say it struggles with other fruit-bearing plants to get the birds to eat its berries instead of theirs. But that kind of struggle looks a lot more like being attractive than like winning a fight. [pause] So even before "survival of the fittest" entered the book, the idea underneath it was wider than a contest of strength. It was about how well a creature's life matched the place it had to live.

03:24What "fit" meant

That's also what "fit" meant. In nineteenth-century English, the main sense of fit wasn't "in good shape," the way we use it now for someone who goes to the gym. It meant suitable, well matched. A key fits a lock. A coat fits a person. Spencer's own sentence, in his *Principles of Biology* in 1864, put it in those terms: "This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection.'" The fittest is the one that fits best. Fits what? Whatever is there: the food, the weather, the predators, everyone else. [pause] Once you hear it that way, something follows that the gym version hides. Fit is not a property of an animal. It's a relationship between an animal and a place, at a particular time. Change the place, and the fittest changes. [pause] There's a famous example of exactly that, watched in real time. On a tiny volcanic island in the Galápagos called Daphne Major, the biologists Peter and Rosemary Grant spent decades catching, measuring and banding nearly every finch. In 1977 a drought hit, almost no rain at all, and the small soft seeds the finches liked ran out. What was left were big, hard seeds that took a strong, deep beak to crack. Most of the medium ground finches died. The ones that lived were, on average, the bigger birds with deeper beaks, and their chicks inherited those beaks. Evolution, measured with calipers, inside a few years. [pause] And then the island changed again. In the early eighties came a huge El Niño, very wet years, and the plants with small seeds came back in force. When the next dry stretch came, the advantage swung the other way, toward smaller birds. Same species, same island. The fittest bird of 1977 was not the fittest bird a few years later. Nothing about the birds had gotten better or worse. The lock had changed.

05:45A gladiator's show

The other reading, fit as strong, as ruthless, as the one left standing, had powerful friends. One of them was Thomas Henry Huxley, the biologist who was so fierce in defending Darwin that people called him "Darwin's bulldog." In February 1888 Huxley published an essay called "The Struggle for Existence" in a magazine called *The Nineteenth Century*. It's a gloomy, brilliant piece of writing, and it contains one of the most quoted images in the whole debate. "From the point of view of the moralist," Huxley wrote, "the animal world is on about the same level as a gladiator's show." The animals are well fed, set to fight, and the strongest, the swiftest and the cunningest live to fight another day. [pause] [slowly, thoughtfully] To be fair to Huxley, he wasn't saying humans should live that way. His point was close to the opposite: that nature is brutal, and human ethics has to be built against it, not copied from it. But the picture of nature itself, a ring full of fighters, he took as simply true. And a lot of readers took it further than he did, toward the idea that competition among people was natural, and therefore fine, and maybe even good. That's the bundle that later got called "social Darwinism," though Darwin's name is the least deserved part of it. [pause] One reader in London was not convinced at all, because he had spent a big part of his youth looking at actual animals in some of the harshest country on earth.

07:31Five years in Siberia

His name was Peter Kropotkin. He was born a prince in Russia, served as an officer in Siberia in the 1860s, and travelled thousands of miles through eastern Siberia and northern Manchuria as a geographer. By 1888 he was a well-known anarchist living in exile in England. Huxley's essay made him angry enough to start writing a reply, a series of articles in the same magazine through the 1890s, and in 1902 he collected them into a book called *Mutual Aid*. [pause] In the introduction he describes what had struck him in Siberia. Two things, he says. The first was how severe the struggle against nature was: the cold, the storms, the sudden snows that could wipe out whole populations of animals. The second was that even in the few places where animal life was abundant, he "failed to find," even though he was looking for it, the bitter fight among animals of the same species that he'd been taught to expect. What he saw instead, again and again, was animals helping each other get through. Birds flocking, deer gathering in herds to migrate, animals that survived by banding together. [pause] He wasn't the first to say this. He credits a Russian zoologist, Karl Kessler, who gave a lecture in January 1880 called "On the Law of Mutual Aid." Kessler's point was that, in the long run, mutual aid mattered more to the progress of a species than mutual struggle. Kessler died shortly after. Kropotkin spent the next twenty years building that one lecture into a book. [pause] Kropotkin overstated his case in places, and he was an anarchist with a political point to make, which is not a reason to dismiss him but is a reason to read carefully. Later biology found harder mechanisms for cooperation than he could give: helping your relatives, who share your genes, or helping others who'll help you back. But the core of his argument, that cooperation can be one of the ways a creature fits its world, has held up well.

09:56What Darwin had already written

Here's the part that would have helped Kropotkin, and he did use it. Darwin had already said much of this himself. In *The Descent of Man*, in 1871, he writes about animals that are social, that warn each other, groom each other, defend each other. And then he applies the same logic to early human groups. In a contest between tribes, he says, the communities "which included the greatest number of the most sympathetic members would flourish best, and rear the greatest number of offspring." [pause] Take that sentence slowly. It's natural selection, in plain terms. It's about who survives and leaves children. And the trait that's winning is sympathy. Not strength, not cunning. The fit group, in Darwin's own argument, is the one whose members care about each other. [pause] So by the late nineteenth century you had the same theory being read two ways. In one, struggle meant a fight, and fit meant the fighter who won. In the other, struggle meant the whole effort of staying alive in a hard place, and fit meant whatever worked there, which could be claws, or a deeper beak, or a flock. Darwin's own pages lean toward the second reading more often than people expect. The phrase "survival of the fittest," cut loose from those pages, leaned toward the first.

11:29The entangled bank

[casually] Here's what I'd take out of all this. When someone says "survival of the fittest" to explain why the toughest, or the richest, or the most ruthless come out on top, the useful question is a short one: fit to what? Fit to which conditions, at what moment? Because fitness isn't a ranking from best to worst. It's a match, and it's local. A beak that saves you in a drought is a burden in a wet year. A habit that pays in one setting, a company, a family, a field, can be the wrong shape in the next one. And cooperation isn't the soft exception to the rule. Sometimes it's what fitting looks like. [pause] Darwin closes the *Origin* with a picture that's worth more than the phrase. He asks you to look at a tangled riverbank, covered with plants of many kinds, birds singing in the bushes, insects flitting about, worms crawling through the damp earth, and to reflect that all these elaborately constructed forms, so different from each other, and "dependent on each other in so complex a manner," have all been produced by the same laws. [pause] Dependent on each other. That's the image he chose to end on. And the very last word of the first edition, before he'd ever heard of Spencer's phrase, is "evolved." It's the only time that word appears in the whole book. [pause] See you Thursday.