How CHIMPANZEE got so kind

Chimpanzees have shown they can help strangers at personal cost without apparent expectation of personal gain, a level of selfless behavior often claimed as unique to humans.
These new findings could shed light on the evolution of such altruism, researchers said.
Scientists think altruism evolved to help either kin or those willing and able of returning the favor — to help either one's genetic heritage or oneself. Humans, on the other hand, occasionally help strangers without apparent benefit for themselves, sometimes at great cost.

There is a biological predisposition to altruistic tendencies that we share with our common ancestor, and culture cultivates rather than implants the roots of altruism in the human psyche from primordial forms to more mature ones," Warneken told LiveScience.

Storyteller: Felix Warneken psychologist, Max Planck Institute for Evolutionary Anthropology at Leipzig, Germany.