Evolution and impact of socially transferred materials

Since the dawn of life, transfers of metabolized material between individuals have led to great innovations of evolution. When metabolized material is transferred from one individual’s body to another (as with sperm, eggs, milk, symbionts), secondary manipulative molecules that induce a physiological response in the receiver are often transferred along with the primary cargo. The bioactive and transfer-supporting components in these socially transferred materials have evolved convergently to the point where they can be used in applications across taxa and type of transfer. Because these materials’ composition is typically highly dynamic and context-dependent, their focused study will allow deeper understanding of their transformative evolutionary and physiological role. We synthesize a conceptual framework for their study, and discuss future directions.