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
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
Natural selection 1
Individuals within a species show a lot of variation
Large numbers die due to predation, competition and disease
Some individuals have characteristics that make them more suited to their environment
These individuals will survive
Passing on their suitable genes
Over time, the organisms change
Natural selection 2 A suit
This is sometimes called….
Survival of the fittest
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
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
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
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?
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.
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 ____________ _____________.