Michael Griesser, Nigel C Bennett, Judith M Burkart, Daniel W Hart, Natalie Uomini, Miyako H Warrington

Cooperation is a pivotal biological phenomenon that occurs in many forms. In species that engage in helping, individuals vary in association time and the extent of physical proximity, influencing the extent of touching between individuals. Here, we emphasize the importance of touch in the development and maintenance of parenting and mate bonds, and its link to cooperation. Touch activates a feedback loop via social hormones that supports bonds in general. Notably, extended parenting is crucial for the emergence of enduring bonds and the development of the mindset that supports investments which result in delayed benefits. We integrate these ideas in the ‘caring-touch’ hypothesis, highlighting the role of touch and enduring bonds in the evolution of different forms of cooperation.