It is reasonable to see exchange in primate groups and later in human groups as the precursor of trade. Exchange is driven by reciprocity, which originated before humans evolved, perhaps in primate groups, or even earlier. Among chimpanzees, food sharing is prevalent. Males exchange food for social benefits, including sex with receptive females, and appear to have deliberately constructed the exchanges.
Ridley describes research carried out by Frans de Waal 4 at the Yerkes Primate Center in Atlanta, in which reciprocity is the order of the day: 'If A often gives foliage to B, then B will often give to A. There is a pattern of turn-taking: A is more likely to give food to B if B has groomed A recently, but not if A has done the grooming favour. A chimp will punish another that has been stingy by attacking it.' To de Waal all this implies that chimpanzees possess a concept of trade.
Hunter-gatherer tribes display the same behaviour, but on an expanded canvas. Individuals choose to kill large animals which are far beyond the capacity of themselves or their immediate family to consume, with the purpose of exchanging the surplus meat for a variety of social goods, including prestige, sex, expectation of future food, repayment of past favours, payment in advance for future favours, and so on.
Says Ridley: 'I do not believe it is too far-fetched to see in the actions of hunter-gatherers distant echoes of the origins of modern markets in financial derivatives'. According to Hill and Kaplan 5 the hunter is entering into a contract to swap the variable rate return on his hunting effort for a more nearly fixed return rate achieved by his whole group.
4 F B M de Waal, Journal of Human Evolution, 18: 433-459, 1989
5 Hill and Kaplan, Population and dry-season subsistence strategies of the recently contacted Yora of Peru, National Geographic Research, 5: 317-334