Survival of the kindest: The evolution of sympathy

(TONY AUTH / The Philadelphia Inquirer (

Darwinism is more often associated with the liberal left than the conservative right, but it's moved a long way across the political spectrum from Darwin's day, when it was embraced by advocates of free-market economics, colonialism, and similar ideas today associated with the right.

Apparently, Darwinism is still sometimes invoked in arguments for economic conservatism. It's reflected in a recent e-mail I received from a reader: "Maybe you should write about the current reversing of evolution by humans, using technology. . . . Fitness, in humans, means the intelligence and ability to deliver a healthy child. . . . Today, especially in the USA, the least fit make the most offspring while the more fit have the least children. The most fit pay to insure the survival and future breeding of the least fit."

Let's leave aside the part connecting fitness and intelligence for another column, since the term fitness has a very specific meaning in evolution apart from what people try to achieve in the gym. Instead, I'll focus on the idea that helping people interferes with evolution.

I find this letter so intriguing because it reflects the reaction some people had to Darwin's publication of On The Origin of Species in 1859.

According to University of Massachusetts historian Diane Paul, people of Darwin's time realized that evolution was an ongoing process and that our policies and medical advances would influence its direction.

Some preached that charity and social services impeded evolution - a position that came to be called social Darwinism.

Many Christians of the time opposed that attitude, believing mankind should help the poor and the sick.

Paul said Darwin's writing reflected mixed reactions to the ideas that would later be called social Darwinism. He did, however, hit on an important argument against it in his second book, The Descent of Man: Sympathetic instincts that lead us to aid the helpless are themselves products of natural selection.

That idea has stood the test of time.

"Evolution made us all the things we are by nature - it made us cooperative and selfish," said David Sloan Wilson, an evolutionary biologist at Binghamton University. Evolution, he said, left us with the good, the bad, the beautiful, and the ugly.

By educating children, treating sick people, and doing medical research, we're playing out the generous side of our evolutionary destiny.

There's cooperative behavior everywhere in nature, said Stuart West, an evolutionary biologist at Oxford University. Worker bees, ants, wasps, and other social insects forgo their own reproduction to help the queen. The cells of slime molds cooperate, as do bacteria.

What Darwin couldn't explain was how natural selection led to sympathy. Today, it's still the subject of active research and some controversy.

On the surface, selfish creatures would seem to have a survival advantage over selfless ones. That's what makes it a rich area for research, says Rutgers University professor Robert Trivers. As a scientist, he said, "you're automatically attracted to contradictions - those are the most fruitful to solve."

Individual animals may be torn by conflicting instincts, he said. "One part of a ground squirrel says 'give a warning call,' and another part says 'shut the hell up and get down to the nearest hole.' "

Trivers said half the mystery was cleared up by the late biologist William Hamilton, who realized that natural selection would lead to altruism, even self-sacrifice, among closely related individuals. A mother who risks her life to protect her young may pass on more of her own genes than a mother who does not. Worker ants and bees share most of their genes with the queen, so helping her helps their genes propagate.

That doesn't explain why people often help friends or other non-relatives. There, altruism usually incurs some benefit, said Trivers. Friends do nice things in return. Being a good citizen allows you benefits of being part of the group.

That didn't always go over well with people, Trivers said. When he taught at Harvard in the 1970s, one student told him he didn't want to live in a world where altruism had such strings attached.

A less depressing view comes from Binghamton's Wilson, who argues that there's another force at play - group selection. When different groups of creatures are competing, some groups will survive while others go extinct. In some cases, those groups that cooperate survive better.

Group selection once stood as a mainstream idea, but it fell out of favor, he said. He believes it goes a long way toward explaining why we humans can achieve so much by working together. "Once you add that layer, you begin to see how altruism could evolve," he said.

Other biologists say that while group selection might happen in a few circumstances, they dismiss the notion that it explains much about human behavior.

Still, the idea got a recent boost from a group of biologists at Harvard. Earlier this year, they published a paper in the journal Nature that used a combination of game theory and other mathematics to explain cooperation.

That paper, whose authors included the renowned biologist E.O. Wilson, attacks the currently favored use of "kin selection" to explain altruism, replacing it with a different combination of evolutionary processes, including group selection.

In response, 139 other biologists cooperated on a rebuttal.

Several said that the paper mischaracterized the mainstream view - that the authors were attacking a "straw man" as Oxford's West put it.

Whichever idea comes out on top, it won't change the answer to our original question - whether society is tampering with evolution's course by using public money to help "unfit" people.

Both sides argue that sympathy and cooperation came about as products of evolution - part of our nature along with selfishness and greed. The scientists differ only on how we got that way.


Contact staff writer Faye Flam at 215-854-4977 or