All living things today evolved from simple life forms over 3 billion years ago. Charles Darwin published his theory of natural selection in 1858, proposing that organisms better suited to their environment are more likely to survive and reproduce, passing on their genes. Over time, natural selection leads to organisms changing as traits that increase chances of survival and reproduction become more common. While controversial initially, natural selection explains how species evolve in response to their environment over many generations without need for divine intervention.

1. Evolution All species of living things alive today (and many more extinct species) have evolved from simple life forms which first developed more than 3 billion years ago

2. Charles Darwin Published his theory of evolution by natural selection in 1858 It was not accepted at first Many people thought that God created life (and lots of people still believe this) Some people did not like to think that humans could have evolved from apes

3. Natural selection 1 Individuals within a species show a lot of variation Large numbers die due to predation, competition and disease

4. Some individuals have characteristics that make them more suited to their environment These individuals will survive And breed, Passing on their suitable genes Over time, the organisms change Natural selection 2 A suit

5. This is sometimes called…. Survival of the fittest

6. Question What is the difference between natural selection and artificial selection ? Artificial selection involves humans picking the best organisms to breed with. Natural selection is when the best suited organisms survive and breed. Natural selection is when humans pick the best organisms to breed with artificial selection is when the best suited organisms survive and breed. Click on your choices

7. Before the industrial revolution tree trunks were light coloured. dark moths could be seen and were eaten by birds. They were very scarce Peppered Moths 1 Light coloured moths could not be seen They survived and bred

8. Peppered Moths 2 After the industrial revolution tree trunks became covered in soot Light moths became easier to see but dark moths harder to see Dark moths survived and bred Light moths declined in numbers

9. Antibiotics These drugs are used to kill the bacteria that cause disease Sometimes mutations in bacteria stop the antibiotics from killing them What do you think will happen to these bacteria?

10. The Giraffe’s neck Over time, giraffes necks have got longer and longer Can you explain why? Draw a flow chart showing how this is thought to have happened.

11. Summary Individuals in a species __________ because of difference in their genes. They compete for food and try to avoid predators and disease. Many die. Those which survive and ____________ are the ones with the characteristics suited to their ______________. Their genes have enabled them to survive. They pass these on to the next generation. Over a period of time a species changes. This is ___________ by ____________ _____________. Natural selection evolution breed environment vary vary breed environment evolution natural selection