Download Evolution

The Theory of Evolution by
Natural Selection
The Theory of Evolution is…
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Arguably, the most important scientific
development of the last 200 years.
A scientific, i.e. evidence based,
theory of the origins of human and
other life forms.
A powerful explanation of the change,
variation, and diversity we see in the
natural world.
An alternative idea to the belief that
human life was designed and created
by God.
Evolution in a Nutshell…
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Life has developed over many millions of
years and began with simple single-celled
creatures
By chance, species mutate and develop into
more complex life forms
All life forms depend on resources so the
survival of new species depends on their
relationship with the environment around
them
A species unsuited to its environment will die
out, but ones that are well-adapted survive
Charles Darwin
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The Theory of Evolution by Natural Selection
is most closely associated the great
naturalist Charles Darwin (1809 – 1882).
Darwin’s Early Life
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Darwin was the son of a doctor but was put
off medicine by watching operations
He had intended to become a minister in the
Church of England but his real interest was
natural history
Like most people at the time, the young
Darwin accepted the view that God had
created different species suited to their
environments and that they did not change
The Voyage of the Beagle
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In 1831 however, he was invited to join a fiveyear voyage around the world on HMS
Beagle…
The Voyage of the Beagle in
Context
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Darwin’s ideas reflected the intellectual
context of the time and the philosophical
challenge to religious authority associated
with Philosophers such as Kant and Hume.
Although many people believed the world was
about 6000 years old, geologists like Darwin’s
friend Charles Lyell were coming to think that
the world was a lot older; e.g. fossils.
If the world were a lot older, then over time,
lots of little changes might add up to big
changes, even new species.
What Darwin Found
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As he travelled, Darwin started thinking about
the geographical distribution of wildlife and
the fossils he found for animals that no longer
existed.
This led him to come up with the idea that life
forms were not fixed but mutable – i.e they
changed or ‘evolved’ over time.
Darwin’s Finches I
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For example, Darwin noticed on the Galapagos
Islands that finches with big beaks lived on an
island with large nuts they could eat, while
small beaked birds lived on an island with lots
of small seeds
Darwin’s Finches II
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Given the fact that the islands were close
together, he came to think that the distribution
of the different Finches was determined by
varying suitability to different environments.
Finches with the ‘wrong’ shaped beak would
not survive, and therefore, would not have
offspring
‘Natural Selection’ I
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What Darwin came to realize was that…
within a species some members have
characteristics better adapted to their
environment than others.
These members will continue to survive and
breed whilst others not as suited to their
environment will die out.
Eventually the characteristic becomes the
norm for the species. This process is called
natural selection.
‘Natural Selection’ II
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As with most scientific ideas, ‘natural
selection’ makes certain assumptions…that
Living things reproduce freely and this results
in competition for resources - food and space.
Animals prey on each other.
Offspring differ slightly from their parents.
Many characteristics are inherited
The longest-living members of a species are
likely to reproduce the most
These are the characteristics most likely to be
passed on to succeeding generations…
Accidential
mutation
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by N______ S________ was
developed by Charles D_____. Challenging the idea that
species are f___ and that humans were c____ by God, it
claims that life _______ over many millions of years and
began with simple single-celled creatures. By ______,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
Darwin
fixed
mutate
created
Selection evolved
Natural
environment
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural S________ was
developed by Charles D_____. Challenging the idea that
species are f___ and that humans were c____ by God, it
claims that life _______ over many millions of years and
began with simple single-celled creatures. By ______,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
Darwin
fixed
mutate
created
Selection evolved
environment
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles D_____. Challenging the idea that
species are f___ and that humans were c____ by God, it
claims that life _______ over many millions of years and
began with simple single-celled creatures. By ______,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
mutate
created
environment
Darwin
fixed
evolved
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are f___ and that humans were c____ by God, it
claims that life _______ over many millions of years and
began with simple single-celled creatures. By ______,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
mutate
created
environment
fixed
evolved
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were c____ by God, it
claims that life _______ over many millions of years and
began with simple single-celled creatures. By ______,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
mutate
created
environment
evolved
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life _______ over many millions of years
and began with simple single-celled creatures. By ____,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its __________ will
die out, but ones that are well-_______ survive.
chance
adapted
mutate
environment
evolved
resources species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By ____,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its _________ will
die out, but ones that are well-______ survive.
chance
adapted
mutate
environment
resources
species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species ______ and develop into more complex life
forms. All life forms depend on ________ so the survival
of new _______ depends on their relationship with their
surroundings. A species unsuited to its _________ will
die out, but ones that are well-______ survive.
adapted
mutate
environment
resources
species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species mutate and develop into more complex life forms.
