Think of a rain forest — rich with trees, covered by clouds, wet all the time.

Then ask yourself, how did this rain forest get started?

I ask, because the answer is so going to surprise you. It's not what you think.

Until I saw the video you're about to see, I just figured that a rain forest starts when a place gets rainier. (Why it gets rainier, I don't know. I don't think about that.) And then — once it starts raining all the time — tropical, rain-loving trees start to grow. They grow everywhere, and make a forest.

So I figure that's the order: rain first, forest second. It's like the name. We don't call these places forest-rains; our name for them describes how they came to be.

Or so I thought.

Now watch this — from the folks at MinuteEarth, with science explainer (and animator) Henry Reich narrating:

This isn't my first "Which came first?" story. I have also tackled the granddaddy of the genre — chicken vs. egg — and I went with the chicken. Here's why.

Copyright 2021 NPR. To see more, visit https://www.npr.org.