Dr. Ted Stankowich

So trees versus ground, you might not want to be as armored.

There are spiny animals that live in trees.

It's just a matter of what you had to begin with.

Most of the ones that have a big defense tend to be a little bit slower, a little bit more lumbering because they don't need to be fast to get away.

That's not their main defense.

I noticed early on that.

especially working with skunks, that skunks aren't the smartest animals in the world.

I knew that armadillos aren't really the smartest animals in the world.

So we had a question of, well, maybe having to carry around this big coat of armor or evolve this stinky smell takes extra energy, and there might be a trade-off there.

So I thought, well, maybe they have smaller brains.

And so we did a study, and we found, lo and behold, that mammals that have more elaborate defenses, morphological defenses—

have relatively smaller brain sizes.

So you could say that those that have really strong defenses don't need to be as smart because they can hang out and not have a care in the world and know they're defended against most other mammals they find.

And also there's this energetic trade-off there, that there's a cost to growing, developing, and carrying around a giant coat of armor on your back all day long.

Yeah.

So the more you invest in your defense, the dumber relatively you tend to be.

Yeah, it's amazing because we took a whole different route, right?

Our evolutionary history, we became a little bit more custodial, a little bit more able to run and outpace.

And that's mainly in order to hunt.

But we would use trees, escape into trees.