One anthropologist is trying to understand the evolution of a class system in pre-agricultural societies. He's studying a fish-forager society at Keatley Creek, British Columbia. This, in turn, tells us, something about how agricultural societies must have evolved all around the world:
Nomadic hunter-gatherers were essentially egalitarian. They lived at a subsistence level, with starvation only the next drought away. Resources were shared, because sharing maximizes the chances of survival for the group as a whole. Hoarding—co-opting resources for private use—was socially unacceptable. Individual ambition was suppressed, because it would disrupt the group cohesion necessary for survival. Economic competition didn’t exist.
The combination of the Fraser River’s abundant salmon and consistent warm winds to dry caught fish made the Keatley Creek location a key fishing location for thousands of years and into the present.
About 40,000 years ago humans began developing more complex tools and behaviors, and about 10,000 years ago, agriculture and animal domestication. For a long time researchers believed that these latter innovations, by greatly increasing the volume, reliability, and storability of food resources, were prerequisites for the development of socioeconomic inequality. However, the people of Keatley Creek still made their living by hunting, foraging, and most importantly for this story, fishing. They didn’t have agriculture or domesticated animals, except for dogs. What spurred the rise of inequality in that setting?The Evolution of Fairness (Pacific Standard) See also: The Roots of Social Inequality (University of Montana) And:
A key factor seems to have been salmon, which are abundant in the Fraser River. They are readily preserved by drying, and warm winds during the fishing season provide an ideal natural dehydrator. Salmon provided a reliable surplus of storable food that enabled the people of Keatley Creek to settle, eventually building a village where they could hunker down for the cold, dark winter of the British Columbia interior and still have enough to eat.
Brian’s work led him to a theory of how the people of Keatley Creek evolved strategies for sharing this bounty, and in the conclusion, we investigate its implications for the challenges of inequality today.
The Gospel of Wealth Fails the Inequality Test in Primates (Scientific American)
But I'm not sure looking at chimpanzees and orangutangs tells you anything. Neither do hunter-gatherers. Once humans were able to store surpluses, it became survival of the richest - those on the top survived, as did those who obeyed those at the top. Egalitarianism was probably slowly bred out of the human genome during the course of agriculture (similar to the introduction of lactose tolerance and oxygen processing at high altitudes). Greed became optimal for evolutionary fitness, and those who didn't like it were slowly culled.