April 7, 2009

Why cooperative behavior doesn’t die out

U.S. researchers question how cooperative behavior, which benefits other members of a species at individual cost, continues and does not die out.

Lead author Jeff Gore, a postdoctoral fellow at the Massachusetts Institute of Technology said cooperative behavior has puzzled biologists because if only the fittest survive, genes for a behavior that benefits everybody in a population should not last and cooperative behavior should die out.

Gore is part of a team of MIT researchers that has used game theory to understand one solution yeast use to get around this problem. Game theory uses mathematics to predict individuals' behavior in certain situations.

The team's findings, published online in Nature, indicate that if an individual can benefit even slightly by cooperating, it can survive even when surrounded by individuals that don't cooperate.

Unlike humans, yeast have no emotions or thoughts that interfere with rational decision-making; their actions are solely driven by their genetic response to the environment.

The study finds that the yeast who cooperate do so because there is a slight benefit for themselves; however, when most of the yeast are cooperating, it becomes advantageous for some individuals to cheat, and vice versa, which allows co-existence between cheaters and cooperators to arise.