All life forms depend on ________ so the survival of new
_______ depends on their relationship with their
surroundings. A species unsuited to its _________ will
die out, but ones that are well-______ survive.
adapted
environment
resources
species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species mutate and develop into more complex life forms.
All life forms depend on resources so the survival of new
_______ depends on their relationship with their
surroundings. A species unsuited to its _________ will
die out, but ones that are well-______ survive.
adapted
environment
species
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species mutate and develop into more complex life forms.
All life forms depend on resources so the survival of new
species depends on their relationship with their
surroundings. A species unsuited to its _________ will
die out, but ones that are well-______ survive.
adapted
environment
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species mutate and develop into more complex life forms.
All life forms depend on resources so the survival of new
species depends on their relationship with their
surroundings. A species unsuited to its environment will
die out, but ones that are well-______ survive.
adapted
Evolution: Task 1
Copy and Complete the following:
The Theory of Evolution by Natural Selection was
developed by Charles Darwin. Challenging the idea that
species are fixed and that humans were created by God,
it claims that life evolved over many millions of years and
began with simple single-celled creatures. By chance,
species mutate and develop into more complex life forms.
All life forms depend on resources so the survival of new
species depends on their relationship with their
surroundings. A species unsuited to its environment will
die out, but ones that are well-adapted survive.
‘The Origin of Species’
Although Darwin wrote out a version of his
‘species theory’ in 1842, he did not publish his
ideas for nearly two decades.
Q. Why do you think Darwin delayed publishing
ideas for so long?
 By 1858, however, Darwin had become aware that
another naturalist, Alfred Wallace, working in
Malaya, had developed very similar ideas.
 The two men presented their ideas to the Linnean
society in 1858 but attracted little interest.
 In 1859, Darwin published ‘On the Origin of
Species’, which set out his ideas in detail.
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The Impact of Darwin’s Ideas
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The initial response to the Origin of Species
was relatively muted.
This reflected the fact that many scientists at
the time were also religious.
The division between science and belief did
not really exist.
Some scientists, even Darwin himself perhaps,
retained a faith in God
But as the implications of Darwin’s theory
became appparent, so the controversy grew.
The Implications of Origins I
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Darwin’s Christian faith had already begun to
fade before his eldest daughter Annie died at
the age of 10 in 1851.
But Darwin probably delayed publishing his
theory because he saw the damaging social
implications for a still dominant Christianity.
He might even been wary of blasphemy laws.
Why?
Because his theory suggested that life on
earth developed randomly and blindly.
It removed any need for a designer/creator
God!
The Implications of Origins II
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Most disturbingly, for supporters of the
religious view, Darwin argued that while
human beings had ‘noble qualities’ and ‘godlike intellect’, we shared a common biological
ancestry with the so-called ‘lower’ species.
Far from a ‘crown of creation’, we were simply
a newer, more successful form of primate; i.e.
humans are just well-adapted, hairless apes.
Task 2
Q.1 Why did Darwin’s theory pose a threat to
existing religious ideas about the origins and
status of human life?
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Because his theory suggested that life on earth
developed randomly and blindly, it removed the
need for a creator God!
While human beings might have ‘noble qualities’
and ‘god-like intellect’, Darwin argued that we
share a common ancestry with the so-called ‘lower’
species: i.e we are simply a newer, more
successful form of primate; well-adapted, hairless
apes.
Problems in Darwin’s Theory
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Another reason, Darwin might have held back
on his theory may have been the fact that there
were some unresolved issues with it.
Crucially, he could not demonstrate the
process of evolution, only infer it from the
evidence available to him.
It was based on circumstantial evidence - e.g.
fossils, the variety and location of species rather than empirically verified experiments.
He also recognise that he had not identified
the mechanism of evolution itself.
How were traits developed and passed on?
DNA – The Building Blocks of Life
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This issue was addressed nearly a century
after the publication of Origins with the
discovery of DNA – deoxyribonucleic acid.
Hitherto, people saw it as self-evident that we
inherited some qualities from our parents.
But other qualities were not.
The discovery of DNA by Crick and Watson in
the 1950s enabled scientists to explain exactly
how this happened .
