The up-goer five text editor - second piece of writing

Here is another piece of writing I did using the up-goer five text editor. Like in the other piece of writing I did using that website, I could only use the one-thousand most common words. Can you guess what I wrote about?

A long, long time ago there were some animals that were good at what they did, and had big brains and got a lot out of it. There were also some animals that were not so good at what they did. They did not know a lot of things and were not as fast or strong. Because of that, it was easy for other animals to eat them and they could get stuck in places without food easily. They all got eaten or died because they could not find food or run away fast enough.

The animals that did know a lot did not get eaten because they knew how to avoid trouble. They had babies who knew lots of things because their parents did. The stupid animals did not have babies, because they had died, so none of them lived on.

Some animals did not die because they were stupid. They died because they did not look right and the animals that they wanted to eat could see them. When those animals saw them they ran away because they didn't want to get eaten. Then the ones who wanted to eat them died of not having food. Only the ones that looked right could get food lived because the food did not see them. They had babies and those babies lived because they were like their parents. The few who weren't like their parents didn't live; they got eaten. Soon only the ones who looked right lived.

Some types of animal became bigger or smaller or lost or changed parts of their bodies because that was what was good for them. This happened over many, many years because it took time for all the non good, non useful ones to die.

Because of all this, animals changed and turned into different kinds of animals that were better in that part of the world. They only changed in parts of the world that they could not live in. They didn't change in other parts of the world because the food, other animals, leaves, ground and how much water there was, was different and good for them there.

A man told lots of people about this. First most of them didn't believe him. They thought all the animals were around at the same time. Soon more and more people believed him. Then lots of people knew about him and his idea.