What is Evolution?

Fossils provide evidence of how much (or how little) different organisms have changed since life developed on Earth.
The theory of evolution states that all species of living things have evolved from simple life-forms which first developed more than three billion years ago.
Studying the similarities and differences between species helps us to understand evolutionary and ecological relationships.

Fossils

Fossils are the remains of plants or animals that lived millions of years ago. The animal or plant may have been buried, e.g. by a mudslide, then its remains become part of the sedimentary rock that forms. We know that there has been life on Earth for about 3.5 billion years (The The Earth is about 4.5 billion years old) though for the first few billion these were very simple life forms e.g. bacteria. The first complex multi celled life forms appeared about 600 million years ago.

From studying fossils we can see that many life forms existed millions of years ago that do not exist now. There are no dinosaurs left. We can also see that there were life forms that are very similar to life forms which do exist now.

The theory of evolution states that over many generations life forms may change. New species come into being and other species become extinct. All species on Earth now evolved from very simple life forms that lived in the sea many millions of years ago, even humans.

The process of evolution happens very slowly. From generation to generation there are usually only very small changes. There is a lot of evidence for evolution; Fossils We can trace the development of species over time. It is clear that humans evolved from small furry mammals that survived ice ages that many reptiles didn't. These mammals evolved into apes and then humans evolved from these. DNA Just looking at apes we see huge similarities between them and us. Human and chimpanzee is very similar. At least 95% is exactly the same. Ecological Relationships If we study the similarities and differences between species alive now we can better understand how they evolved. Darwin was realised that the beaks of finches living on certain islands were different so that they could specialize in a certain food source. They all, however, evolved from a common ancestor.