Investment in By-Product Benefits (Pseudo-Reciprocity) Explains the Majority of Help Provided to Non-Relatives Found in Nature

Abstract

Pseudo-reciprocity, or investment in byproduct benefits, was introduced originally as an alternative explanation to many claims of reciprocity that followed the classic papers of Trivers and Axelrod and Hamilton. Although widely in use, the term pseudo-reciprocity has had the unfortunate effect of keeping the concept of Investment in Byproduct Benefits (IBB) in the orbit of reciprocity (reciprocal investments). A recent example is the paper by Carter (2023) linking reciprocity and pseudo-reciprocity in a continuum of ‘interdependency’ and ‘responsiveness’. As a heuristic exercise, I imagine an alternative history in which the phenomena of byproduct benefits (BB) and IBB were explored fully before the first paper on reciprocity appeared in the literature. This exercise makes clear that the simple concepts of BB and IBB, when joined with kin selection, would lead to a very reasonable description of most cases of cooperation in nature, including market effects, such as partner choice and control. Reciprocity would have claimed its rightful place as a fascinating concept, clearly important in humans and perhaps requiring specific cognitive abilities, that might emerge from the complex web of cooperation in social animals that included kin selection, BB, and IBB. In this context, continua between reciprocity and investment in byproduct benefits are useful. However, the scope for IBB is much broader than reciprocity. IBB, along with reciprocity and kin selection, is one of the key evolutionary mechanisms explaining the origin of helping behavior or ‘investment’ in others of the same and different species, occurring in many contexts where it is not usefully linked to reciprocity. Going forward, it will be helpful to remove IBB from the orbit of reciprocity by using of the term Investment in Byproduct Benefits (IBB) rather than pseudo-reciprocity.