No Good Deed

I have always beleived that no one does anything that she doesn't get something out of, and now there's research to support my misanthropic conclusions. The New York Times reports:

The selfishness may just be part of our wiring. Biologists were long stumped by altruism in animals because it didn't seem to make evolutionary sense. Creatures like the altruistic vampire bat, it was theorized, would eventually be wiped out of the gene pool because forgoing consumption to aid a fellow in need would reduce their own chance of survival and reproduction. This would leave only selfish bats.

But biologists have found that this only appears to be a paradox. They observed that altruistic animals tend to be more helpful with their own family or clan, which have a higher chance of sharing these altruistic genes. Researchers also found that altruistic animals engage in tit-for-tat strategies: generous to those who are generous back, but withholding from the selfish.