The Thing with Feathers (27 page)

Superb fairy-wrens have a different social system from that of purple-crowned fairy-wrens. Males pluck flower petals and display them to females for courtship, and females often sneak away before dawn to mate with other males. Rampant promiscuity means that, unlike purple-crowned dads, male superb fairy-wrens are often unrelated to the nestlings in their own nest, and so are the helpers (unless, as sometimes happens, the helpers mate secretly with the female). All this loose living makes you wonder what motivates superb fairy-wrens to breed cooperatively. Maybe helpers are doing it solely to inherit territory rather than to protect family. But are they even really helping?

When a team of researchers led by an Englishman, Andrew Russell, compared the fledging success of young superb fairy-wrens from nests with and without helpers in 2007, there was no measurable difference; although chicks in nests with helpers were fed an average 19 percent more food, they weren’t any healthier. Earlier studies had reached the same conclusion. Russell couldn’t make sense of this result, but he had a theory. If the chicks weren’t benefiting from extra attention, maybe their mothers were.

He carefully measured eggs in a variety of nests and found that eggs were more than 5 percent smaller in nests with helpers than in those tended by just two adults. Smaller eggs also contained a smaller proportion of yolk and nutrients. When females could rely on a bigger family to raise their chicks, it seemed that they put less energy into their eggs. At hatching, those chicks emerged wimpy and underweight. But with additional fairy-wrens bringing them extra food, scrawny chicks
grew faster, and by the time they left the nest, they’d caught up to normal fledglings with two parents.

Then, critically, Russell looked at the long-term survival of the mothers. Adult female fairy-wrens who lived with just one male had a one-in-three chance of dying within one year. But for females with helpers, those odds were reduced to one in five. Russell’s results made the cover of the journal
Science
. In superb fairy-wrens, cooperative nesting doesn’t really help the kids. It’s the moms that soak up all the benefits.

—

IN THE 1980S,
Martin Nowak, a graduate student in mathematics, became so fascinated by Robert Axelrod’s classic prisoner’s dilemma studies that he dedicated his thesis to the subject. Nowak wanted to beat the Tit for Tat strategy. What if, instead of crafting a single unchanging algorithm, he could grow a winning strategy organically through generations of breeding?

Nowak, working with his Ph.D. adviser, Karl Sigmund—who was one of the first to apply mathematical game theory to evolution—modeled a population of creatures, each with different random initial strategies of cooperation. Then he let those creatures interact in prisoner’s dilemma situations over time, mirroring the rounds in Axelrod’s tournaments; each one would always remember previous rounds. But Nowak added some new rules. He introduced strategic mutation, as you’d expect in any population of animals. He also forced occasional errors so that each strategy would sometimes cooperate when it meant to defect, and vice versa. Finally, he modeled selection: Successful strategies reproduced, while unsuccessful ones died out.

At first, with no history of interactions, defectors dominated. But after just a few generations, the Tit for Tat strategy
suddenly outcompeted the betrayers. Tit-for-Tatters ruled for another dozen generations, but then, in an unexpected stroke, they gradually began to be replaced by a mutated version that Nowak called “Tit for Tat with forgiveness”—a strategy that copied its opponent’s actions but occasionally cooperated even when its opponent defected. Forgiveness tended to score more than simple retaliation, so the population swung toward nicer strategies until virtually all individuals were cooperating all the time, in stark contrast to the beginning of the model. At that point, things became so unstable that when a few mutations introduced individuals who preferred betrayal, the cooperators were overtaken and the cycle reset.

Nowak’s effects became even more striking when he added the element of reputation. Actions could now take into account not only one’s own past but also the pasts of others. The population trended toward cooperation because it paid to be nice to the ones most likely to return the favor. When it reached a certain critical point, a few uncooperative strategies still took over and the cycle began again, but this time with a twist. Sometimes, clusters of truly cooperative individuals would emerge that, by interacting mostly with one another, could not be brought down with any amount of outside betrayal.

