Quote from "Our Inner Ape" by Frans De Waal (2005), which I am just about finished reading. De Waal is one of the world's leading primatologists.

I'm not trying to be preachy here, but since by coincidence I read this on heels of my last journal entry, I thought would stick it in my journal. The first paragraph I'm quoting is actually the last one in the sequence, but it makes more sense to lead with it here. From pages 195-196:

If the taste for meat is indead at the root of sharing, it is hard to sescape the conclusion that human morality is steeped in blood. When we give money to begging strangers, ship food to starving masses, or vote for measures that benefit the poor, we follow impluses shaped since our ancestors first gathered around a meat possessor........

In the wild (chimpanzees) chase monkeys until they catch one, then they tear it apart so that everyone gets a piece. The hunt I saw in the Mahale Mountains followed this pattern, with males gathered around the monkey carcass high up in the trees. The male who had captured the meat held on to it, but at some point he gave half to his best buddy, who immediately became the center of a second begging cluster. It took two hours, but by the end virtually everyone in the tree owned a piece. Females with swollen genitals (indicating fertility) were more successful than other females in getting food. And it's known among the males, hunters favor fellow hunters when dividing the meat. Even the most dominant male, if he hasn't been part of the hunting party, may stay empty-handed. This is another example of reciprocity: those who contributed to sucess have priority in the division of the spoils. Food sharing likely started as incentive for hunters to hunt another day: there can't be joint hunting without joint payoffs.

On of my favorite Gary Larson cartoons shows a group of primitive men, shovels in hand, returing from the forest carrying a giant carrot above their heads. The text reads "Early vegetarians returning from the kill." The carrot was large enough to serve the whole clan. This is profoundly ironic given how unlikely it is that vegetables played any role in the evolution of food sharing. The leaves and fruits that primates gather in the forest are too abundant and too small to share. Sharing makes sense only in relation to highly prized food that is hard to obtain and comes in amounts too large for a single individual. What is the centerpiece when people gather around the dinner table? The turkey at Thanksgiving, the pig turning on the spit, or the salad bowl? Sharing goes back to our hunting days, which explains why it is rare in other primates. The three primates best at -- that is sharing outside the family -- are humans, chimpanzees, and capuchin monkeys. All three love meat, they hunt in groups, and they share even among adult males, which makes sense given males do most of the hunting.

Of course this is just three paragraphs out of a 225 page book, and in other sections De Waal also points at child rearing as an evolutionary source for human empathy and altruism, and altruism is just one of a number of behavioral traits that De Waal explores in humans and other primates.