B1 Chapter 7 EvolutionThe Final Chapter!

Title for today:

Theories of Evolution

You need: Notes on Lamarck’s Theory and Darwin’s theory.

Theories of Evolution

Learning Objectives:• To understand what is meant by the ‘theory of

evolution’• to explain why fossils are important• To have an awareness of how old the Earth is

What is a theory?

• A scientific theory is an explanation of the natural world that has been repeatedly confirmed through observation and experiment

What is the theory of evolution?

The theory of evolution states that:All species of living things that exist today(and many more which are now extinct)have evolved from simple life forms, whichfirst developed more than 3 billion years ago. How old is the Earth?The Earth is 4.5 billion years old

How do we know evolution happened?

• http://www.youtube.com/watch?v=ewtw_nZUIDQ

Fossils as evidence

• What are fossils?• How can they provide evidence for evolution?• Why do not provide complete evidence for

this theory?

What drives this change?

•A fast runner on hard ground•It has one toe forming a hoof

•Looks more like the modern horse with one hoof

•Slightly bigger•Walks mainly on one toe

•Has 3 toes on the ground•To run faster on drier ground

•Small•Lives on swampy land•Toes are well spread

How did the giraffe get such a long neck?

Lamarck’s Theory of Evolution

• He believed that all creatures were linked by a ‘fountain of life’

• And animals inherited acquired characteristics

• The characteristics that help that organism to survive are passed to their offspring

• So if your parents are body builders then you are born that way

Why was Lamarck’s theory wrong?

• It cannot account for all the observations on Earth

• His theory implies that all organisms would gradually become complex

• Simple organisms would disappear (this is not the case)

Darwin’s Theory of Evolution

• Darwin set out in 1831 on a voyage on HMS Beagle

• At the Galapagos islands he saw different features on a variety of finches

Darwin’s Theory of Evolution

• All living organisms have evolved from simpler forms

• Evolution has come about by a process called natural selection

• Only those most adapted to their environment will survive, reproduce and pass on their genes.

• Survival of the fittest

Darwin did not publish his theory for many years.

Why reasons could there have been for this?

Can you explain what this diagram represents? How did it happen?

Evolutionary Trees

Evolutionary Trees

Evolutionary Trees

1. Why is Homo floreiensis not connected to any other species?

2. From which common ancestor did homo sapiens and homo erectus evolve?

3. Lines linking Homo ergaster and homo habillis join around how many years ago? What does this represent?

4. Who was the closest ancestor of Australopithecus africanus?