Do plants feel pain? | The Economist

Non-neural intelligence mechanisms:

• Biologist Michael Levin demonstrated that neuronal-like behaviors can occur without neurons, relying on bioelectric fields to store and process information.
• These bioelectric fields hold information in the body rather than a centralized brain, as evidenced by planaria worms retaining conditioned lessons after their heads were chopped off and regrown.
• The hypothesis posits that "neurons are overrated" and that any cell can perform computation, though plant responses are significantly slower than animal neural processing.

Documented plant sensory and behavioral capabilities:

• Visual mimicry: Vines alter leaf morphology to mimic the specific leaf shape of the host plant they are climbing.
• Auditory detection: Plants release toxins upon hearing the sound of caterpillar chewing and locate water sources by sensing the sound of water in pipes.
• Echolocation hypothesis: Bean plants perform circumnutation (spiral motion) to locate poles, potentially using sound reflection similar to bat echolocation.
• Anesthetic response: Venus flytraps cease responding to stimuli when exposed to surgical anesthetics (e.g., xenon gas), suggesting a loss of sentience comparable to human unconsciousness.

Memory and conditioning studies:

• Mimosa pudica (sensitive plant) can be conditioned to stop reacting to a shaking stimulus after repeated non-threatening exposures.
• This conditioned behavior is retained for up to 28 days.

Distinction between sentience, consciousness, and intelligence:

• Experts distinguish between "consciousness" (implying self-awareness or interiority) and "sentience" (awareness of the environment), preferring the latter for plants.
• Plant intelligence is defined as "problem-solving intelligence" necessary to navigate unpredictable environments rather than human-style cognitive reasoning.
• Evolution favors problem-solving capabilities over fixed DNA programming because environments are too dynamic to pre-program every contingency.

Debates on plant pain and morality:

• Disagreement on pain perception:
  • One neurobiologist argues plants likely feel pain.
  • Another argues pain is non-adaptive for immobile organisms, as pain functions to drive avoidance behavior which plants cannot perform; instead, plants are simply "aware" of being eaten.
• Moral and dietary implications:
  • Plants co-evolved with herbivores; many rely on being eaten to spread seeds, and grasses regenerate after grazing.
  • The consensus among interviewed experts suggests eating plants does not constitute moral transgression regarding pain, as pain is not a necessary or adaptive trait for stationary flora.