Nowak’s model demonstrated that different strategies may succeed, depending on circumstances. Nobody can be nice all the time. But it also showed a fascinating rise of cooperation from the dry dust of random math, and suggested that cooperative behavior is not only beneficial but perhaps part of evolution.

Complex societies just can’t function without cooperation. If nobody ever cooperated, we’d all still be single-celled organisms swimming in the soup—and, it should be noted, even unicellular slime molds can act socially. At some point, two cells
had to get together, each sacrificing a bit of its own freedom to form something more ordered.

Everywhere he looked, Nowak saw examples of cooperation. He delved into the evolution of language, which he perceived as a bunch of people cooperating. He turned his attention to the mathematics of cancer, which he viewed as a bunch of cells not cooperating. The more he thought about it, the more he became convinced that cooperation was no mere feel-good behavior; it must be vital to life itself. His book
SuperCooperators
argues that cooperation should be considered a third tenet of evolution, right up there with mutation and natural selection. And he doesn’t leave it there. He believes that we’re all playing one large, strategic game against our future descendants, and that we’d better start cooperating with them or they won’t have much of a world to live in. No model can give us the definitive answer for the end of that game.

—

WHEN THE BLAZING AFTERNOON
melted into a calm evening at Mornington, I set out down a graded dirt track with a lawn chair, a field notebook, and a pair of binoculars. The temperature pushed a hundred degrees even near sunset, and heat wafted off the ground in invisible waves while I meandered past wallabies and fat-bellied boab trees. I marveled at Australia’s red dust, which eventually clogged up every crevice of my shoes. My favorite pair of purple-crowned fairy-wrens lived about a half-mile from the station off that dirt track.

As soon as I reached their nest, I set up my chair on a grassy bank with a good view at a distance that wouldn’t interfere with the birds’ habits. They were used to me by now, but I respected their space. This evening, I hoped to further, by one tiny notch, our knowledge of cooperation in fairy-wrens.

Nest watches help researchers measure exactly how much effort each bird puts into its nestlings. This particular group contained four birds, all attending the same nest with several five-day-old babies inside. There was an adult male—obvious by his purple crown—along with an adult female and two younger helpers. The female and helpers were harder to tell apart, so I had to rely on unique color bands on their legs, which were sometimes difficult to see when the fairy-wrens darted back and forth to the nest entrance.

Watching the nest was far more entertaining than TV. In less than an hour, my tally sheet filled with visits from all four birds, each of which delivered insects at short intervals. The two adults made more visits than the two younger members of the group, but none was slacking. I kept wondering why the younger helpers chose to attend a nest that wasn’t their responsibility.

The more I watched, the more I began to visualize the entire group as a family instead of as a collection of individuals. I couldn’t make myself think of them as selfish, calculating birds, each one trying to game the others with a different strategy. The thing is, those birds didn’t just raise their babies together, they did
everything
as one unit. Whether eating, sleeping, or prowling the edges of their territory, all four members were rarely separated by more than a few yards. When an intruder showed up, they joined in a vocal defense. Sometimes, two of them would sidle up to each other on a branch—usually the dominant male and female, but not always—and tenderly preen each other’s feathers for a few minutes. The male and female also often sang duets with each other, a behavior about as rare as cooperative breeding among birds.

There’s something to be said about being part of a group, I thought, recalling that my own nearest neighbor was nearly 100 miles away. Though the benefits may be hard to measure,
group living must give a certain level of satisfaction to each member, a feeling of belonging, of purpose. In return, each bird must also sacrifice a bit of freedom, just as a couple of single-celled organisms once did to form something more complex. Helping out in chores such as nest duty is part of the deal. You put in what you get out.

—

A GLASS OF ALTRUISM
may be half full or half empty. Scientists and philosophers tend to pick sides, and, though neither is wrong, the camp you choose depends on your worldview.

At least altruism is easy to define. But does the pure thing actually exist? To science, no good deed can be proven to be completely altruistic because there is always the possibility of hidden benefits. You might as well try to confirm or deny the existence of magic. It’s really a matter of personal philosophy.

