Despite decades of research into the subject, no agreement exists about where cognition is found in the living world. Is a nervous system needed? If so, why? If not, why not? This two-part theme issue on the emerging field of ‘Basal Cognition’ pursues Darwin’s insight that life’s ‘mental faculties’ evolved early with physical embodiment and in parallel with it. Articles in Part 1 (Conceptual tools and the view from the single cell) range from molecules to unicellulars (bacteria, amoeba, slime moulds). Part 2 (Multicellularity, neurons and the cognitive lens) addresses plants, the neural revolution and cognitive cellular behaviour in development and regeneration. A working definition of cognition—a rarity—provides material for endless debate.

This is the first of a two-part issue. Read the second part here.

This issue is available to buy in print. Visit our information for readers page for more purchasing options.