Why are tropical animals so colorful? Archaeologists discover that parties 11,000 years ago were BYOB — bring your own boar But barns weren't originally red in fact, they weren't painted at all.

So they needed a cheap way to protect the barns' wood. They mixed skimmed milk, lime, and red iron oxide to make a red, plastic-like coating.

But we have a lot of wood, so they just painted it to look like brick,” explains Anna Blomster, a PhD in Scandinavian studies from UCLA who wrote her thesis on Swedish red cottages.

Ancient Romans used blood red, bright yellow and stunning white paints to illustrate dire warnings on the wall that separated them from the rebellious tribespeople of Scotland, a new study shows.

Iron. The stuff that makes red paint. And that, Zunger explains, is how the death of a star determines what color barns are painted.