 Sceptics might think there must surely be phenomena in complex animals, such as humans, that resist such modelling. They might suggest that cognitive activities are something that simply cannot be modelled by microbes of any kind because there is no basic analogue with which to work. But even for cognition, unicellular organisms have been extensively studied for decision optimization, efficiency calculations, memory, anticipation and self-awareness (Westerhoff et al. 2014; Beekman &amp; Latty 2015). Not only do these microbes (eukaryotic and prokaryotic) undergo direct examination for their own cognitive capacities, but they also stand in for the more complex and hard-to-access capacities of organisms such as animals. Again, the claim here is not that microbes’ cognitive capacities are the same as those of animals. The claim is that microbes have capacities that include key aspects of cognition, and these capacities can be studied as analogues for cognition in general (including cognition in animals). Just as for kin recognition, the quest to understand the underlying foundations of cognition makes microorganisms such as slime moulds and E. coli valuable models for cognitive capacities of a general kind that are not dependent on brains (Beekman &amp; Latty 2015; Allen 2017). Whether this is best discussed as minimal cognition (e.g., Godfrey-Smith 2016; see Lyon forthcoming for criticism) or as another facet of a general capacity that is diversely distributed across the tree of life (e.g., Allen 2017) is irrelevant here: the point is simply that an examination of microbial research can challenge, enrich and potentially reform how philosophers think about classic subjects. Indeed, some new research in microbiology, which we turn to in Section 5, even claims that microbes in the human body are influencing the mind.