If a plant neurobiologist fell in the lab and no one was around to hear her, would the trees know it? It’s questions like this that likely keep plant neurobiologists up at night, especially since no one else seems to be listening to them. This could be because so few people believe in such a thing as plant neurobiologists. Or else they believe they are just as lacking as their study subjects, which lack the brain and central nervous systems that more respectable neurobiologists study. Plant neurobiologists respond by saying that maybe it’s time they start believing, because it’s not any members of the Plant Kingdom who are turning up the heat on our greenhouse.
Charles Darwin was one of the early believers, when he wrote in 1880 that the root of a plant “acts like the brain of one of the lower animals.” He wasn’t referring to his detractors. What he was referring to is a plant’s complex responses to various external sensations like sound, touch, light, temperature, and vegetarians. It turns out that when you’re on the bottom of the food chain, it was pretty smart to evolve millions of individual roots instead of a single head with a single brain. It is this root network that allows plants to lose 90 percent of their biomass and still survive. If survival is any measure of intelligence, the Animal Kingdom has a long way to go, despite the impressive runs of the cockroach and “As the World Turns.” Plants were here long before animals, and, the scientists say, will likely be here long after the human animals have completely lost their heads.
But, you scoff, a plant can’t learn, much less remember what it learned. To which the plants respond, “Oh yeah? WE don’t write history books and then forget about them.” Or they would if they weren’t so sensitive. But actions speak louder than words, as when mimosa pudica, called the “sensitive plant” for its ability to fold up its leaves when threatened, demonstrated its learning abilities in a recent experiment. Fifty-six plants were subjected to a threat (dropping from a small height), whereupon they all closed their leaves. As the threat was repeated over the course of a day, the plants stopped responding, appearing to learn that the threat wasn’t real. Even when the experiment was repeated a month later, the plants kept their leaves open, suggesting a memory of the fake threat. Try that with your average human and see what happens, besides a lawsuit I mean.
Then there’s the classical conditioning experiment made famous by Pavlov which proved that pea plants are just as capable of learning as dogs. The plants were repeatedly subjected to a stimulus (a breeze from a fan), and at the same time given a food reward (light), to develop an association. Within four days, all the plants had learned to lean towards the fan even when the light was kept off. Dogs have also apparently learned something from this experiment and have taken to picking any peas out of their food.
Plants, of course, can’t compete with most humans on IQ tests, though there is no shortage of humans who appear to be competing with them. Those humans would likely fare poorly when going head to root with a Venus Fly Trap for instance, which seems to count the number of times hairs are triggered on their traps before they snap shut, thereby improving its odds of catching an insect instead of some falling debris. Many humans snap their mouths shut at anything resembling food, and plenty of things that don’t.
Many weeds, like quack grass, grow and spread with abandon, outsmarting farmers, gardeners, and fanatical lawn manicurists all the time, as well as a billion dollar weed killer industry designed to stop them. So far all their efforts appear to stop is the spread of a healthy environment and any possibility of a compromise. The weeds have apparently learned that one way to remove humans from their world is by getting them to poison themselves.
The oldest living organism on earth is believed to be a Bristlecone Pine tree in California, which, like most plants, lives largely on atmospheric gases, sunlight, water, soil nutrients, and a Green philosophy that makes the human version still look like the world on Miracle-Gro. It does not have a brain, yet has figured out how to live 4,900 years longer than the oldest humans, many of which have functioning brains but still have only figured out how to live on fast food, vitamin supplements, and delusions of superiority. The smartest plants of all, however, may be the crop plants. These smarty plants have figured out how to get humans to do the work of sowing their seeds for them, caring for them, and spreading them around the globe, all while getting them to believe that it was they who domesticated plants. Even a potato likely knows that plants domesticated humans.
Plants make up 99 percent of the world’s biomass, despite the teamwork between the fast food industry and American consumers. The rest belongs mostly to the animals and the fungi, and the fungi are already teaming up with plants via symbiotic underground mycorrhizal networks. It shouldn’t take a plant neurobiologist to understand that it’s time we listen to them, before they decide to leave us no breathing room at all.