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Smarty Plants: Intelligence and Learning in Garden Greenery [EXCLUSIVE]

Dec 19, 2014 01:43 PM EST
fly trap

(Photo : Flickr: rumpleteaser)

"Plant intelligence" is a term that's been thrown around a lot these days, especially by a number of scientists. But plants can't really think - or can they? Plants do indeed show signs of "intelligent" behavior, and even learn from interacting with what is around them.

Anthony Trewavas, a molecular plant scientist at the University of Edinburgh explains.

"Intelligence comes from the Latin word 'interlegere' - to choose between," Trewavas said in an exclusive interview with Nature World News. "[That's] not a bad definition because choice implies a number of things: something that has happened in the past that needs a decision, thought, or assessment process to go on to make a decision about a future form of behavior."

"In humans we call assessment 'thinking' and use a brain for it," he added  "Plants assess but they don't use nervous systems for that because they don't have one; so it's chemical [based] and operating in a different way."

Trewavas has been working toward understanding plant intelligence since 1984, when he came across a statement by Nobel Prize laureate and plant biologist Barbara McClintock.

"A goal for the future would be to determine the extent of knowledge that a cell has of itself and how it uses that knowledge in a thoughtful manner when challenged," Trewavas recited, going on to explain that "the response to challenge is behavior and thoughtful responses are intelligence."

Not even two years after reading that quote, the biologist found himself drawing up comparisons between human neural pathways - essential for communication between brain and body - and acid biosynthetic pathways in plants. (Scroll to read on...)

A stained overlay of human neural activity. We may know enough to understand that these little cellular structures are essential for thought. However, how exactly they help us form and retain memory remains a complete mystery.
(Photo : Flickr: Mark Miller) A stained overlay of human neural activity. We may know enough to understand that these little cellular structures are essential for thought. However, how exactly they help us form and retain memory remains a mystery.

Trewavas suspected that these plant pathways, used for the metabolic processes that let plants use energy and make chemical changes, may function similarly to how neurons help facilitate interactions between different parts of the brain, creating what we call "thought" or even memory.

"However, mentioning what I thought at the time to other colleagues invariably produced a ferociously negative response, so jottings were put away in a drawer until I had time to marshal all the arguments," he said.

This didn't come as a huge surprise. After all, it's hard to wrap your head around the idea that a tree or vine might be "thinking" in its own sense of the word. However, as of late, the expert says he's noticed a notable shift toward acceptance of these ideas.

That may, in part, have a lot to do with evidence of plant adaptations that seem far too clever, and change far too readily to be the results of simple natural selection.

"Climbing plants for example - if you provide a glass rod for them to climb around - start the whole business of winding around it. Then, because glass is too slippery, they unwind and go and look elsewhere for a rougher surface to grip," Trewavas said. "That's an obvious assessment of surface."

Carnivorous plants provide another great example. In the case of the well-known Venus flytrap, it snaps closed after the sensitive hairs inside its "jaws" are touched. When insect prey triggers these hairs, the jaws will stay closed for days to slowly digest the meal. However, if a researcher were to trigger the same reaction with a stick, the trap quickly reopens, as if it knows there is no prey to digest. (Scroll to read on...)

fky trap
(Photo : Flickr: Axel Bührmann)

Trewavas adds that a most stunning example of plants assessing their environments may have actually first been observed by Charles Darwin.

"[The Bignonia] plant seeks to adhere towards an appropriate surface and it does so using a tendril that is inserted into crevice or hole," Trewavas said.

According to the researcher, Darwin observed the plant acting like a human cliff climber, searching for the perfect "handhold" before making its next action. If a hole proved too small or lose, it would withdraw its tendril and select another, until the perfect fit was found.

These kinds of observations, Trewavas admits, won't be found in textbooks. Instead, they can be found in a surprising amount of scientific literature. He suggests that this may be because humans are used to understanding intelligence in terms of what we're familiar with.

"The crow family is commonly described as intelligent but they express it using beak and claw," he said. (Scroll to read on...)

(Photo : pixabay)

When a crow uses these things for complex behavior, we compare it to us using our hands. Tool use, for instance, is a common way experts identify high levels of intelligence in animals. However, plants don't have hands, claws, or beaks, and aside from rare instances like with the Bignonia, it's hard to draw parallels between behaviors.

"You have to judge intelligent behavior in terms of what [plants] can actually do, and that is changing growth or [appearance]." Trewavas explained. "They will do this actively in response to their perception of the environment in which they live. But changing growth patterns is very slow and thus we end up not perceiving any kind of behavior at all."

Instead, he says, you have to look to the chemical shifts and molecular change inside a plant - behavior that's invisible to the naked eye, but likely just as important to these stationary organisms as hands are to humans. Understanding this simple fact will eventually allow us to determine just how smart plants really are on a scale all their own.

If you are interested in learning more about plant intelligence, Trewavas, and his work, be sure to check out the expert's latest book Plant Behaviour and Intelligence, which was released for download and in a hardcover edition earlier this year.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

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