Brains and where else? Mapping theories of consciousness to unconventional embodiments

It is assumed that a useful theory of consciousness (ToC) will explain why consciousness is associated with brains. However, the findings of evolutionary biology, developmental bioelectricity and synthetic bioengineering reveal ancient pre-neural roots of many mechanisms and algorithms occurring in brains: minds may have preceded brains. Most work in the emerging field of diverse intelligence emphasizes externally observable problem-solving competencies in unconventional media, such as cells, tissues and life-technology chimeras. Here, we inquire about the implications of these developments for ToCs. Specifically, we analyse popular current ToCs to ask: What features of each theory specifically pick out brains as a privileged substrate of inner perspective, or do the features emphasized by the theory occur elsewhere? We find that the operations and functional principles of most ToCs are not confined to neural substrates, and that the focus on brains is more driven by convention than by the specific content of existing ToCs. Encouragingly, several contemporary theorists have made explicit efforts to apply their theories to synthetic systems in light of recent technological developments in artificial intelligence and organoid bioengineering. We suggest that the science of consciousness should remain open to minds in unconventional embodiments. This article is part of the theme issue 'World models in natural and artificial intelligence'.