The adaptive value of probability distortion and risk-seeking in macaques' decision-making

In humans, the attitude toward risk is not neutral and is dissimilar between bets involving gains and bets involving losses. The existence and prevalence of these decision features in non-human primates are unclear. In addition, only a few studies have tried to simulate the evolution of agents based on their attitude toward risk. Therefore, we still ignore to which extent Prospect theory's claims are evolutionary rooted. To shed light on this issue, we collected data in 9 macaques that performed bets involving gains or losses. We confirmed that their overall behaviour is coherent with Prospect theory's claims. In parallel, we used a genetic algorithm to simulate the evolution of a population of agents across several generations. We showed that the algorithm selects progressively agents that exhibit risk-seeking and an inverted S-shape distorted perception of probability. We compared these two results and found that monkeys' attitude toward risk when facing losses only is congruent with the simulation. This result is consistent with the idea that gambling in the loss domain is analogous to deciding in a context of life-threatening challenges where a certain level of risk-seeking behaviours and probability distortions may be adaptive.