Could Plants Be Sentient?

Abstract

Feelings in humans are mental states representing groups of physiological functions that usually have defined behavioural objectives or purpose. Feelings are thought to be coordinated in the brain stem of animals and are evolutionarily ancient. One function of the brain is to prioritise between competing mental states, and thus groups of physiological functions and in turn behaviour. Anger, fear or pain call for immediate action whereas hunger, or thirst, signify longer term needs and a requirement for search. Plants use groups of coordinated physiological activities to deal with defined environmental situations but currently have no known mental state to prioritise any order of response. Plants do have a nervous system based on phloem which is highly cross linked. Its potential for forming a mental state is unknown but it could be used to distinguish between different and even contradictory signals and thus determine a priority of response. The vascular nervous system stretches throughout the whole plant providing the potential for assessment in all parts and commensurate with its self-organising, phenotypically plastic behaviour.