What is Evolution?

Evolution is the process by which new types of animals and plants arise from older types. Fossils provide some of the best evidence that this happens: by looking at fossils in order of how old they are, we can see how the ancestors of modern creatures gradually changed into their familiar forms today. This is also true of human beings - a family tree of different kinds of human beings and their ancestors, stretching back millions of years, is gradually being discovered.

How does Evolution Work?

The information that tells a body how to develop is stored in its DNA, a complicated type of molecule that exists in the nucleus of every cell of your body. This DNA is passed down the generations because it copies itself. Every now and then it does not copy accurately and the resultant organism is slightly different as a result. This is called a mutation.

If this difference causes the organism to be more likely to survive, then those changes in the DNA are more likely to be passed on. If the difference causes the organism to be less likely to survive, then the changes are less likely to be passed on because the organism is more likely to die before it can breed.

In this way, beneficial mutations spread through a population. Over time, this causes whole species to change, or whole new species to branch off from them. A species is considered separate from its parent species when it can no longer breed with them. Over nearly four billion years, this basic mechanism (called natural selection) has produced all the diversity of creatures on the earth today, probably from one single ancestor.

Natural selection and was discovered by Victorian scientists Charles Darwin and Alfred Russell Wallace.