Evolution is the theory of new species (different types of living things) arising over time. All animal and plants have evolved from one single organism many, many years ago.
In 1859 an important book was published. It was called ‘On the origin of the species.’ This was the first book that described the idea of evolution. It was written by a man from England called Charles Darwin. Darwin was a ‘naturalist’. A naturalist is someone who studies plants, animals and the natural environment. During a 5 year boat trip around the world, Darwin collected lots of different animals and plants to study. Some of these ‘specimens’ are in museums today! He saw lots of animals he had never seen before in England. He saw giant tortoises and very small birds!
There is a famous saying that is ‘survival of the fittest.’ This means that the animals that are best suited to where they live, are most likely to survive. If the animal survives, it is more likely to have children. Children are called ‘offspring’ in the animal world. For example a fish would not survive on land, it would dry up and not be able to breathe! This is because it has ‘adaptations’ to suit the water. They have gills that allow them to breathe underwater and fins for fast swimming. The fish would die and not have offspring. However, an elephant has adaptations to living on land. For example, it has 4 strong legs and a thick skin for protection against the sun and flies. This means the elephant will be able to survive and reproduce to have offspring. The environment influences which adaptations an animal has.
NATURAL SELECTION IN EVOLUTION
There are lots of different species in the world. A species is a group of animals that have similar characteristics. They are the same species if they can reproduce and have fertile offspring. Fertile means the ability to reproduce. For example, leopards are a species.
Within a species, the individuals are all a bit different. We know this as we can see some leopards with square shaped spots, some with circle spots and some with very few spots. These differences are called variation. The difference that is best suited to their environment will be passed down to their offspring. A very spotty leopard is more likely to survive in the forest than a less spotted leopard. This is because it can hide in the trees better- a more plain leopard would stand out! Therefore these spotted leopards will reproduce and produce more spotted offspring. Over many years, there will be many more spotted leopards than more plain leopards found in that place.