Why We Help [Preview]

Far from being a nagging exception to the rule of evolution, cooperation has been one of its primary architects

In Brief


  • People tend to think of evolution as a strictly dog-eat-dog struggle for survival. In fact, cooperation has been a driving force in evolution.
  • There are five mechanisms by which cooperation may arise in organisms ranging from bacteria to human beings.
  • Humans are especially helpful because of the mechanism of indirect reciprocity, which is based on reputation and leads us to help those who help others.


In april 2011, as reactors at japan's fukushima daiichi nuclear power plant were melting down following a lethal earthquake and tsunami, a maintenance worker in his 20s was among those who volunteered to reenter the plant to try to help bring things back under control. He knew the air was poisoned and expected the choice would keep him from ever marrying or having children for fear of burdening them with health consequences. Yet he still walked back through Fukushima's gates into the plant's radiation-infused air and got to work—for no more compensation than his usual modest wages. “There are only some of us who can do this job,” the worker, who wished to remain anonymous, told the Independent later, in July. “I'm single and young, and I feel it's my duty to help settle this problem.

Although they may not always play out on such an epic scale, examples of selfless behavior abound in nature. Cells within an organism coordinate to keep their division in check and avoid causing cancer, worker ants in many species sacrifice their own fecundity to serve their queen and colony, female lions within a pride will suckle one another's young. And humans help other humans to do everything from obtaining food to finding mates to defending territory. Even if the helpers may not necessarily be putting their lives on the line, they are risking lowering their own reproductive success for the benefit of another individual.

For decades biologists have fretted over cooperation, scrambling to make sense of it in light of the dominant view of evolution as “red in tooth and claw,” as Alfred, Lord Tennyson so vividly described it. Charles Darwin, in making his case for evolution by natural selection—wherein individuals with desirable traits reproduce more often than their peers and thus contribute more to the next generation—called this competition the “struggle for life most severe.” Taken to its logical extreme, the argument quickly leads to the conclusion that one should never ever help a rival and that an individual might in fact do well to lie and cheat to get ahead. Winning the game of life—by hook or by crook—is all that matters.

Why, then, is selfless behavior such a pervasive phenomenon? Over the past two decades I have been using the tools of game theory to study this apparent paradox. My work indicates that instead of opposing competition, cooperation has operated alongside it from the get-go to shape the evolution of life on earth, from the first cells to Homo sapiens. Life is therefore not just a struggle for survival—it is also, one might say, a snuggle for survival. And in no case has the evolutionary influence of cooperation been more profoundly felt than in humans. My findings hint at why this should be the case and underscore that just as helping one another was the key to our success in the past, so, too, is it poised to be vital to our future.

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