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Chapter 22

BISC208 Chapter Notes - Chapter 22: Goose Bumps, Special Creation, Coccyx

Biological Sciences
Course Code
Benjamin Rohe

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Chapter 22 – Evolution by Natural Selection
Natural selection explains how populations become well suited to their environments
over time
Populations of organisms evolve
The heritable characteristics of populations change over time
Special Creation claimed
oAll species are independent (not related to each other)
oLife on Earth is young (perhaps just 6000 years)
oSpecies are immutable (incapable of change)
Scientific theories usually have two components
Plato claimed that every organism was an example of a perfect essence, or type, created
by God, and that these types were unchanging
oPhilosophers and biologists refer to this as typological thinking
Aristotle ordered the types of organisms known at the time into a linear scheme called
the great chain of being
oProposed that species were fixed types organized into a sequence based on
increased size and complexity
Lamarck claimed species change through time via the inheritance of acquired characters
oAn individual develops as its phenotype changes in response to challenges posed
by the environment and it passes these phenotypic changes onto offspring
Ex. Giraffes develop long necks as they stretch to reach leaves high in
treetops, and they then produce offspring with elongated necks
Evolution occurs because traits vary among the individuals in a population and because
individuals with certain traits leave more offspring than others do
Theory of evolution was revolutionary because
oIt suggested that species change through time and are related by common
oIt replaced typological thinking with population thinking
oIt was scientific
Pattern component of the theory of evolution by natural selection makes two
predictions about the nature of species:
oSpecies change through time
oSpecies are related by common ancestry
Evidence for the Earth’s vast age began to mount in the late 1700s with James Hutton’s
proposal of the principle of uniformitarianism
oIdea that geological processes occurring today are similar to what occurred in
the past
Earth is about 4.6 billion years old, and the earliest signs of life appear in rocks that
formed 3.4-3.8 billion years ago
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