Download History of Evolutionary Thought (student note)

SBI 3U
Ms. Girvan
Date: ___________________
History of Evolutionary Thought
I. Early Philosophies
- Plato believed that organism existed in an unchanging ideal form
- Aristotle categorized all living things and felt that organisms fit into an orderly
scheme called the ______________________________ (Ladder of Nature)
- Aristotle believed that all organisms that ever would exist were already created
permanent and perfect
II. George-Louis Leclerc, Comte de Buffon (1707-1788)
- publicly challenged the idea that life forms were unchanging
- noted similarities between humans and apes (speculated on
______________________________________________)
- suggested species change over time and the Earth was much older than
_________________ years
III. Georges Cuvier (1769-1832)
- developed science of ________________________________ (study of ancient life
through examination of fossils)
- found each layer (stratum) of rock is characterized by a unique group of fossil
species
- also found that deeper fossils were more dissimilar to modern life
- discovered that new species appeared and others disappeared over the passage
of time (showed that species could become extinct)
- proposed theory of catastrophism
 Catastrophism
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IV. Charles Lyell (1797-1875)
- geologist who rejected catastrophism
- proposed theory of uniformitarianism based on geologist James Hutton’s work
 Uniformitarianism
- theorized that slow, subtle processes could happen over a long period of time and
could result in substantial changes
V. Jean-Baptiste Lamarck (1744-1829)
- believed that species increased in complexity over time, until they achieved a level
of perfection
- hypothesized that organisms would become progressively better adapted to their
environments
- also suggested body parts not used would eventually disappear
 Inheritance of Acquired Characteristics
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this theory was ultimately disproved, especially after discoveries were made about
genetics and how traits were inherited
V. Charles Darwin (1809-1882)
- in 1831, he set off on a five year voyage on the H.M.S Beagle as the ship’s naturalist
- he collected specimens and took observations of the organisms he encountered
- some of his observations Table 8.1 (p.329)
- flora and fauna of different regions were distinct from those in
England and Europe
- fossils of extinct animals that looked very similar to living animals
- finches and other animals on Galapagos Islands closely resembled animals he
had observed on west coast of South America
- Galapagos species (tortoises & finches) looked identical at first, but actually
varied slightly between islands
VI. Darwin and Wallace – The Theory of Evolution by Natural Selection
- Alfred Russel Wallace (1823-1913) reached conclusions similar to Darwin
- both naturalists suggested that organisms tend to produce more offspring than can
survive
- some organisms would be more “fit” to survive than others, and the fittest organisms
would pass on those traits to their offspring
- competition for limited resources between individuals of the same species would
select for individuals with favourable traits - “survival of the fittest”
VII. The Origin of Species – by Charles Darwin
-
published in 1859
-
proposed that all life descended from an unknown organism
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descendants spread out and developed adaptations that helped them better
survive in their local environments
Main ideas:
o Organisms produce more offspring than can survive, therefore there is
competition for resources (food, space, etc…)
o Individuals of a population vary extensively, and much of this variation is
heritable
o Individuals who are better suited to local conditions survive to produce
more offspring
o Process for change are slow and gradual
-
coined the term natural selection:
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Darwin did not use the term evolution in the original edition of his book
-
he spoke of descent with modification as he felt evolution implied progress
-
natural selection has NO set direction
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