A study shows that social roles are not solely dependent on individual predispositions. They are therefore not fixed, but dynamic and very flexible, allowing each individual to change roles when the system in which they operate transforms. Communiqué
In animal societies as in human societies, we regularly observe individuals who produce resources and others who capture them. Contrary to what evolutionary theories (1) may have previously suggested, these social roles are not solely dependent on individual predispositions. On the contrary, according to a study carried out in mice by scientists from the CNRS (2) and Sorbonne University, their distribution and stabilization in groups of individuals emerge from a collective dynamic based on the chance of initial interactions and on learning. Social roles are therefore not fixed, but dynamic and very flexible, allowing each individual to change roles when the system in which they operate is transformed. These results, published in the journal Naturethe 1is April, are based on the analysis of the roles assumed by mice in a semi-natural environment where food is obtained by pressing a lever.
By distinguishing between individuals adopting the behavior of “producers”, producing more than they consume, “profiteers”, consuming more than they produce, and “accumulators”, who consume in a balanced manner, the research team surprisingly demonstrated that in the groups of mice studied, the distribution of social roles is based on different dynamics between groups of opposite sexes. While a division of labor based on competition is established in groups of males, groups of females remain, on the contrary, remarkably homogeneous, without specialization taking hold: each individual adopts similar behavior, without seeking to exploit the resources produced by its peers. On the other hand, the introduction of a single male into a group of females can be enough to push the latter towards competitive behavior.
At the brain level, scientists have observed that dopamine accompanies the stabilization of social roles : a peak in the activity of these molecules, involved in learning through reward (3), is noted in “producer” individuals during their own action on the lever allowing them to obtain food, while in “profiteers” this peak is identified when another individual uses this same lever. Dopamine does not define the social role adopted by individuals, but it constitutes the mechanism by which group dynamics consolidate a role that the experience of the first interactions has initiated.
Notes
- Evolutionary theories have long treated this phenomenon as a stable balance between strategies, which can give the impression that roles are predefined.
- Working at the “Brain Plasticity” laboratory (CNRS/ESPCI PARIS – PSL) and at the Institute of Intelligent Systems and Robotics (CNRS/Sorbonne University), as well as at the Institute of Functional Genomics (CNRS/Inserm/University of Montpellier) and at the “Genes, synapses and cognition” laboratory (CNRS/Institut Pasteur).
- Dopamine does not directly trigger happiness, but participates in the anticipation of reward.
Bibliography
Dopaminergic mechanisms of dynamical social specialization. C. Solié, A. Nicolson, R. Justo, Y. Layadi, B. Morin, C. Batifol, LM Reynolds, T. Le Borgne, SL Fayad, A. Gulmez, Y. Rodriguez Quevedo, J. Allegret-Vautrot, G. Centene Guglielmi, F. de Chaumont, S. Didienne, N. Debray, JP. Hardelin, B. Girard, A. Mourot, J. Naudé, C. Viollet, F. Marti, B. Delord et P. Faure. Naturethe 1is avril 2026.
Press release, CNRS, April 1, 2026
