Can “behavior” exist absent a brain or nervous system?

Spring in the northern Temperate zone brings an effusive burst of life. Flowers and leaves appear on trees and shrubs from seemingly dead branches, while non-woody perennials emerge from the ground as if from hiding. The burst of flowers and the flush of leaves seems almost miraculous — one day it’s all brown, the next a riotous palette of color.

Pay closer attention, and you’ll see more. A few sunny days leads to a quick advance, as flowers open, leaves expand, and branches grow. A few cold days and progress halts, waiting, on the edge, anticipating the warmer days to come. The return of warmer days sets the process in motion once again. Rarely, though, do we stop and think about how plants do. How do they know the difference between a warm sunny day and a gloomy, overcast one? How do they know up from down, how do they find the sun? How do their roots forage underground?

Without a brain, a nervous system, or a circulatory system anything like ours, it’s hard for most people to imagine how plants respond to stimuli. Pre-programmed instructions, encoded in a plant’s DNA, can’t tell them how to respond to cold days or warm ones, or where to find the sun. They need to be able to collect information about their environment, and use that information to inform actions. There’s an ongoing debate in plant biology about whether these responses can best be understood simply in terms of physiological responses, or whether it’s reasonable to explore these in terms of behavior and consciousness.

An article published in the May 2021 issue of Trends in Plant Science (paywalled) by Elizabeth Van Volkenburgh, Kaaren Mirzaei and Yesenia Ybarra discusses their experience with the “Physiological Basis for Plant Behavior” class, a senior undergraduate biology class at the University of Washington. The class used the idea of plant behavior as a way to understand plant physiology, and created or expanded Wikipedia articles on topics like hydraulic signaling in plantsplant nucleus movementplant memoryelectrophoresis, and plant root exudates. Plant physiology as a whole is under-covered in Wikipedia, and few articles take a “behavior” approach, so the work that this class did not only fills important gaps in information, but also adds perspectives and interpretive frames that would otherwise be absent.

Since 2016, Dr. Van Volkenburgh has taught six courses with Wiki Education. In that time, her students have added more than 120,000 words to 200 different articles on Wikipedia. Over time, this amounts to a substantial corpus of work in an important area of knowledge. Not only has this impacted the information that’s available to the public, it also has shared this knowledge in a way that’s usually a lot more comprehensible than the average academic paper (assuming that it’s even accessible, and not hidden behind a paywall).

Image credit: Peter Valic, CC BY-SA 3.0, via Wikimedia Commons


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