Why Are Brains Wrinkly? Are There Smooth Brains?

(Last Updated On: December 2, 2019)

Why Are Brains Wrinkly?

We’ve all heard the grey matter mass hiding in our skulls called our “noodle” before. That’s probably because the brain, on the outside, looks kind of like a noodle wrapped and laid over itself, since its all wrinkly like that. But, why exactly are brains wrinkly? Is a wrinkly brain better than having a smooth brain? We’ll get to all of that.

Wrinkly Brains

So, the brain isn’t actually a noodle laid over itself like your intestines. If you take a cross section of your brain, it’s actually more like a raisin. The inside is still all solid, the wrinkles more like folds or a valley sitting in the brain. They’re called sulci and gyri, stemming from the Latin for “ridge” and “ring” respectively. 

But Why the Wrinkles?

Generally speaking, a lot of things exist because they helped us survive. We have eyes on the front of our heads because it allowed us to track prey better within a focused view. Animals like cows and rabbits have eyes on the sides of their heads for the exact opposite reason, they get a field of view close to something like 360 degrees. That way they can avoid predators like us.

The point here was to illustrate something we come back to on the blog quite a bit–natural selection. At some point long ago, wrinkly brains made our ancestors more successful than the other evolutionary competitors. 

You can actually demonstrate why the wrinkles are better by taking a sheet of paper. It’s all about surface area. If you take two sheets of paper, laying them flat on a table, they both have the same surface area. Because you know, they’re the same. 

Now crumple one into a ball. It takes up a lot less space than the sheet, partly because it’s all wrinkled. It’s the same thing with your brain, because your brain cells are also on the brain’s surface (what a concept).

Keeping a wrinkly brain allows it to have more surface area while taking up the same volume. More surface area means more brain cells, which basically makes you smarter.*

*In theory–sometimes people can be dumb.

Are Smooth Brains Bad?

Yes. Dear god yes smooth brains are bad.

You’ve probably heard of our cuddly friends; the koala. While they’re critically endangered thanks to recent climate change events, koalas are also incredibly dumb. 

Like even the food they eat is terrible for them. That’s why koalas are almost always sleeping. Eucalyptus leaves (basically their sole diet) are poisonous for most other animals–luckily the koalas are an exception. Unluckily, eucalyptus is not nutritious at all, and also is really hard to digest. Plus, while koalas are relatively resistant to eucalyptus poison, they’re far from immune. So it’s possible for koalas to poison themselves with their own diet if they go too far.

As for being hard to digest, so much energy is devoted to breaking down the leaves, so koalas have to sleep to make it all up.

It gets worse, because koalas are so dumb they only recognize eucalyptus leaves on a branch. If you plucked some leaves and put them on a plate for a koala, it wouldn’t recognize the food as food. Which means you could theoretically starve a koala to death in a room full of the only thing it eats.

Koala teeth also aren’t made to eat eucalyptus. Some herbivores get around grinding their teeth by having them grow nonstop, or what have you. Koalas don’t have that, so once their teeth grind down (often before they die of old age), they just… Give up and starve to death. That’s got nothing to do with smooth brains we just thought it was incredibly pathetic from an evolutionary standpoint.

These bears also fall out of trees a lot (this is because they’re dumb) so sometimes they’ll just die falling out of a tree. 

Basically, koalas have really smooth brains and that’s why they’re so stupid. 

Koalas and Climate Change

Stupid as koalas are, it would be a shame to lose them to rampant climate change (no seriously Australia is on fire). If you’d like to donate to our friendly bear-fiends, here’s a link.

Think you know your brain anatomy? Test your neurological knowledge here.



About Kyler 707 Articles
Kyler is a content writer at Sporcle living in Seattle, and is currently studying at the University of Washington School of Law. He's been writing for Sporcle since 2019; sometimes the blog is an excellent platform to answer random personal questions he has about the world. Most of his free time is spent drinking black coffee like water.