Meat eaters rejoice! You can finally tell your vegetarian friends to get off their high horses. While their kale may be laying utterly motionless on their plate, the leafy green knows all too well — and perhaps even dreads — that it will soon be eaten.
The news: University of Missouri researchers Heidi Appel and Rex Cocroft have demonstrated that plants are able to sense themselves being ingested. They can even respond to their impending demise by triggering defenses.
The science: To test their theory, the researchers placed greens-loving caterpillars on thale cress (known scientifically as Arabidopsis), which is similar to mustard, cabbage and kale. Then they placed lasers and a small mirror on the leafy greens to mimic the vibrations that ensue when caterpillars feed on them. When the scientists later put actual caterpillars on the plants, they found that previous exposure to the "feeding-like vibrations" resulted in increase levels of mustards oils — a chemical that repels many species of herbivorous insects — than would have been found on non-lasered plants.
In other words, the plants actively responded to what they perceived as an imminent threat by activating their defenses. While it's long been known that plants can be surprisingly responsive to outside stimuli, this is the first experiment that demonstrates they can respond to what Appel describes as an "ecologically relevant vibration."
Other research has greatly expanded scientific understanding of the ways in which plants can respond to external stimuli in unexpected ways. The video below from the Smithsonian Channel, for example, shows how plants can use electrical impulses to things like fire.
Why you should care: Science is steadily revealing plants to be more in tune with their surroundings than was previously believed.
That's not to say that plants can, say, suffer in the same way that animals can, since they lack a central nervous system. But the belief that animals are sentient beings with self-awareness, while plants are just "there" might have to be thrown out the window.
So the next time you much on some fresh salad, remember that your kale very much does not want to be digested.