Do Plants Behave Like Animals?

Do Plants Behave Like Animals?
Do Plants Behave Like Animals?
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Your daffodils don't care what you have to say. They aren't uplifted by Mozart's symphonies. They don't feel pain when being pruned.

These myths originally reached the mainstream with the book The Secret Life of Plants, which later became a feature documentary. Occult author Peter Tompkins told readers that plants might very well be sentient. To support his claim, he cited a polygraph expert attesting that his lie detector test caught sparks of activity in plants exposed to various stimuli, including subtle threats. Tompkins also referenced a crank scientist who claimed that he had detected plant consciousness and also found that mustard seeds could receive interstellar signals from the cosmos, perhaps from plants on distant worlds.

The scientific community brutally panned Tompkins' work, but the public ate it up. Soon, gardeners all over the world were reading to their plants and playing them classical music. Oddly enough, subsequent studies actually showed that these tactics may boost plant growth, but not because seedlings enjoy a soothing voice. Sound waves cause vibration, and this vibration seems to trigger a beneficial response via a yet unknown mechanism. Sunlight, water, and nutrients matter much, much more to a plant's wellbeing, however.

Decades after The Secret Life of Plants, there's a more nuanced scientific debate going on: do plants behave the same way that animals do?

There's no doubt that plants do some amazing things. When being eaten by caterpillars, cotton plants release signals that attract insect-eating parasitic wasps to attack the caterpillars. Bean plants in close proximity to each other seem to communicate if one is under attack. Bean plants connected by symbiotic fungus will raise their chemical defenses if a compatriot is besieged by aphids. Mimosa plants even seem to have a basic memory. While the sensitive plants usually curl up when touched or dropped, scientist Monica Gagliano got them to ditch their regular response by repeatedly exposing them to a harmless six-inch fall to a cushioned surface.

All of these feats are that much more incredible given that plants lack the same vision, hearing, and brains enjoyed by animals. They're also firmly rooted and move much more slowly. These inherent inhibitions to plants also limit scientists' abilities to make conclusions about their activities. Without brains, can plants truly behave?

This makes the debate over plant behavior and intelligence more semantic and philosophical than strictly scientific. What constitutes behavior? What constitutes intelligence? This is a debate that's been ongoing for hundreds of years. Erasmus Darwin, grandfather to Charles Darwin, argued that plants acted of their own volition. Most of his contemporaries disagreed, contending that their actions are simple reflexive, programmed responses.

These questions may never receive conclusive answers, making the plant behavior debate irresolvable. Plant behaviorists would love to draw attention to their field and see plants elevated to the same plane as animals. Skeptical botanists would prefer not to make hyperbolic statements that go beyond what can be concluded with observational evidence.

Both sides can agree that plants are wonderful, complex organisms integral to life as we know it on Earth.

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