The origins of human variation in human economic behaviour: Comparative studies of other primates can help disentangle the relative role of shared biological processes vs human-unique cultural influences in risk preferences

Variation in primate decision-making under uncertainty and the roots of human economic behaviour. Francesca De Petrillo and Alexandra G. Rosati. Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 376, Issue 1819, January 11 2021. https://doi.org/10.1098/rstb.2019.0671

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348516690167029766

Abstract: Uncertainty is a ubiquitous component of human economic behaviour, yet people can vary in their preferences for risk across populations, individuals and different points in time. As uncertainty also characterizes many aspects of animal decision-making, comparative research can help evaluate different potential mechanisms that generate this variation, including the role of biological differences or maturational change versus cultural learning, as well as identify human-unique components of economic decision-making. Here, we examine decision-making under risk across non-human primates, our closest relatives. We first review theoretical approaches and current methods for understanding decision-making in animals. We then assess the current evidence for variation in animal preferences between species and populations, between individuals based on personality, sex and age, and finally, between different contexts and individual states. We then use these primate data to evaluate the processes that can shape human decision-making strategies and identify the primate foundations of human economic behaviour.

5. Conclusion: primate decision-making and human economic origins

Humans exhibit great variation in responses to risk across populations, individuals and contexts, so understanding the origins of this variation is crucial to explaining patterns of human economic behaviour. We have argued that comparative studies of decision-making can disentangle the mechanisms and the function of this variation to address questions about both the proximate mechanisms and the ultimate consequences of these decision-making patterns. As such, non-human primates provide a complementary line of evidence to test hypotheses about the origins of human economic behaviours (figure 2).

Figure 2. The origins of human variation in human economic behaviour. Comparative studies of other primates can help disentangle the relative role of shared biological processes versus human-unique cultural influences in risk preferences. Current evidence for variation across populations, individuals and contexts in primates suggests some processes are shared with humans whereas others are human-unique.

We found that non-humans sometimes show patterns of variation like those in humans. For example, emotional states, social context and some neurotransmitter systems can modulate risk preferences in primates like in humans. This suggests that at least some of the proximate psychological mechanisms driving human economic behaviour build upon cognitive, emotional and neurobiological substrates that are shared with other primates Yet other mechanisms may be more specific to humans: while humans show robust gender differences in risk preferences as well as developmental change over the life-course, there is limited evidence for parallel shifts in non-human risky choice. This suggests that this variation may stem more from human-specific mechanisms, such as cultural learning and socialization. Given that culturally based traits are more malleable and thus more amenable to interventions, this provides new clues for promoting optimal economic behaviour in humans.

A second question concerns the ultimate consequences of variation in risk preferences. Here, comparative work can provide an important line of evidence to test the adaptive consequences of different strategies. For example, there are robust species differences in responses to risk indicating that species that typically feed on more variable, heterogeneous resources are relatively more risk-seeking. Yet there are also crucial differences in human and animal patterns that may stem from humans' novel socioecological niche. Human hunter–gatherer lifestyles are characterized by a dependence on high-value and high-risk foods that may have required new social mechanisms to cope with a greater variability in foraging, such as food sharing and resource redistribution [107,116]. As a consequence, humans might have evolved new cognitive abilities and innovated new cultural practices to deal with the social risks presented by exchanges.

Yet there is still much work to be done. First, different species and questions have sometimes been tested using different tasks (figure 1), limiting some inferences across studies. In addition, primate studies, in general, are often limited by small sample sizes, especially with respect to questions of intra-individual variation. As such, comparisons of decision-making using standardized methods in larger populations with wider variation in sex, ages or particular life experiences are crucial to test these ideas. Finally, the animal choice typically involves biologically relevant rewards, but there is increasing evidence that people can be more risk-seeking when making ‘foraging’ decisions about food than in equivalent decisions involving money [67,103]. Given that humans engage in evolutionarily novel forms of economic exchange involving abstract currencies, but other primates can be trained to use and exchange tokens in specific contexts [84], animals thus present untapped opportunities to test how experience with markets impacts economic decision-making. More generally, comparative research is well-positioned to advance our understanding of human economic behaviour by pinpointing the necessary cognitive and experiential prerequisites that enable different aspects of decision-making and exchange.