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The Evolution of a Theory
Activity 1: Development of Ideas
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Watch Ch 1-4 of “Darwin’s Dangerous Idea”, noting down any important pieces of evidence
or people that helped Charles Darwin to formulate his Theory of Evolution.
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Read the following information.
Erasmus Darwin
(1731-1802)
Suggested one species
could change into another
but had no evidence for
his theory. Charles’s
grandfather was probably
an important influence in
developing his thoughts on
evolution.
Alfred Russel Wallace
(1823-1913)
Independently developed
and evolutionary theory
based on natural selection.
The publication of his first
paper spurred Darwin to
publish his theory (and 20
years worth of evidence!)
John Baptiste de Lamarck
(1744-1829)
First person to publish a reasoned
theory of evolution. He proposed
that organisms acquired
characteristics over their lifetime
through use (or lack of use) of an
organ or body part. These
developed characteristics are then
passed on to offspring.
Charles Darwin
(1809-1882)
Proposed the theory of
evolution by natural
selection, sometimes
called ‘survival of the
fittest’ – best suited
organisms will survive, and
reproduce.
Gregor Mendel
(1822-1884)
Developed the
fundamentals of the
genetic basis of
inheritance – genes allow
information (that
determines characteristics)
to be passed from parents
to offspring.
From the diagram above, choose one of the contributors to the development of evolutionary theory
(excluding Charles Darwin) and using the internet or other sources, write a paragraph discussing
their role in contributing to Darwin’s ideas.
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Activity 2: Darwin vs Lamarck

Watch BRAINPOP “Charles Darwin”.
1.
Complete the summary below.

Charles Darwin (in 1859) put forward a mechanism to explain evolution as he suggested
that natural ………………... was the process in which species change over ……………
and develop into new ……………….

His ideas were controversial at the time because they conflicted with the accepted
………… belief that all organisms were created at the same …………..

Lamarck (in 1809) had also proposed a theory to explain how populations changed over
time. His theory stated that characteristics that are needed by organisms for their survival
are acquired and those not needed disappear. The acquired characteristics are
………….. on to their offspring. His theory is now known to be false in most cases. E.g.
good tennis players will not necessarily have children who are good tennis players and
clipped poodles never give birth to puppies with clipped hair.
The differences between Darwin’s and Lamarck’s theories are shown in the drawings to the above.
The modern theory of evolution is an extension of Darwin’s theory. Biologists now know about
DNA, genes and chromosomes. Living things are born different because of changes in their DNA
and genes. A change can be caused by rearranging of genes in meiosis or mutations which can be
beneficial to an organism giving it an advantage over others in its environment.
2.
Read through the comparison of explanations below.
A comparison of Lamarckian and Darwinism theories of evolution
Lamarck in 1809 proposed a theory of evolution that stated that animals have organs and structures
that they use and do not use. The ones they do not use would eventually deteriorate and the ones
they do use would be strengthened and passed on to offspring. He also stated that animals would be
able to acquire certain characteristics if they needed them for survival.
Darwin used information that he gathered in his research to formulate his theory of evolution based
on natural selection. He first published his theory in 1859 under the title On the Origin of Species by
Means of Natural Selection.
A. Lamarck’s Theory (1801 – 09)
Sea birds feeding on marine worms all possess
a short beak
B. Darwin’s Theory (1858)
There is variation in the sea bird species with
respect to beak shape
There is an ‘inner want’ in individuals to
possess longer beaks to reach the food.

All individuals grow longer beaks in their own
lifetime.
The acquired characteristics are passed on to
the next generation.
Natural selection and competition for food
favoured longer beaks

Longer-beaked individuals survive at the
expense of shorter-beaked varieties and pass on
their fit characteristics to the next generation.
The fitter long-beaked variety survive to sexual
maturity and pass on characteristics to next
generation.
Eventually, over many generations, only the
long-beaked marine birds survive the
competition
For you to do
The Australian Rabbit-eared Bandicoot possesses large ears which act as large
vascularised radiation surfaces for losing excess body heat to the environment.
These help prevent the animal from overheating in hot environments.
Using the illustrated Lamarckian and Darwinian models on the previous page to guide you, discuss
in point form how: (a) Lamarck; and
(b) Darwin
would have explained the evolution of the bandicoot’s large ears.
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Activity 3: Theory vs Law
In all of your reading (and video viewing), you should have noticed that we refer to ‘The Theory of
Evolution’ not ‘The Law of Evolution’. Explain why Evolution is a theory as opposed to a law.
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