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The Theory of
Evolution
by Natural
Selection
Part 1: Background
Charles Darwin
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Born: 1809
(over 200 years ago)
Father was a minister.
Studied medicine &
theology at Cambridge
University, England..
Preferred natural
history
Charles Darwin - 2
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1831 – Darwin was
hired as a naturalist
aboard the HMS
Beagle.
5 years on the ship –
a journey to chart
sections of the coast
of South America.
He was seasick for
most of the voyage.
Source: http://darwin-online.org.uk/converted/scans/1890_Voyage_F59(online)/1890_Voyage_F59_022.jpg
HMS Beagle route map (5 year voyage)
Charles Darwin - 3
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Darwin’s job was to
collect biological
specimens of the plants
and animals that lived
in these places and
keep records of what he
found.
He did a remarkable
job of it, sending back
over 5,400 specimens
to naturalist professors
in England.
Notice on some fungi collected by C. Darwin, Esq., in South America and the Islands
of the Pacific. Annals and Magazine of Natural History 9: 443-448
Source: http://darwin-online.org.uk/graphics/SpecimenIllustrations.html
Charles Darwin - 4
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Darwin became interested
in the geographical
distribution of organisms.
Why did species living
today in the jungles and
grasslands of South
America look more like
fossils of S. America than
the jungles and grasslands
of Africa?
Darwin draws the first PHYLOGENIC TREE
Charles Darwin - 5
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“When on board H.M.S. ‘Beagle’
as naturalist, I was much struck
with certain facts in the
distribution of the inhabitants of
South America, and in the
geological relations of the present
to the past inhabitants of that
continent.
These facts seemed to me to throw
some light on the origin of
species.…”
Alfred Russell Wallace
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A contemporary and friend of
Darwin’s, was coming up with the
same ideas and getting ready to
publish his work. He sent Darwin a
copy of a paper he wrote and was
going to publish.
This prompted Darwin to panic and
he worked frantically for a year to
publish his work earlier than he
wanted to.
A paper that Darwin wrote 15 years
earlier established that it was his
original idea.
Wallace agreed that Darwin should
be credited.
Charles Darwin - 6
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1859 – On the Origin of
Species by Means of Natural
Selection
Proposed the idea of
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“Descent with Modification”.
Did NOT use the term
“Evolution”,
used the term “transmutation”
of species.
What did he mean by
descent?
What is a descendant?
Wordle of the entire text of the Origin of Species
Highest frequency words are larger
http://www.Wordle.com
Source: http://etext.virginia.edu/toc/modeng/public/DarOrig.html
Think. Answer the questions below
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What did Darwin mean by descent?
What is a descendant?
What is an ancestor?
What did he mean by modification?
What does it mean to modify something?
What did he mean by natural selection?
What is nature?
What does it mean to select something?
Charles Darwin - 7
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1859 – On the Origin of
Species...After 5 years on
board the Beagle, and 20
years of dedicated study,
Darwin’s idea was:
All organisms on earth are
related to each other
through descent from some
common ancestor.
Species alive today are
descendants of species that
came before.
Darwin’s illustration of trimorphic flowers
of Lythrum salicaria in Forms of Flowers, 1877
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Most importantly,
Darwin provided a
plausible explanation
for how that could
happen:
Natural Selection
On the Scelidothere (Scelidotherium leptocephalum, Owen).
[Read 18 December 1856] Philosophical Transactions of the
Royal Society of London 147: 101-110.
http://darwin-online.org.uk/graphics/SpecimenIllustrations.html
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Darwin’s ideas were
controversial at the
time of publication,
many scientists
disputed his ideas,
and Darwin was
ridiculed in the press.
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However… His ideas have stood
every scientific test put to them,
new evidence gathered since
Darwin’s day continues to support
his idea.
You have looked at a tiny portion
of this body of evidence
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Morphological
Embryological
Geological
Fossils
Molecular
DNA
amino acid sequences in common
proteins, and radiometric dating.
Scientists today accept descent
with modification by natural
selection as a fact based on the
enormous body of evidence.
Charles Darwin - 11
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Why do you think
Darwin waited to
present his ideas to
the public?
Why was he
criticized?