Natural Selection on this Moment of Science.

You may know that by "natural selection", biologists mean the processes by which living things evolve. For example, a butterfly that happens to be colored like the trees it lives on will be less likely to be seen and eaten, and therefore more likely to pass on its genes to the next generation. Gradually the whole species becomes camouflaged.

In this instance, nature is said to have "selected" the camouflaged butterfly over other variations that weren't as well hidden. In "artificial selection," the same thing happens, only we human beings make the choices. Not many people realize how many of the living things around us are the way they are because of artificial selection!

For example, corn has been intentionally bred by humans to be more edible. Horses are bred to be strong and fast, sheep to have soft wool, turkeys to be big and fat, cows to produce plenty of milk. All it takes is successive generations of humans breeding the tomatoes they like or the roses they like or the grapes they like in order for new forms to exist that wouldn't otherwise have arisen.