This tiny weed performs real arithmetic in the dark. Here’s how it uses its calculations not only to survive, but to time perfectly orchestrated chemical strikes.
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When we picture mathematics, we typically imagine calculators, computers, formulae and abacuses. What almost no one on Earth imagines is a plant, performing division in the dark. And yet that is precisely what one unassuming species of weed has evolved to do. Arabidopsis thaliana, or the thale cress is a tiny flowering plant that’s famous among biologists, as it has all but rewritten our understanding of what living organisms are capable of.
Here’s how this plant uses its nightly arithmetic in order to perfectly time a chemical ambush.
How This Plant Does Division
At first glance, the thale cress is nothing special. It’s just a rosette of modest green leaves, which you could easily step over without a second thought. But once the sun dips below the horizon, an elegant biochemical computation begins inside its cells.
Arabidopsis thaliana, thale cress, mouse-ear cress or arabidopsis (photo by: bildagentur-online/uig via getty images)
Universal Images Group via Getty Images
As 2013 research from eLife explains, during the day, Arabidopsis gathers sunlight and converts it into starch, which serves as its energy reserve. But as soon as night falls, the thale cress depends entirely on that stored starch in order to survive.
As such, instead of burning it at a constant rate, a random rate or all at once, Arabidopsis performs a simple yet sophisticated calculation: it divides the total amount of starch it has stored by the number of hours left until dawn. In simpler terms: stored starch ÷ hours until expected dawn = nightly consumption rate.
When necessary, it even accounts for exceptions. If the night comes early, for instance, the thale cress recalculates and slows its consumption so it doesn’t run out.
Why This Plant’s Counting Skills Matter
If the thale cress stored all its starch only to misuse it (i.e. burning it either too quickly or too slowly), it could face several problems that threaten its odds of survival:
If Arabidopsis burns its reserves too fast, it risks starvation before dawnIf it burns too slowly, leftover starch is wasted, which is a missed opportunity for growthMismanagement in general is likely to leave the cress vulnerable to either stress or damage
But by leveraging its ability to do real-time arithmetic, the thale cress ensures that its energy lasts exactly as long as it needs to. This kind of precision is vital for efficient growth and long-term health.
How The Thale Cress Plant Times Its Chemical Attack
Most fascinatingly, Arabidopsis’s talent for arithmetic isn’t just a means for conserving its energy. It’s also central to its defense strategy.
Specifically, starch consumption isn’t the only biological process that it precalculates; it also preemptively ramps up the production of glucosinolates. In simple terms, these are potent chemical compounds that plants often use as a defense mechanism against predators (mostly insects). These chemicals function like a “mustard-oil bomb”: when the plant is attacked by pests or pathogens, the glucosinolates activate and become toxic.
As a 2019 study from Plant Physiology explains, Arabidopsis times the production of these defensive chemicals with mathematical precision. During the small hours of the night, as herbivores begin to stir or dawn approaches, the thale cress’s glucosinolate levels rise. Notably, it doesn’t produce these chemicals at a random rate; it’s synchronized to its internal clock and its starch budget. In turn, it optimizes its defense machinery for the highest possible protection at the moment of greatest threat.
How Does A Brainless Plant Do Math?
Arabidopsis pulls this off its nightly mathematics with a biochemical network, rather than neurons or a brain. Key elements of this network includes:
A circadian clock. Arabidopsis has an internal molecular timekeeper that tracks the approach of sunrise and sunset, just like we humans do. In essence, every single one of its cells “knows” the time of night.Starch sensors. It has chemical signals that are able to detect exactly how much starch remains in its energy reserves.Specialized enzymes. The thale cress uses an enzyme called PWD to modify starch granules and regulate their breakdown.
The discovery of Arabidopsis’s arithmetic skills has had far-reaching implications. For one, understanding how plants manage their energy at night could prove invaluable to breeders who engineer crops for better survival in unpredictable light conditions or under stress. Similarly, the same principles could be repurposed in engineered microbes or cells in order to build biological timers or systems that “compute” with molecules.
But most importantly, it also implies that, if plants can perform predictive calculations, the concept of intelligence likely isn’t only reserved for organisms with brains. Instead, it’s likely possible for anything that has the ability to process information and respond adaptively.
This overhauls many of the long-held assumptions humans have biasedly put forward about what counts as “thinking.” Life, in its broad and inventive forms, often thinks in ways we haven’t learned to notice, let alone even considered. Arabidopsis has simply given us the most surprising example yet: a plant that counts, calculates, defends itself and, ultimately, survives with a single, rudimentary equation.
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