Mutations
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Some qualities are developed over a lifetime
and are not passed down over time – e.g. skills
like playing an instrument have to be learnt
But the physical potential of all living things is
determined by genes passed on in DNA.
Every now and then a mutation occurs.
If that mutation gives an advantage in passing
on DNA then the mutation survives and
becomes the norm
Task 3
Q. What were some of the issues with
Darwin’s theories initially?
Darwin could not demonstrate the process of
evolution through experiments, only infer it from
the circumstantial evidence available to him,
e.g. fossils along with the variety and
distribution of species. Neither had he identified
the mechanism of evolution itself; how traits
were developed and passed on.
Task 4
Q. How did other scientists develop the
Theory of Evolution to address these
issues?
Although people saw it as self-evident that we
inherited some qualities from our parents, it was
only after the the discovery of DNA –
deoxyribonucleic acid – by Crick and Watson, that
scientists could explain how it happened. The
physical potential of all living things is determined
by genes passed on in DNA. Every now and then a
mutation occurs. If that mutation gives an
advantage in passing on DNA then the mutation
survives and becomes the norm
Evolutionary Theory Now
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Modern Darwinians argue that life on Earth
began in a ‘primordial soup’ where inorganic
elements, subjected to ultraviolet light or
electrical storms, underwent a chemical
change to organic molecules.
Eventually these organic molecules came
together to form simple, single-celled
organisms able to replicate or reproduce
themselves.
Over time, these mutated into ever more
complex forms.
The Darwinian View of Humans
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Most importantly, proponents of the Darwinian
view such as Richard Dawkins argue that the
process of evolution is random or blind.
All that is needed is lots of time.
Other than passing on our genetic
inheritance they say there is no
purpose to it; no guiding hand, no design, no
God!
This contradicts the religious view that
humans have a special place and purpose in
the universe
The Darwinian View of Humans
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Dawkins et al would argue that humans
are not ‘special’ but a successful
accident or mutation.
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In the future, however, (man-made?)
changes in the environment and a failure
to adapt could lead humans to die out
like the dinosaurs, and be superseded by
another form of life.
Evolution: Task 5
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If the Theory of Evolution is correct, the development
and location of the various species on Earth has
been shaped by the way new ‘mutations’ help or
hinder survival and the ability to generate offspring.
For example…
…the shape of a bird’s beak will determine what food
they can eat. They can only survive in environments
where the right kind of food is available
…the ability some animals have to run very quickly
enables them to hunt and/or evade predators.
…Polar Bears’ fur provides camouflage and warmth
in icy areas where other animals cannot survive.
Evolution: Task 5
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Pick 3 of the following qualities and write a short
paragraph discussing how they might give
humans an evolutionary advantage:
Skin colour
Strength
Courage
Beauty
Wealth
Language
Intelligence
Men Driving Too Fast
The Theory of Evolution by Natural
Selection - Strengths
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It is based on and supported by a massive body of
scientific research and evidence which links a
range of scientific disciplines – biology,
chemistry, physics, geology etc.
It provides a convincing working explanation of
observable realities such as…
- The astonishing biodiversity of our planet.
- Similarities and differences between species.
- Mass extinctions and other major changes in the
natural history of our world.
- The development of human beings.
The Theory of Evolution by Natural
Selection – Strengths II
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Recent developments in Science e.g. the
discovery of DNA and the development
of genetics support Darwin’s insight.
Our awareness of how important DNA is
has already brought medical benefits.
The idea that the process is blind
removes the need to explain the origins
of a supernatural creator God.
It puts humans in charge their own
destiny!
The Theory of Evolution by Natural
Selection – Limitations
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Much of evolutionary theory is based on
circumstantial evidence and inference.
Evidence could be interpreted in other ways.
There are ‘gaps’ in the theory and the
evidence supporting it…
- E.g. incomplete fossil record which does not
show intermediate species or ‘missing links’.
Some complex life forms exist as parts of
complete systems in which an intermediate
form would not work.
The Theory of Evolution by Natural
Selection – Limitations
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Critics say it does not answer questions about
the meaning and purpose of human life.
The best that Darwinians such as Richard
Dawkins can offer is the idea of the ‘selfish
gene’
i.e. that life forms exist only to pass on their
genetic information, their DNA.
It seems to undermine the power and authority
of religion without offering any moral
guidance as to how we should try to live.
The Origins of Human Life: Are
Science and Religion Compatible?
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The Bible sets out a special, God-given role and
purpose for humans.
For Christians, our lives are made meaningful by
our relationship with God.
