The aim of this article is to propose a theorization of the father-child relationship based on our current understanding of attachment, interactions between fathers and their young children, and human-specific adaptations. The comparison of mother-child and father-child interactions suggests that fathers play a particularly important role in the development of children’s openness to the world. Men seem to have a tendency to excite, surprise, and momentarily destabilize children; they also tend to encourage children to take risks, while at the same time ensuring the latter’s safety and security, thus permitting children to learn to be braver in unfamiliar situations, as well as to stand up for themselves. But this dynamic can only be effective in the context of an emotional bond between father and child; this relationship is termed the father-child activation relationship, in contrast to the mother-child attachment relationship aimed at calming and comforting children in times of stress. The activation relationship is developed primarily through physical play. It is postulated, in particular, that father-child rough-and-tumble play encourages obedience and the development of competition skills in children.