They can communicate with each other about threats, summon help from predatory killers – and some can even count – but does this mean plants are conscious?
Last month, at a gathering at New York University, a group of prominent biologists and philosophers widened the perimeter of a very exclusive club. They declared that there is “a realistic possibility” that insects, crustaceans and fish experience consciousness. This was an expansion of an earlier declaration, made in 2012, in which researchers asserted that mammals and birds were capable of intentional behaviour and had all the physical markers of conscious states: “Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness,” they concluded. The official consciousness list – or “realistic possibility of consciousness” list – now includes “all vertebrates (including all reptiles, amphibians and fishes) and many invertebrates (including, at minimum, cephalopod mollusks, decapod crustaceans and insects)”.
Lizards have been shown to learn how to navigate mazes, suggesting behavioural flexibility, an often-used marker of intelligence. Bees are able to distinguish between styles of art; engage in play; and perform an elaborate, symbolically rich “waggle dance” that tells their hive mates precisely how far and at what angle to the sun to fly to find food. Scientists suggest bees may have the capacity to feel, perhaps denoting consciousness.
