The debate on biological individuality has usually been focused on the definition and characterization of evolutionary individuals. Addressing this topic has helped clarify the discussion about units of selection and the requirements for evolution by natural selection. Less attention has been paid to other kinds of individuality (i.e. non-evolutionary based accounts), among which the main alternative to evolution to ground biological individuality has been constituted by organismal physiology. Non-evolutionary accounts of biological individuality are still underdeveloped in comparison to evolutionary ones. This is especially evident in relation to interactive cases (i.e. host-microbe symbioses, microbe-microbe symbioses (biofilms), colonies,) that transcend the “traditional organism”.

On the one hand the very notion of organism has been challenged by cases of cohesive entities emerging from interactions. Recent research on host-microbiota and, more generally, symbiotic relationships characterized by close functional ties, for example, might seem either to question the possibility to establish clear functional boundaries for living organisms, or to call for further work of characterization of the different ways functional interactions can be establish within a system or between systems. On the other hand, where generalization has been attempted, criteria involved in physiology, metabolism, organisms, anatomy, and ecology all tend to get bundled up together with very few distinctions to be made about why they go together.

The need for precise accounts based on conceptual or theoretical criteria is therefore especially apparent given new understandings of a wide range of interactive biological entities, from different types of multicellular systems to host-microbe interactions. The possibilities of forms of biological individuals arising out of interactions and new ways to identify and account for non-evolutionary individuals will be explored by focusing on physiology from an organizational perspective (or biological autonomy framework). At the same time this work will address the challenges represented by research on interacting entities, which seems to question the application of very notions of autonomy and individuality in biology.

To develop this framework on individuality, I will lean on previous work on control mechanisms, considered as those components of biological systems that are responsible for coordinating, modulating, activating and inhibiting the activities of other components in such a way as to maintain the overall viability of the biological system that harbours them. This is a step forward with respect to previous developments the organizational account, mainly focused on how a living system maintains itself by producing its parts. This approach will be applied to two case-studies: multicellular organizations and holobionts (in collaboration with Derek Skillings, UNCG).