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A little historical background...
• The idea of evolution was not new in the
1800’s. The idea had been around for
centuries.
• The Church was the authority at the time. It
was the Church’s stance that all organisms and
their individual structures resulted from the
direct act of a creator who formed the entire
universe.
Georges Cuvier (1769-1832)
Cuvier
• It was common belief that the world was no
older than 5000 years old.
Cuvier’s Fossils
• Cuvier was a paleontologist and a leading
expert on the anatomy of animals.
• He found that:
1) Each of the layer of rock is characterized by a
unique group of fossils
2) The extinction of species is a common
occurrence.
• He proposed the idea of catastrophism.
Catastrophism
• The theory that catastrophes have periodically
destroyed species in a particular region
allowing species from neighboring regions to
repopulate the area.
John Baptiste Lamark
The Theory of Inheritance of Acquired
Characteristics
• Published in 1809
• Proposed:
1) Microscopic organisms arise continually and
spontaneously from non-living sources.
2) Each species gradually becomes more
complex until they achieve a sort of
perfection.
Lamarck continued….
3) Organisms become progressively better and
better adapted to their environments.
4) The characteristics acquired during an
organism’s life time could then be passed on
to its offspring
• This theory has been disproved.
Charles Darwin (1809-1882)
10 Fun Facts about Darwin
1) Darwin once ate and owl.
2) Darwin wanted to be a doctor but could not
stand the sight of blood.
3) Darwin’s nose almost cost him the voyage on
the Beagle
4) Best Birthday Gift Ever – A Mountain
5) The full title of his book “Origin of the Species”
is actually “The Origin of the Species by means
of Natural Selection or Preservation of Favoured
Races In the Struggle for Survival”
6) Darwin didn’t coin the phrase “survival of the
fittest”.
7) Darwin married his first cousin.
8) Darwin lost his faith in God after his daughter
Annie died at the age of 10.
9) Darwin was a backgammon fiend.
10)The Church of England just recently
apologized to Darwin for their criticism of
him and his theory.
Darwin’s Voyage of Discovery
(1831-1836)
• Darwin was appointed naturalist of the HMS
Beagle.
• The primary mission of the expedition was to
survey the coast of South America.
• Darwin spent hours observing and collecting
thousands of specimens in the diverse
environments that the ship visited.
The Route Taken by the Beagle
Summary of Darwin’s Evidence
• Plants and animals observed in the temperate
regions of South America were more similar to
plants and animals in the South American tropics
than to plants and animals in other temperate
regions of the world.
This lead Darwin to wonder why, if all organisms
originated form a single act of creation, there
existed a distinctive clustering of similar
organisms in different region of the world.
Darwin found fossils of extinct animals
that looked very similar to the animals
present living in the same region
Summary of Darwin’s Evidence
con’t
• Plants and animals living in the Galapagos
Islands closely resembled plants and animals
living on the nearest continental coast.
• This made Darwin wonder why, if all of these
organisms had been created independently
and been placed in the Galapagos Islands,
they so closely resembled organisms on the
adjacent South American Coastline.
Summary of Darwin’s Evidence
con’t
• Species of animals that at first looked identical
actually varied slightly from island to island in
the Galapagos.
• Finches collected in the Galapagos looked
similar to finches from South America but
were, in fact, different species. Finch species
also varied from island to island.
Caused Darwin to wonder why there was such
a diversity in such a small area.
The Galapagos
Islands
Charles Lyell
(1797-1875)
Uniformitarianism
• Charles Lyell was a geologist.
• Developed the theory known as
Uniformitarianism
• Stated that geological processes operated at
the same rates in the past as they do today.
• Rejected the idea of catastrophism
What Darwin learned by Lyell’s
work
• Darwin read Lyell’s work while aboard the
HMS Beagle. After reading his work, Darwin
understood that geological processes that are
slow and subtle can result in substantial
changes. As well, forces that affect change are
the same now as in the past.
• Caused Darwin to wonder why, if the land is
always changing/evolving, organisms cannot
evolve as well.
EVOLUTION
• Any shift in a gene pool
• The relative change in characteristics of
populations that occurs over successive
generations
Darwin’s Theory of Evolution
• Darwin was not the first to propose that
evolution occurs however he was the first
person to gather an array of facts related to
evolution and propose a feasible mechanism
by which evolution might occur.
• On July 1, 1858 the idea of Evolution by
means of Natural Selection was co-presented
by Alfred Russell Wallace and Charles Darwin
at a meeting of the Linnaen Society.
The Origin of the Species
On the Origin of the Species
• On the Origin of the Species was published in
1859.
• In this book, Darwin proposed these 2 main
ideas:
1) All present forms of life have arisen by
descent by modification from a single
ancestral cell.
2) The mechanism for descent is Natural
Selection.
Natural Selection
• The process that drives evolution
• States that the organisms with traits best
suited to their environment are more likely to
survive and reproduce.
Summary of Darwin’s Ideas
1) Organisms produce more offspring than can
survive, and therefore organisms compete for
limited resources.
2) Individuals of a population vary extensively
and much of this variation is heritable.
3) Those individuals that are better suited to
local conditions survive to produce offspring.
4) Processes for change are slow and gradual.