Key
GCSE
words:
acquired,
selection CORE
Biology
1b Evolutionnatural
and Environment
Lets get a grip of Evolution and Natural Selection
through the following interactive video;
http://www.bbc.co.uk/schools/gcsebitesize/science/ede
xcel/environment/evolutionact.shtml
GCSE
Biology 1b Evolution and Environment
CORE
Objective
What are the theories of evolution?
Success Criteria
By the end of the lesson I:
• can explain the two theories of evolution
and who has created them
• can explain evidence that supports one of
the theories
• can identify the evidence for evolution
GCSE
Biology 1b Evolution and Environment
CORE
Who was Charles Darwin?
GCSE
Biology 1b Evolution and Environment
CORE
Natural selection of Finches
This is just one of the examples that got
Darwin thinking about
natural selection.
GCSE
Biology 1b Evolution and Environment
CORE
Summary Darwin's finches
• He noticed that the finches (songbirds) on
the different islands there were fundamentally
similar to each other, but showed wide variations in
their size, beaks and claws from island to island.
• For example, their beaks were different depending
on the local food source.
• Darwin concluded that, because the islands are so
distant from the mainland, the finches that had
arrived there in the past had changed over time.
GCSE
Biology 1b Evolution and Environment
CORE
Darwin’s theory of evolution
The British naturalist Charles Darwin
(1809–1882) later suggested a more
persuasive argument for evolution.
Darwin proposed that evolution took
place through natural and sexual
selection.
Darwin developed his theory of
evolution after noticing close
similarities between certain fossils and
the adaptations of modern day animals
he saw during his round-the-world
voyage on the HMS Beagle.
GCSE
Biology 1b Evolution and Environment
CORE
Controversial research
Darwin knew that in religious
Victorian society his findings
would be controversial and
blasphemous. He was unwilling
to publish and risk his reputation.
However, when Darwin learned
that another British naturalist,
Alfred Russel Wallace, had
proposed an almost identical
theory of natural selection, he
published his findings.
Luckily, a handful of influential scientists were convinced by
Darwin's work and spoke out in public to promote his ideas.
GCSE
Biology 1b Evolution and Environment
CORE
Could Darwin explain everything?
Darwin made extensive use of
specimens and fossil evidence to
explain his theory of evolution,
but because DNA and
genes had not yet been
discovered, he was unable
to explain why traits varied within
individuals or how they were inherited.
Victorian scientists found it difficult to test Darwin’s
theory. For his theory to work, the Earth needed to be
millions of years old, but its age was not known at that time.
In addition, little was known about the process of fossilization
or how to explain gaps in the fossil record.
GCSE
Biology 1b Evolution and Environment
CORE
Lamarck’s theory of evolution
Jean-Baptiste Lamarck (1744-1829) was a French botanist
who believed that species evolved because they inherited
traits acquired through the over or under-use of body parts.
How would this theory explain a
giraffe’s long neck?
The short-necked ancestors of
modern giraffes needed to reach the
leaves on tall trees when food was
scarce.
Over their lifetimes these
giraffes stretched their necks; a
trait which was then passed on
to their offspring.
GCSE
Biology 1b Evolution and Environment
CORE
What evidence for evolution?
GCSE
Biology 1b Evolution and Environment
CORE
Theory of Evolution
The theory of evolution states that all present day
organisms (and many more that are now
extinct) have evolved from simpler organisms
over long periods of time (billions of years)
DARWINs theory is that evolution takes place
through natural selection
LAMARCKs theory is that all organisms originated
from worms and that this was caused by the
inheritance of acquired characteristics
GCSE
Biology 1b Evolution and Environment
CORE
Science vs religion
Read page 116 and answer
Why is it important for students to know
about evolution?
Include
GCSE
– evidence of evolution
- the current scientific theories
- final comment stating your opinion
Biology 1b Evolution and Environment
CORE
Objective
What are the theories of evolution?
Success Criteria
By the end of the lesson I:
• can explain the two theories of evolution
and who has created them
• can explain evidence that supports one of
the theories
• can identify the evidence for evolution
GCSE
Biology 1b Evolution and Environment
CORE