Who Chose the Critters' Color?

A playable post on the relationship between life and its environment.

This is a story about critters.

Critters are cute, colorful, and friendly! They have short lives compared to you and me, which they spend wandering around. Here's a critter that's color.

A critter gets its color from its parents.

After two critters bump together, one of them will give birth to a baby critter. This color critter and this color critter will have a color child.

Sometimes baby critters have a surprising color.

These critters are both color, but their child might not be. What color is it?

In the wild, a predator hunts critters.

Critters are cute, but they are also tasty. This beastie brings home critters to feed herself and her children.

Help the hungry beastie gather 150 critters!

In this ??? environment, the critters are ???. At night when they are sleeping, the beastie comes out to hunt. Her children are hungry, and she needs to find 150 critters as fast as possible.

When it gets dark, the beastie will come out. Once you see her, find critters for her by clicking on them with your mouse until the night is over. Then wait until the next night to keep going!

There's more to this story, but you have to finish hunting first.

The critters aren't the same color anymore.

The critters changed color! ??? days ago they were ???, but now they're ???.

On day
Most critters were

The critters' new color matches the environment.

The critters didn't change to any old color. These ??? critters are almost the same color as the ??? environment they live in. Did you notice that they got harder to find every day?

Day 1

Day ???

How did the critters change color?

Over the ??? days that you helped the beastie hunt, three things were happening.

Mutation

Some of the ??? critters' children were surprisingly ??? or ???.

Elimination

The ??? environment made ??? critters hard to see, so you found mostly ??? and ??? critters for the beastie.

Inheritance

The ??? critters that you didn't find passed that ??? color to their children.

This is called natural selection. It's a process that causes slow changes to living things.

Natural selection will do this every time.

No matter what color the environment is, or what color the critters start out with, they will become the same color as the environment through natural selection. See for yourself by starting again with different colors.

So, who chose the critters' color? Nobody.

It might seem strange, but it turns out that nobody chose the critters' color. Because of natural selection, their color changed on its own.

Thank you for reading this post!

I'm Rupert Deese. I wrote this post while working with Dan Amelang at CDG Labs in 2015.

Thanks to Nicky Case, Chaim Gingold, and all the other beta testers who helped make this what it is.

The "playable" format was inspired by Bret Victor's Explorable Explanations, and the excellent playable post Parable of the Polygons.