Guppies Reveal the Evolutionary Cost of Big Brains
There’s a lot to be said for smarts—at least we humans, with some of the biggest brains in relation to our bodies in the animal kingdom, certainly seem to think so. The size of animal brains is extravagantly well-studied, as scientists have long sought to understand why our ancestors developed such complex and energetically costly neural circuitry.
A unique study recently published in Current Biology has taken a new approach to examining this age old question. Rather than comparing species with bigger brain-to-body ratios to smaller-brained relatives, they exploited the natural variation of brain size in guppies, which, as it turns out, aren’t as dumb as they look. They’re able to learn, and show rudimentary ability to count. Researchers from Uppsala University in Sweden were able to use their numerical abilities to test whether brain size affects intelligence in these simple fish.