Humans clearly demonstrate altruistic tendencies towards other members of groups with which they identify.
One bit of evidence that this is innate comes from studies with oxytocin. Those who inhale the hormone are significantly more likely to sacrifice for the benefit of members of their own groups, but show no increased inclination to help members in other groups.
Dutch men high on oxytocin, for example, are inclined to help out other Dutch men more than otherwise, but not inclined to help out Muslims.
Other evidence comes from the prevalence of religious sects. Religious types give far more time and money to charity than heathens—not just to religious causes, but to all causes. But it turns out not to be religious beliefs that matter, rather it's how much time these people spend with members of the religious groups with which they identify—how often they go to church. Yes, they are believers, but only as a means of rationalizing their self-sacrificing behavior.
Indeed, Richard Sosis examined 200 19th century U.S. communes and found that 39% of religious communes, but only 6% of secular communes, survived for 20 years. The key to survival in these religious communes was evidently requiring members to sacrifice individual pleasures. This did not matter in secular communes, presumably because secular communes do not postulate the existence of a God necessary to justify the requisite sacrifices.
But whence comes this tendency to sacrifice oneself for the good of a group? To survive we have had to compete with other groups for resources necessary for propagation, namely food and eggs. And indeed, archaeological and ethnographic evidence show that historically humans had a significant chance (around 10%) of dying in warfare.
Obviously such a high mortality rate resulted in tremendous evolutionary pressure.
Those groups in which individuals sacrificed for the good of the group out-competed other groups. So there was pressure on individuals to act altruistically.
Of course, there also had to be some method of preventing free riders, and so we evolved with a tendency to punish those who do not act altruistically.
Morality and religion are thus evolutionary by-products of war.
- "The Righteous Mind" by Jonathan Haidt, pages 234-267
- "Did Warfare Among Ancestral Hunter-Gathers Affect the Evolution of Human Social Behavior", 2009 article by Samuel Bowels in Science
- "Group Competition, Reproductive Leveling, and the Evolution of Human Altrusim", 2006 article by Samuel Bowles in Science
- "The Neuropeptide Oxytocin Regulates Parochail Altrusim in Intergroup Conflic Among Humans", 2010 article by De Dreu, Greer, Handgraaf, Shalvi, Van Kleef, & Bass, in Science
- "Oxytocin Promoste Human Ethnocentrism" 2011 article by by De Dreu, Greer, Handgraaf, Shalvi, & Van Kleef, in Proceedings of U.S. National Academy of the Sciences
- "Bowling Alone: The Collapse and Revival of American Community" 2001 book by Robert Putnam
- "American Grace: How Religion Divides and Unites Us", 2012 book by Robert Putnam and David Campbell
- "Cooperation and Commune Longevity: A Test of the Costly Signaling Theory of Religion", 2003 article by Richard Sosis and Eric Bressler
- "Religion as an Evolutionary Byproduct: A Critique of the Standard Model", 2012 article by Russell Powell and Steve Clarke
Photo from "The Pacific" by HBO