Donnerstag, 24. Mai 2007

"Evolutionary biology's version of e = mc2"

Here is a little piece of Lee Alan Dugatkin about his newest book concerning the evolution of altruism. (Huffingtonpost)

As long as there have been scientists, they have been interested in goodness. Why are some people good, and others not? In fact, we can cast the net more generally, and ask about goodness in nonhumans, as well as humans, and examine whether the process of evolution by natural selection can explain such actions.

I talk about this at length in my new book, The Altruism Equation: Seven Scientists Search for the Origins of Goodness (Princeton University Press, 2006), but here is a condensed version of the story. Evolutionary biology's interest in goodness can be traced back at least as far as Charles Darwin. (...)

It would take almost a hundred years before a shy, reserved, and brilliant British biologist named William D. Hamilton would settle all the arguments about blood kinship and altruism with a nifty little mathematical equation.

Hamilton, an evolutionary biologist by training, came at the question of altruism and blood kinship the way that an economist would; indeed his Ph.D. in biology was done in part at The London School of Economics. He began by defining three terms─the genetic relatedness between individuals (labeled r), the cost of an act of goodness (c), and the benefit that a recipient obtained when someone was nice to him or her. Then, using some eloquent--in fact, beautiful-- mathematics, in 1963, Hamilton found that altruism and blood kinship are not linked by an all-or-nothing relationship. Instead, what is now known as "Hamilton's Rule" states that altruism evolves whenever r times b is greater than c. In other words, if the cost of altruism is made up by enough genetic relatives receiving benefits, then altruism spreads; otherwise it does not. Phrased in the cold language of natural selection, relatives are worth helping in direct proportion to their genetic relatedness.

Literally thousands of experiments in both nonhumans and humans show the power of Hamilton's Rule. This little equation is evolutionary biology's version of e = mc2. Over and over, we see that an analysis of the costs and benefits of altruism, along with genetic relatedness, allows us to predict the presence or absence of altruism. This is a truly remarkable finding.

Hamilton's Rule, of course, does not explain all altruism, nor did Bill Hamilton think it did. Another large chunk of goodness falls under the category of reciprocity--you scratch my back, and I'll scratch yours. Individuals are sometimes willing to be altruistic to someone now in the expectation that they will, in turn, be helped when they need it. Evolutionary biologists have been almost as interested in this type of altruism as in kinship-based altruism. And, amazingly enough, it was Bill Hamilton, along with political scientist Robert Axelrod, who formalized the models behind the evolution of reciprocity. Following up on some work done by Robert Trivers in the early 1970s, in 1981 Axelrod and Hamilton used a mathematical technique called game theory to predict when "reciprocal altruism" should evolve. Again, scores of empirical studies followed up the model. Reciprocity can be complex, but an evolutionary perspective has cleared the haze here the same way it did when it came to blood kinship and altruism.

If goodness is a problem, then the answer─or at the very least, part of the answer─can be found in evolutionary biology.

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