Brain size isn’t everything

The ants’ brains are tiny, but they work together to build relatively large houses and coordinate their foraging. (Glenn Orzepowski /)

When we think, each of our brain cells sends signals to up to 1,000 neighboring neurons up to 200 times per second. This allows for complex decision making, such as navigating a four-way stop or solving an algebra problem. But animals with small heads (or none at all) also perform complex tasks – no brain fireworks are needed.

Ants’ brains are hundreds of thousands of times smaller than ours, rendering them incapable of significant individual computing power. Instead, they use a complex beehive-like mental communication system, says Simon Garnier, an entomologist at the New Jersey Institute of Technology. Insects emit chemicals called pheromones when they find a resource, such as food or a nesting site. Hundreds of fellow ants follow the scent, leading to an organized army of sated creatures or the construction of a giant anthill (relatively speaking).

Even brainless, single-celled organisms called slime molds can understand simple lessons, says Audrey Dussutour, a biologist at the University of Toulouse. She learned at these places to cut through salty soil stains by gradually filling them with sodium. The more salt they contained, the faster they “realized” that they could cross safely, showing that an elaborate neural network is not the only key to success.

This story appears in the Winter 2020, transformation problem of Popular science.