Chimpanzees more rational than humans?

In news that shouldn’t surprise anyone, German researchers at the Max Planck Institute of Evolutionary Anthropology found that chimpanzees choose more "rationally" than humans - if by "rationally" you mean that, in a reward game,

Humans typically make offers close to 50 percent of the reward. They also reject as unfair offers of significantly less than half of the reward, even though this choice means they get nothing.

The study, however, showed chimpanzees reliably made offers of substantially less than 50 percent, and accepted offers of any size, no matter how small.

The researchers concluded both that chimpanzees do not show a willingness to make fair offers and reject unfair ones. In this way, they protect their self interest and are unwilling to pay a cost to punish someone they perceive as unfair.

The study (published in Science, October 5, 2007) continues in the well-worn path of trying to derive human behavior from primate ape behavior, and when that doesn’t work, the outcome is supposed to be something of a surprise.

Why? Humans often assign values other than the expected ones, have specific ideas about what's fair, and prefer emotional satisfactions to other types. Don't believe me, believe Woody Allen.