The human brain has 100 billion brain cells. The worm C. elegans has 302.

But the worm’s tiny brain can solve calculus problems, researchers say. Finding food motivates the millimeter-long nematode to do college math. Its food-hunting strategy works something like the hotter-colder game, says University of Oregon biologist Shawn Lockery. When a worm senses tastes getting weaker, it turns to another direction. When it senses tastes getting stronger, it wriggles forward.

To do this, the worms must calculate the rate that a flavor changes over time. They pull it off using one brain cell on the left to compute increasing concentrations and one on the right to compute decreasing ones, Lockery’s team reported in Thursday’s edition of the journal Nature.

The scientists rigged the cells to light up when active and then exposed the worms to increasing or decreasing concentrations of salt.

They also equipped the sensory cells with a custom switch triggered by the spicy chemical in chile peppers. When they applied it to worms with customized left-side neurons, the worms moved straight ahead as if sensing an increasing concentration of food. When they applied the chemical to worms with right-customized neurons, the worms randomly turned as if sensing weakening concentrations.

No need to feel humbled by mathematical nematodes. Lockery says human brains have circuits that solve similar calculus all the time, subconsciously telling us things such as whether the tantalizing aroma from a pizzeria is getting stronger.

Understanding the physical basis of human thought is the long-term goal of Lockery, another UO researcher and colleagues in San Diego, Toronto and Cambridge, England.

While worms might seem an odd subject, Lockery says, “they have intelligent, goal-directed behavior, and it tends to be easier to measure and quantify.”