Crows show how to count without a neocortex

To see, you (usually) need eyes. To walk, legs are important. To invent and handle abstract thought, like math, it’s believed you really should have a neocortex. Nature doesn’t like to be that limiting though, and while the neocortex is a brain feature found in mammals, big-brained birds like crows have developed their own neurology that allow them to understand quantities well enough to do some counting.

Researchers in Germany gave crows tasks that depended on them recognizing the number of dots on a screen in order to get a reward. The dots were rearranged so that the birds couldn’t just memorize certain images, but would have had to match specific quantities. They’d need to count them. Crows have long thought to posses some awareness of quantities, but in a limited sense, possibly only up to three. This study didn’t blow that cap out of the water, but did hone in on what part of the birds’ brains is doing the counting.

No prefrontal cortex, no problem

Without a neocortex, it appears that the crows have been using their nidopallium caudolaterale, a region at the front of the birds’ brains tied to various higher functions, to handle counting. During tests, specific neurons in the nidopallium caudolaterale activated for each different quantity the bird observed. Color, shape and orientation observations were all discrete from this activity, indicating these brain cells served this very specific purpose. Despite being a different structure from primate counting neurons entirely, the actual functionality at play here is a close match for how we count. While we usually think of convergent evolution in terms of visible structures, it looks like evolution has pushed an unrelated brain structure to solve the number problem the same way in these two different lineages.

Other avian number-crunchers

This isn’t the first time birds seemed to be aware of quantities. Robins were tested for their sensitivity to shifting numbers of mealworms. Baby chicks can notice when quantities in inanimate objects change, even if the size and coloration doesn’t. The crows behavior, however, leaves fewer questions about other explanations, and shows specific brain activity tied to this specific task.

Source: How Do Crows Count? by Shaunacy Ferro, mental_floss