[troutman]

Fascinating topic.

http://endeavor.med.nyu.edu/~strone01/altruism.html

Despite the overwhelming success Darwin’s theory has had in explaining a wide variety of natural phenomena, great debate continues over the theory’s application in explaining the evolution of an aspect of animal behavior known as altruism.

If, by definition, altruism reduces an individual’s fitness, we should expect Darwin’s natural selection to select against the altruistic trait and eventually reduce its representation within a population to zero. Even if a population existed that contained only altruists from the beginning, it would be vulnerable to subversion from within, whereby a single, mutant selfish individual could exploit the altruistic tendencies of his neighbors and eventually drive the altruistic trait to extinction.

Although the problem of altruism was largely ignored by early evolutionary theory, over the past several decades it has risen to become a central issue in the debate over the level at which natural selection operates - whether that be the level of the gene, individual, kin group, or even an entire population. Numerous theories have been proposed to explain this phenomenon, several of which are discussed below.

http://news.bbc.co.uk/1/hi/sci/tech/4766490.stm

Infants as young as 18 months show altruistic behaviour, suggesting humans have a natural tendency to be helpful, German researchers have discovered.

In experiments reported in the journal Science, toddlers helped strangers complete tasks such as stacking books.

Young chimps did the same, providing the first direct evidence of altruism in non-human primates. Altruism may have evolved six million years ago in the common ancestor of chimps and humans, the study suggests.