Yes, plants can communicate with each other. Here's why some scientists say they're smarter than you think

The Sunday Magazine19:36Yes, plants can communicate with each other. Here's why some scientists say they're smarter than you think

Plants are an essential part of life. We rely on them for food, oxygen, water and more. Yet, many of us still don't know much about them. 

While plants may lack a brain, some researchers say these living things are smarter and more similar to us than we think. 

Plants can interpret sound, respond to touch and recognize their own kin. They can even communicate with one another about impending threats, summoning the help of predatory killers when they are being attacked. 

Zoë Schlanger, a science and environment writer at The Atlantic, explores this topic in her new book The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth. 

She spoke with The Sunday Magazine guest host David Common about her surprising discoveries and why not all researchers agree on plant intelligence. 

Can you break down why there are different views in the debate? I mean, is it a controversial thing to say, "Are plants intelligent?" 

It is, and probably the most central reason it's controversial is because plants don't have brains. I mean, the idea of animal intelligence is new enough that extending that realm to a brainless organism is a pretty far-fetched concept. 

But the reason there was a debate is because of improving technology and a waning away of old biases against doing this kind of research. Scientists were finding incredible things that plants could do, finding that they were very active creatures with the ability to make decisions and behave spontaneously and communicate and have these social lives. 

Let's jump right into some of the groundbreaking research that you got to see firsthand, including at a lab in Wisconsin and this plant that had a tangible response to being pinched. 

This was a shocking moment for me. I went to the lab of Simon Gilroy, who's a professor at [the  University of Wisconsin–Madison]. He is using plants that have been imbued with this fluorescent protein from glow-in-the-dark jellyfish, and he's using it to track a signal moving through the plant. 

He went into this dark microscope room, and one of his researchers handed me a pair of tweezers and told me to pinch the leaf of a plant that was under the microscope. And at first, I pinched it kind of gingerly because it felt sort of cruel to do. And they're like, "No, no, you have to pinch much harder." 

I pinched hard enough to break the midrib of a leaf. And then I saw, on the screen that was reading out from the microscope, this green light emanating from the place where I pinched it, slowly moving throughout the entire plant. Within about two minutes, the green had moved through the whole plant in this vein-like pattern that is very reminiscent of our own nervous system pattern.

Like sensing pain, it reverberates through your body. 

Exactly. Now of course, plants don't have brains, so presumably [they] have no pain receptors. But this plant absolutely knew I was pinching it. 

This felt so intimately shocking to me, because I had been researching plant intelligence for a couple of years at that point, and most of what we learn is invisible to us. You can't see the chemicals plants use to communicate that are drifting in the air. You can't see the plant's roots making a choice to grow in a new direction. It put everything together for me in this tangible way. Here was a creature that knew I was touching it.

You also explore the idea of how plants communicate. 

Plants have this ability that we simply don't, which is to synthesize complex chemical compounds in their bodies and then release them through these pores on their leaves. And under a microscope, if you want a picture, the pores look like little fish lips that open and close. It's actually very funny. Plants are making these compounds all the time. 

Some of them come with a lot of information that other plants use. So if a caterpillar is attacking a plant and the plant is sensing it's being eaten, it can also sample the saliva of the caterpillar that's chewing it and produce pesticides specific to that creature that's eating it. But it will also produce these compounds that float out of its pores and alert its kin — its fellow plants — that there's an attack coming.

Those plants can boost their immune systems. They can start pumping their own leaves full of something that would make them taste bitter or something that would repel their pests. Or in some cases, they do this incredible thing where they receive the signal of an attack, then they produce new compounds that lure in the exact predator of whatever's eating it. 

These are really complicated, multi-layered, multi-species conversations that are happening all the time and we have no idea. 

What have you learned about the way in which the research you've done, the conversations you've had around plant intelligence, and how they might relate to climate change? 

I really feel more connected to the material reality of climate change and also to this sense of enchantment that there's so much in this world to keep going as stewards of it, and how we feel about plants is really going to determine their future at this point. 

I mean, they literally made the habitable world that we live in. Our ability to breathe oxygen and every molecule of sugar that you've ever ingested that makes every single organ in your body work — that was all produced by plants. And yet, their fate rests wholly in our hands now. That's a reality I feel much more connected with now.

Q&A edited for clarity and length. Interview produced by Andrea Hoang.