Download PowerPoint Presentation - The Implications of Evolution

“Platonic Ideal”
Scala Naturae: Great Chain of Being
Implications of the Great Chain of Being
• Since God is perfect, his creation must be
perfect
• A gradation must exist from inanimate
objects through higher forms, complete with
no gaps
• No gaps in the chain: no extinction, no new
forms
William Paley
(1743-1805)
• Natural Theology: or,
Evidences of the Existence
and Attributes of the Deity,
Collected from the
Appearances of Nature.
(1802)
• “the watch must have had a
maker”
18th Century began “The Age of
Enlightenment”
• Newton’s explanations of physical
phenomena lead to an increasingly scientific
view
• Faith in progress and the power of reason
• The progress in geology suggested the Earth
has undergone many changes and is very old
Charles Lyell, Principles of Geology
(1830)
Championed the idea of
Uniformitarianism: the forces
molding the planet today have
operated continuously throughout
its history.
The formation of Earth's crust took
place through countless small
changes occurring over vast periods
of time, all according to known
natural laws.
The Earth is very old
Lamarck’s Theory of Evolution
I. Life originates through spontaneous generation
then progresses up the great chain by moving
along a set path (the different organisms we see
today just began on this path at different times).
II. The production of new organs is brought about
by need or want (an internal driving force).
III. Acquired new organs, or changes in
organization, are passed on to future generations -> adaptation.
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Evolution of the long-necked giraffe
Charles Darwin(1809-1882)
• Brief Biography:
– Went to school in Edinburgh to study medicine like
his father
– Switched to the study of clergy at Cambridge
– After school, Darwin signed on as ship’s naturalist
on the HMS Beagle
3 Influences on Darwin:
- Charles Lyell, Principles of Geology (1830)
- Thomas Malthus, Essay on the Principle of Population (1798)
- Voyage on the Beagle
Thomas Malthus, Essay on the
Principle of Population (1798)
The rate of human population growth is greater than the
rate of increase of food supply --> will lead to famine
Alfred Russell Wallace (1823-1913)
Avid Naturalist: traveled to Malaysia and
South America, collecting specimens to sell in
order to finance his trips
In 1858, while suffering from a bout of
Malaria, came up with the theory of natural
selection independently of Darwin
Sent a few pages of “On the tendency of varieties
to depart indefinitely from the original type”
to Darwin -->
Wallace and Darwin jointly present their ideas to
the Linnaean Society in London
1859: Darwin publishes On the Origin of Species by
Means of Natural Selection, or the Preservation of
Favored Races in the Struggle for Life
• Major Theses of The Origin
– All species, living and extinct, have descended without
interruption from one or a few original forms of life
– The process of natural selection is the primary cause for descent
with modification