Theme 1: The work led to novel insights, the most fundamental one being that evolution favors "social-Kantian preferences", which combine self-interest with Kantian morality and social other-regard: when taking decisions individuals evaluate (1) own material payoff, (2) what this material payoff would be, if others selected the same action (Kantian morality), (3) how own material payoff compares to others' (other-regard).
These preferences were then tested experimentally; most participants behaved consistently with them, and we estimated the weights they attach to material self-interest, and the Kantian and other-regarding concerns.
Another experimental study shows that participants behave (i) more pro-socially when behind the veil of ignorance; (ii) less pro-socially when the task is described as a market interaction rather than in neutral terms.
This part also shows that social-Kantian preferences motivate behaviours such as paying taxes and voting: what would the final outcome be if others acted like me?
Finally, this part studies social norms. Human actions are embedded in complex social processes. Individuals form their opinions and beliefs about (1) which actions are morally right; (2) which actions others adopt; (3) which actions others perceive as being morally right; (4) the material consequences of their actions. Together, these form the society's moral, behavioral, and social norms. Theory on norms postulates "thresholds for collective behaviour": individuals are willing to make sacrifices, but only if sufficiently many others do so. We enrich this theory by showing how social-Kantian preferences lead precisely to such thresholds.
Theme 2: This led to inter-disciplinary work (with evolutionary anthropologists and biologists, and a primatologist) to advance our understanding of the evolution of behaviours that are unique to humans. It uses an evolutionary ecology approach, establishing with mathematical models possible links between the environment where a population evolves and behaviours. A similar logic can be found for preferences for food: we enjoy eating foods that in the past were beneficial for us, but experience disgust for dangerous substances. Here, this logic is applied to social behaviours. It helps explain variation in behaviours across the world. The theoretical models also help formulate novel interpretations of fossil evidence.
The work led to major breakthroughs for understanding the advent of (i) male provisioning of food to their offspring; (ii) food sharing between adult males and females. Combined with evidence of ecological change in the past, we can infer when these behaviours likely appeared in our evolutionary past. For male provisioning, we argue that it appeared in Homo erectus, around 1.8 million years ago. For food sharing between adult males and females, we argue that it appeared shortly after our ancestors managed to survive outside of the tropical rainforest, around 6 million years ago.
The grant funded inter-disciplinary conferences on:
Cultural Evolution
Fertility: Causes and Consequences
Production and Sharing
Inertia in Biological and Cultural Systems
Inequality in Networks
• Publications:
"Norms and norm change - driven by social preferences and Kantian morality" With P Bayer
"Doing the right thing (or not) in a lemons-like situation: on the role of social preferences and Kantian moral concerns" With JI Rivero-Wildemauwe
"Estimating social preferences and Kantian morality in strategic interactions" With B van Leeuwen
"Proximate and ultimate drivers of norms and norm change" With S Gavrilets and P Durkee
"Evolution of semi-Kantian preferences in two-player assortative interactions with complete and incomplete information and plasticity" With L Lehmann
"The evolution of early hominin food production and sharing" With S Dridi, J Stieglitz, M Wilson
"Evolution and Kantian morality: a correction and addendum" With JW Weibull
"Evolutionarily stable preferences"
"Evolution of preferences in group-structured populations: genes, guns, and culture" With JW Weibull and L Lehmann
"Evolution of the Family: Theory and Implications for Economics". With D Cox
"Paternal provisioning results from ecological change" With D. Cox, P. Hooper, H. Kaplan, J. Stieglitz
"Homo moralis goes to the voting booth: a new theory of voter participation" With K Dierks and JF Laslier
"Homo moralis goes to the voting booth: coordination and information aggregation" With JF Laslier
"On the evolution of male competitiveness"
• Other team members:
"Moral preferences in bargaining" By P Juan-Bartroli and E Karagözoglu
"A foundation for universalisation in games" by EM Salonia
"Taxing moral agents." by E Muñoz-Sobrado
"On injunctive norms: theory and experiments." by P Juan-Bartroli
"Evolutionarily stable networks" by P Bayer
