Data and code accompanying the manuscript: Van Baar, J., Klaassen, F.H., Ricci, F., Chang, L., & Sanfey, A.G. (2020). Stable distribution of reciprocity motives in a population. Scientific Reports. doi: 10.1038/s41598-020-74818-y. www.nature.com/articles/s41598-020-74818-y