Optimists like to bring up charities as a shining example of human altruism. Anyone who donates to charity, they argue, can’t possibly expect to be repaid—such organizations, by definition, benefit only those who have nothing to give in return. Because philanthropists make gifts with no strings attached, they seem to fit the definition.

But then the “half empty” folks step in. First off, they say, most people who make charitable gifts do so at negligible cost to themselves. For instance, Bill Gates gives away 95 percent of his wealth—a laudable effort—which leaves him with, oh, a couple billion left in the bank. He could buy an extra fleet of Ferraris instead, but that would make no difference to the man’s ultimate survival or status. He’s already made his fortune, so he can afford to give some away.

And those who donate to charity may receive a benefit more potent than currency: Their friends will hear about it.
Reputation is a powerful force. As Martin Nowak’s model showed, it can even affect decisions as basic as whether or not to cooperate with a stranger. Your reputation spreads beyond your circle of friends and lingers after your death. Most people want to leave a legacy.

Even anonymous gifts may not be truly altruistic. Consider the group of unknown donors that recently decided to cover college tuition for every kid, present and future, who graduates from high school in Kalamazoo, Michigan. Surely, that’s as altruistic as it gets—those kids don’t even know who to thank for their free ride. But aside from the obvious economic impacts of such a promise on the city, which will inevitably trickle down to its distinguished citizens, those donors can count on a more subtle and immediate benefit: personal satisfaction.

Don’t underestimate that warm, fuzzy feeling. In a recent study of giving and its effects on the human brain, subjects were analyzed while they made anonymous decisions about where to direct funds for charity. Scans showed that the mesolimbic pathway—the part of our brain associated with intense pleasures, such as food and drugs—lit up when people decided to give away their money, suggesting that generosity fulfills us on a primal level. In another study, participants were given five dollars to spend by the end of the day either on themselves or on gifts, and those who bought presents for others reported feeling significantly happier than those who spent the cash on themselves. It turns out that money
can
buy happiness, but only if you give it away.

Because satisfaction is a benefit, it technically violates the definition of altruism. But the argument begins to seem curiously circular: Altruism doesn’t exist because it makes you happy.

Of course it makes you happy. I watched the story unfold
between those purple-crowned fairy-wrens in the rough Australian outback. They probably got a little spike of pleasure with every positive interaction, whether by bringing extra food to a nest or snuggling up together on a branch for a session of mutual preening. Helpers may further their own genes and inherit better territories, but those very particular benefits are part of a larger system of day-to-day behavior. Fairy-wrens are social creatures, just like us. Their brains probably light up with pleasure every time they do good, the same as ours do.

People who have performed extremely heroic acts, such as diving into a burning building to save a child, invariably report feeling a sense of duty rather than the urge to flaunt their bravery. Any decision to risk your own life to save another’s is entirely voluntary and selfless, yet the people who do it don’t even think about it—those decisions are based on a larger code. If you think altruism doesn’t exist, then you believe that heroes don’t, either—that the selfish reward they get from saving a life is calculably greater than the life itself.

With its insistence on measurable quantities, science will probably never get to the bottom of the altruism debate—especially in animals. There’s no particular reason why humans should be different in this regard; we have the same capacity (if not more) to bond with one another as fairy-wrens and many other social creatures. Reward and fulfillment exist no matter who you are, but they are tough to measure.

In the nearly 1,000 hours I spent watching fairy-wrens in the outback, I became convinced that if cooperation in fairy-wrens is just a game, then at least it’s a game they play because it gives the birds some immediate sense of fulfillment. Their altruistic behavior seems to reflect an overall code of living as much as an evolutionary imperative; fairy-wrens behave generously because that’s the kind of bird they are, and everything works
out. While you might conclude, from mathematical theory, that their helpful behavior is coldly calculating, this judgment confers our own values on the birds as much as the suggestion that they behave strictly out of love for one another. And the debate misses an ultimate point. Sure, we can never know whether or not real altruism exists in this universe, but wouldn’t it be wise for us—considering the bleak alternative—to take a cue from fairy-wrens, and act as if it did?