Will plants take over the world? Apparently, it's possible...
The 2008 film by M. Night Shyamalan entitled The Happening follows a high school science teacher, his wife, and a young girl as an unprecedented crisis invades their lives.
A series of suicides and strange encounters leads the science teacher to believe that plants on the east coast are communicating with each other, triggering the release of an airborne neurotoxin which, when inhaled by a human, removes one’s self-preservation instincts.
One encounter reveals the science behind this theory:
"You know plants have the ability to target specific threats. Tobacco plants when attacked by heliothis caterpillars will send out a chemical attracting wasps to kill just those caterpillars. We don't know how plants obtain these abilities, they just evolve very rapidly…[they] have the ability to communicate with other species of plants. Trees can communicate with bushes, and bushes with grass, and everything in between." (Memorable Quotes for The Happening, 1990-2011)
The idea that plants can communicate with one another is not new. Scientists have long since known that plants emit cues that cause other organisms to change their behavior.
However, researchers are now finding that plant communication might be a bit more “human” than we thought possible.
Shyamalan’s film portrays communication among plants as hostile, and depicts the plants conspirators. For scientists, research findings demand a classification of the communication undertaken by plants.
True communication, according to Dr. Richard Karban, Professor of Entomology at the University of California, Davis, is a signal “sent with intent and interpreted accurately”. Communication theorists term this “successful communication”. However, Karban goes on to say that some animal behaviorists reserve the term “true communication” for the intentional transfer of signals that results in an increase in fitness (defined biologically as a measure of reproductive success) for both the emitter and the receiver.
In a 2008 publication in Ecology Letters, Karban reports that intent is impossible for plants and so defines plant communication as the “transfer of cues from one individual to another without any assumptions about intent or benefit for the emitter or receiver.”
Communication theorists would explain this as “accidental” communication, that is, sent without intent but interpreted accurately. However, communication theory has not yet been applied to plants.
A more general definition found in Communication in Everyday Life by Duck and McMahan describes communication as transaction: “The construction of shared meanings or understandings between two (or more) individuals”.
Current research makes it possible to argue that transactional communication takes place on a cellular level in response to environmental stimuli, between plants of related species, and between plants and their environment, including organisms that may prey on them. Simply put, plants have the ability to communicate in a transactional sense.
Cells, as life’s most basic unit, are in constant transactional communication using chemical signals. In plants, these chemical signals operate much like those in humans. The neurotransmitter acetylcholine binds to its receptor on skeletal muscles in humans, opening a sodium channel, which initiates a series of steps ultimately resulting in contraction of the muscle. Similarly, cell-to-cell communication in plants is mediated by chemical reactions that respond to a stimulus. One experiment found that carnivorous plants rapidly move to catch insects that stimulate trigger hairs, setting off a series of changes in expansion of cells that ultimately results in a meal.
While M. Night Shyamalan’s film may have intended to frighten his audience, it raises some important questions about the nature of communication, whose answers point to the reality that plants can communicate much like we can. Plant communication is both “accidental”, because it is sent without intent but interpreted accurately, and transactional, involving the construction of shared meaning between individuals. It can be described as the transfer of cues from one individual to another without any assumptions about the intent or benefit for the emitter or receiver. One significant question remains: If it is similar in many ways to human communication, how should we then respond?
Perhaps we should be listening more carefully. Contrary to M. Night Shyamalan’s portrayal of plant communication as hostile, we should recognize it as inherently “good”. The chemical cries of cut and wounded plants in the midst of a developing society plead with the human race to exercise stewardship in the midst of a selfish world.