By focusing on the studies of primate behaviour and human neuroscience, we describe how different neurological processes are the base of proximate aspects of social-decision making. We also review the fact that distinct aspects of animal behaviour are not under conscious or abstract control and that instead they may be regulated by adaptive ´rules of thumb´. In particular, by describing the microbiota- gut-brain axis we elaborate on suggesting that microbiota has an influence on within-individual aspects of social decision making and in particular facilitating social interactions. Finally, we present comparative evidence of the role of microorganisms as modifiers of aspects of kinship, reproduction and group-members´ recognition, suggesting how microbiota also has an influence on betweenindividual aspects of decision making, which are themselves primary aspects of cooperation. In summary, we propose that modern socioeconomic choice theories may still benefit from alternative theoretical frameworks that consider the human being as a complex organism, with intrinsic constraints and capacities product of its evolutionary history, and not just as an exclusively-cognitive decision maker acting independently of its closest partners and commensals: its microbiota.
Keywords: Neuroeconomics, microbiota, probiotics, decision making process, social neurosciences.