Cooperation is part of human nature, just as is competition. Under particular circumstances and given certain personality traits, one or the other will prevail. These comments are simply making the case that altruism is as natural to people as is competitiveness.
People will cooperate with one another even when they have nothing to gain. In experiments conducted by Ernst Fehr of the University of Zurich, one person is given an amount of money and then offers any amount of his or her choosing to a second person. They are told these rules: the receiver can either accept the offer, in which case the cash is shared according to the offer made, or the receiver can reject the offer, in which case neither person receives anything.
If people acted purely out of self-interest, the offers would always be low and receivers would always take what is offered. Over more than two decades, the experiments have shown that typically an offer is between 25-50% and the receiver rejects an offer of less than 25%. People offer more than necessary and reject offers that they consider too little. What seems to motivate both givers and receivers is a sense of fairness.
"The facts are clear," Fehr says. "Many people are willing to cooperate and to punish those who don't, even when no gain is possible." Such behavior, Fehr and others reason, is best explained by the fact that it leads to social cohesion. Working together had an evolutionary purpose in that it allowed our ancestors to form strong groups thereby fostering maximal survival.