If the Theory of Evolution is true it calls these things
into question.
How might we think about the relationship between
science and belief in the light of Darwinian ideas?
Evolution v Revelation
There are three basic positions or possible
responses to this issue.
1. Evolution contradicts revelation – the
science must be rejected.
2. Revelation contradicts evolution –
Christianity must be rejected.
3. Revelation and Evolution both
contribute to a full understanding of the
origins of human life.
1. Rejecting Evolution Creationism
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As with the debate regarding the creation of
the Universe, Creationists refuse to
acknowledge the truth of anything that
contradicts scripture.
Accepting the Bible as fact is an act of faith.
If it is not in the Bible it cannot be true.
Evidence and argument are irrelevant.
But not all Christians are comfortable with
the circular argument that the truth of the
Bible proves the truth of the Bible…
Rejecting Evolution – Intelligent
Design
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Some Christians, use science as a means to
reject evolution, and propose an alternative –
INTELLIGENT DESIGN!
Using the Teleological argument (cf. Paley) they
highlight the weaknesses in evolutionary theory.
In particular, they reject the idea that the
development and survival of species is down to
the mechanism of chance.
They also highlight what they see as gaps and
flaws in the evidence used to support
evolutionary theory.
Rejecting Evolution – Intelligent
Design II
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For example, they point out the
‘irreducible complexity’ of some
organisms.
They argue that the step by step
process does not add up.
E.g. a partly evolved wing is
impossible to conceive without all
the other parts being present.
Or, they argue that many mutations
are harmful and do not necessarily
lead to whole new species.
Intelligent Design - Strengths
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Uses evidence-based science, to argue
against the chance mechanism.
Addresses possible flaws and gaps in
evolutionary theory.
Avoids the extremes of literalist
understandings of the Bible.
Ties in with liberal Christian approaches to
the interpretation of the Bible – God still the
designer!
Intelligent Design - Limitations
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Scientific argument is complicated and
beyond the reach of ordinary people.
Implies Biblical creation stories are not
enough.
As an alternative to Darwinian ideas, it is
really an attempt to defend faith in God.
It does not really overturn evolutionary
theory or prove the existence of God
2. Rejecting Christian Belief –
Scientific Materialism
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Many scientific materialists see evolution as fact
rather than theory because of the weight of the
supporting evidence, incomplete as it may be.
It contradicts the Bible, therefore the Bible is
wrong – there are other explanations for what
was written – scripture is obsolete.
Evolution is the best explanation we have for the
origin and development of life on Earth.
Intelligent design is not a scientific theory but a
religious one – it is an argument for the
existence of God which is faith-based rather
than fact-based, i.e. bad science.
Belief and Science: Either Or?
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On the face of it, the relationship
between Christian Revelation based in
the scriptural authority of the Bible and
the modern scientific Theory of
Evolution is irreconcilable.
Yet there are many scientists who are
Christians able to accept both
Christian teachings and the findings of
Darwinian evolutionary theory…
3. Revelation and Evolution both
contribute to a Full Understanding
of the Origins of Human Life
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Some scientists reject the aggressive
atheism of scientists such as Richard
Dawkins.
They argue that science has its
limitations, and that human origins can
only be understood fully by utilising
science in conjunction with Philosophy
and Religion.
Revelation and Evolution as
Complementary
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Scientists such as Joel de Rosnay, point out
the reductionist tendencies of science.
Highlighting the limits of science as a way of
understanding ‘life’, they suggest that
religion and science should be seen as
complementary rather than conflicting
explanations for the origins and
development of life.
They understand evolution as the
mechanism through which God created life
on Earth according to the laws of nature,
also established by Him.
Revelation and Evolution as
complementary
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They understand Genesis as a ‘myth’, as a
symbolic account of creation.
It is not intended as science but as a way
of ‘revealing’ the nature of our
relationship with God.
They would say that our genetic similarity
to other primates does not negate our
‘specialness’ but reminds us of our
responsibilities to look after the natural
world created by God.
Evolution is just another form of God
revealing Himself to us!
Revelation and Evolution as
complementary
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For such Christians, Evolution is about the
physical dimension of life on Earth.
For them, the Theory of Evolution has little to
say about the spiritual aspects of living.
That is the role of religion, to develop our
spiritual relationship with the universe.
If we are ‘special’, and created in the image of
God, then the curiosity and intelligence that
has led to the development of evolutionary
theory is part of God’s plan for us…
…to become more fully human.