How humans evolved a sense of right and wrong

Adam Smith, the father of economics, was insistent that only humans could engage in market-based exchange. He famously stated that "the propensity to truck, barter, and exchange one thing for another [...] is common to all men, and to be found in no other race of animals” (Smith, 1776). In the early 1990s, evolutionary biologists began to seriously question this assumption. Through the close study of interactions among apes, monkeys and even some species of coral reef fish, they found that the law of supply and demand does not only apply to exchange among humans. Animals had their own economic markets. For example, field experiments with vervet monkeys showed that individuals with access to food that they could share in exchange for grooming would accept less grooming when the number of individuals that supplied food increased. In other words, the monkeys were lowering the “price” of food in response to an increase in supply. These and many other experiments and observations suggest that animals can have their own simple bartering economies. They don’t have cash or cards, but they do adjust the ratio at which they exchange goods or services in response to shift in supply or demand.

The discovery of market-effects in the animal world got other researchers thinking whether biological market theory might help them solve a much larger puzzle, about the origins and evolution of cooperation in humans. Could it be that market-based exchange was a stepping stone for an evolutionary dynamics of a cooperation that resulted in the emergence of the human sense of morality? A prominent line of research that draws on mathematical modelling, ethnography, behavioural ecology, experimental economics, and cognitive science has answered this question with a “yes”. This biological market theory of the evolution of morality suggests that the roots of human morality should be sought in the gradual expansion of biological markets. The simple market-based exchange that we see in our primate cousins is a pale reflection of the evolutionary basis for our much-expanded sense of morality.

Witteveen challenges this account of the evolution of morality. While he acknowledges that biological market theory is an exciting theoretical development in evolutionary biology, he shows that market effects cannot have played the all-important role in human evolution that some researchers have attributed to it. Through a combination of conceptual, theoretical and empirical analysis he shows that it is very unlikely that market dynamics played a key role in human evolution. That said, Witteveen hypothesizes that biological market effects might have played a small but significant role at a particular stage. He shows that biological market theory might hold the answer to the question why human cooperation did not break down around 100,000 years ago, when the structure of cooperation and exchange among our ancestors reached a tipping point of complexity. In sum, Witteveen argues that although biological markets don’t explain how we became moral, they might help explain why we stayed moral.

Read the article “Biological Markets, Cooperation, and the Evolution of Morality

The Oxford Think Festival

Joeri Witteveen's article has been featured at the Oxford Think Festival as one of a dozen articles highlighted to provide a fresh new perspective on science.
The Oxford Think Festival is weekend of talks and discussions in Oxford, organized by Oxford University Press in partnership with Blackwell’s Oxford. "Celebrating the quest for knowledge and seeking to stimulate discussion of some of the big issues and ideas of our time, the festival brings together some of our most inspiring and exciting minds.” Alongside the event OUP publishes a reading list of recommended philosophy articles from OUP journals.

Read more about the Oxford Think Festival