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

Charles DarwinPublished his theory of evolution by natural selection in 1858It was not accepted at firstMany 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 variationLarge numbers die due to predation, competition and disease

Some individuals have characteristics that make them more suited to their environmentThese individuals will survive And breed,Passing on their suitable genesOver time, the organisms change

Natural selection 2

A suit

This is sometimes called….

Survival of the fittest

QuestionWhat 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 2After 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

Antibiotics These drugs are used to kill the bacteria that cause diseaseSometimes mutations in bacteria stop the antibiotics from killing themWhat do you think will happen to these bacteria?

The Giraffe’s neck

Over time, giraffes necks have got longer and longerCan you explain why?Draw a flow chart showing how this is thought to have happened.

SummaryIndividuals 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

evolutionnatural selection