Birds are smart. They use tools, engage in social learning, plan for the future, and do a variety of other things that were once thought to be exclusively the stuff of primates. But hundreds of millions of years of evolution separate mammals and birds, and structurally, their brains look very distinct. Plus there’s the whole size thing. If you look at a bird’s head, it’s clear that there’s not a whole lot of space for mental hardware in it. So how do the birds manage with smaller brains?

While other studies have tackled a lot of the structural differences, a new one released this week in PNAS shows that, to some extent, size doesn’t matter. Its authors show that birds pack neurons into their brains at densities well above those in mammals’ brains, putting some relatively compact bird brains into the same realm as those of primates when it comes to total cell counts.

And the funny thing is, we probably should have known this was the case.