Do brains trump brawn? A remarkable new study of how the human body prioritizes its inner workings found that if you intensely think at the same time as you intensely exercise, your performance in both thinking and moving can worsen. But your muscles’ performance will decline much more than your brain’s will, the study found.

The results raise interesting questions about the roles that our body’s wide-ranging abilities may have played in the evolution of humans and also whether a hard workout is the ideal time to be cogitating.

Compared to almost all other animals, we humans have disproportionately large brains for our size. Our supersized cranial contents probably provided an advantage during our evolution as a species. Smart creatures presumably could have outwitted predators and outmaneuvered prey, keeping themselves fed, uneaten and winners in the biological sweepstakes to pass on their genes.

But most other species eschewed developing similarly outsized brains during evolution, because large brains carry a hefty metabolic cost. Brains are extraordinarily hungry organs, requiring, ounce for ounce, more calories to sustain their operations than almost any other tissue, and these caloric demands rise when the brain is hard at work. Thinking demands considerable bodily fuel.