Plants can do arithmetic.
No, it’s not that they are doing quadratic equations or some such. Scientists from the John Innes Center in Norwich in the U.K. have found that plants do perform what could best be called arithmetic division overnight. The reason is to help them make it through the night without starving.
During the day, plants feed themselves by taking energy from the sun and converting carbon dioxide into sugars and starches. But at night, they have to rely on the starch they’ve stored up to survive till dawn returns.
From studying Arabidopsis (which is from the same family as cabbages and is commonly used in scientific studies), Professor Martin Howard found that plants ration out their stores of starch by making adjustments to how much they consume. As darkness could fall early or the sun appear (and disappear) at different times, such adjustments are necessary.
Via mathematical modeling, Howard found that plants go about this process very precisely by performing what would have to be called division. Science Daily explains:
During the night, mechanisms inside the leaf measure the size of the starch store and estimate the length of time until dawn. Information about time comes from an internal clock, similar to our own body clock. The size of the starch store is then divided by the length of time until dawn to set the correct rate of starch consumption, so that, by dawn, around 95 percent of starch is used up.
That is, even in the night, plants are still growing and producing. ”Understanding how plants continue to grow in the dark could help unlock new ways to boost crop yield,” comments metabolic biologist Professor Alison Smith.
What’s notable is how efficiently plants divy up their starch stores. Impulsively consuming all the starch at once could actually be disastrous, as Smith points out: “If the starch store is used too fast, plants will starve and stop growing during the night. If the store is used too slowly, some of it will be wasted.”
Arithmetic division is pretty basic math, of course, but it is still “astonishing” to know that plants can do such “in a simple, chemical way,” Smith says in the BBC. Howard underscores that their study (which is published in the online journal e-Life) “is the first concrete example in biology of such a sophisticated arithmetic calculation.”
Animals, including birds, may also drawn on similar chemically-based, arithmetic operations to ration out their store of fat while migrating or when they are unable to eat while incubating eggs.
Dr Richard Buggs of Queen Mary, University of London, emphasizes that the study is not evidence for plant intelligence, but simply “suggests that plants have a mechanism designed to automatically regulate how fast they burn carbohydrates at night.”
Howard’s and Smith’s research offers a window into the secret life of plants; to questions of plant sentience and (as one conference on this topic puts it), “the capacity of collaboration of plants with us animals.” Plants may not do math (as Buggs puts it) “with a purpose in mind like we do.” But any mother who opens the refrigerator (just stocked that afternoon with groceries) containing only a tomato and a jar of peanut butter has to admire plants’ ability to mete out their starch stores — their food — with such careful efficiency.
Photo via Ada Be/Flickr