Mutations and evolution
All living creatures have genes, made up of DNA. Without DNA mutations, life on Earth could not have evolved. Mutations can affect the way a gene works, which may in turn cause changes in an animal's appearance, or behaviour. Sometimes, a new gene variant may mean the animal is better adapted to its surroundings, improving its chances of survival. So this animal is more likely to have offspring, which will inherit the beneficial gene variant. This process is called natural selection.