Download Charles Darwin

Charles Darwin
How one man’s
observations and
ideas helped to
change the world
Darwin continued…
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As a young boy, Darwin preferred collecting insects,
hunting and fishing to attending school lessons. He
loved the outdoors.
Darwin’s father and grandfather were both physicians
and hoped Darwin would follow in their footsteps.
Yet Darwin’s time at medical school was short lived as
he was completely nauseated by the operating room
(anaesthetics were not yet in use).
He instead studied to be a clergyman.
Darwin continued…
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On August 24th 1831, shortly after he had
graduated from his studies, Reverend John
Henslow sent a letter to Darwin informing him
that he had been recommended as a naturalist
on a voyage to South America.
Although Darwin had no formal training,
Henslow considered him to be “the best qualified
person I know of …for collecting, observing and
noting anything worthy to be noted in natural
history.”
Darwin continued…
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Darwin accepted the
offer and set sail on
the HMS Beagle on
December 27th 1831.
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The captain of the ship (Captain Robert
FitzRoy) accepted Darwin on board the ship
in hopes that he would find evidence to
support biblical creation.
The voyage of the Beagle
1831 - 1836
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The Beagle set sail on her voyage on 27th December 1831,
with Charles Darwin aboard, and returned to England on
October 2nd 1836. The voyage lasted 5 years.
The mission of the ship was to map the coastline of South
America and everywhere it went Darwin took detailed notes of
what he saw and collected many specimens.
The Galapagos Islands
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Charles Darwin arrived
in the Galapagos, a
group of volcanic
islands off the coast of
Ecuador, South
America on September
15th 1835.
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The observations
Darwin made during his
visit were to be
influential in the
formation of his
scientific theories.
The Galapagos Islands
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During his time on the islands, Darwin collected
specimens of many of the different plants and
animals he observed, and detailed drawings
were also made.
As well as his observations of the species on the
islands, Darwin also wrote descriptions of the
geography and geology of each island in his
diary.
He found that most of the animal species live no
where else in the world, although they resemble
species on the South American mainland (found
this same trend in the Cape Verde islands off the
coast of Africa)
The Galapagos Islands
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Darwin began to wonder why continents that
were very far apart had species that were
entirely different occupying similar ecological
niches? For example, why would species in the
grassland areas of South America be similar to
those of a nearby island rather than those
occupying the grassland areas of Africa?
Darwin observed that each island had its own
unique mixture of plants and animals. These
were often adapted to survive in the different
conditions found on each island.
The Galapagos Islands
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One species which
Darwin wrote many
observations about was
the Galapagos giant
tortoise.
“It was confidently
asserted, that the
tortoises coming from
different islands in the
archipelago were slightly
different in form; and that
in certain islands they
attained a larger average
size than in others”
Darwin’s Finches
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Darwin made detailed studies of one group of birds, the finches,
because of their strong similarities and subtle differences.
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He noticed that the different finch species varied in size, beak size
and shape, and behaviour. He thought that these differences could
be best explained if the finches had gradually become adapted to
suit the conditions on the island they inhabited.
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He presumed therefore that all 13 species of finch found on the
islands must be closely related.
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He also deduced that the individuals with the best set of adaptations
for each island’s habitat would be most likely to survive and breed.
Darwin’s Finches
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Upon his return, Darwin had the bird specimens he had
collected analyzed by ornithologist John Gould.
Gould discovered that the birds were in fact different
species (Darwin did not realize this at first. He thought
he was observing variation within one species)
This suggested to Darwin that a single ancestor had
come from a nearby land and given rise to several
distinct species, especially when isolated on separate
islands.
Importance of adaptation and
survival!
Glyptodon and Megatherium
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While in Patagonia, Darwin discovered fossils of
giant organisms that closely resemble much
smaller modern animals
Upon his return, these fossils were analyzed by
palaeontologist Richard Owen who confirmed
that they were larger versions of armadillo and
sloth which are still found in the area.
Darwin figured these must be ancestral forms of
organisms currently occupying the area
Glyptodon
Armadillo
Megatherium
Sloth
The Origin of Species
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When Darwin returned to England (1836), he
continued to study and collect information about
what he had seen and experienced on his
journey.
About seven years later he presented a paper to
trusted colleagues that proposed his theory of
evolution
However, he knew it would be met with great
opposition and so he continued to gather
evidence and add to his work
The Origin of Species
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In 1858, he received a letter from naturalist
Alfred Russell Wallace who was working in
Indonesia. Wallace had independently arrived
at the same conclusions as Darwin!
Wallace’s work was much more sketchy as he
had written his theory in 2 days, while Darwin
had compiled 22 years of research!!!
Yet Wallace was ready to publish and present
his ideas
The Origin of Species
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Darwin’s friends and colleagues urged him to
present a paper along with Wallace.
On July 1, 1858 both men’s papers were
presented jointly
A year later, in 1859, Darwin published his book
On the Origin of Species By Means of Natural
Selection or the Preservation of Favoured
Races in the Struggle for Life (also known as
the Origin of Species).
The Origin of Species
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The book sold out on the first day.
Why was it so influential?
a) His theory suggested that all living things are
here as a result of descent, with modification,
from a common ancestor
b) His observations could be explained through
his theory of evolution but not through
creationist theories
c) Although evolution was not a new idea, he
was the first person to propose a reasonable
mechanism of how evolution occurred.
The theory still stands today.