Chapter 2 Outline
The Development of Evolutionary Theory
 Brief History of Evolutionary Thought
 Natural Selection in Action
 Constraints on Nineteenth-Century Evolutionary
Theory
 Opposition to Evolution
 A change in the genetic structure of a
population.
 Also refers to the appearance of a new
species.
 Often controversial, some religious views
hold that evolutionary statements run counter
to biblical teachings.
Evolution is a
Theory
 The theory has been supported by a
mounting body of genetic evidence.
 The theory has stood the test of time.
 The theory stands today as the most
fundamental unifying force in biological
science.
Pre-scientific View
 In the middle ages, the predominant world was stasis,
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the world was fixed and unchanging. (Fixity of
Species)
The great chain of being held that life was arranged
from simplest to most complex.
It was believed that the earth was “full” and nothing
new could be added.
The world was seen as the result of a grand design God’s design.
The work had been finished around 4004 B.C.
according to archbishop James Usher of Ireland (1581
– 1656)
The Great Chain of being transferred
to society as:
 God ~ Jesus
 Monks and Nuns
 King – Archbishop
 Citizens
 Nobility
 Free Farmers
 Bishops
 Fishermen
 Priests
 Tenant Farmers
 Knights
 Beggars
(Sovereign rule was given to
the king from God and the
importance of life followed
this list)
 Slaves
(Remember most did not read
and write, so were told what
the bible said, explaining
their place in life,)
The Scientific Revolution
 Discovery of the new world challenged
fundamental views about the planet.
 Exposure to new plants and animals
increased awareness of biological diversity.
The Scientific Revolution
 Copernicus challenged the idea
that the earth was the center of the
universe ~ heliocentric. (1473 – 1543)
 Galileo’s work supported the
idea that the universe was a place
of motion. (1564- 1642)
 Keppler, Descartes and Newton established
the laws of physics, motion and gravity.
The Path to Natural Selection
 John Ray provided first definition
of the concept of species and genus.
(1628-1705)
 Carolus Linnaeus developed system
of classification and the basis for
taxonomy. (1707 – 1778)
 Comte de Buffon stressed the
importance of change in the universe
and the environment as an agent of
change. (1707 – 1788)
The Path to Natural Selection
 John Baptiste Lamarck was the first
scientist to produce an explanation for
the evolutionary process. (1744 – 1829)
 Georges Cuvier introduced the concept
of extinction and the theory of
catastrophism. (1769-1832)
 Charles Lyell developed the theory of
uniformitarianism. (1797 – 1875)
 Thomas Malthus wrote about
relationship between food supply
and population increase.
(1766 – 1834)
Charles Darwin
(1809-1882)
 Ideas were formed while serving as a
naturalist on the voyage of the HMS
beagle.
 Darwin saw the importance of
biological variation within a species.
 Recognized the importance of sexual
reproduction in increasing variation.
 By 1844, Darwin had complete the
work that he would publish fifteen
years later.
Alfred Russell
Wallace
(1823-1913)
 A naturalist who worked in South America
and Southeast Asia.
 Suggested species descended from other
species and new species were influenced by
environmental factors.
 Presented paper on evolution and natural
selection to the Linnean Society of London
jointly with Darwin.
Processes of Natural Selection
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Species can produce offspring at a faster rate than
food supplies increase.
There is biological variation within all species.
In each generation, more individuals are produced
than can survive.
Individuals that possess favorable traits or variations
are more likely to survive and produce offspring.
Environmental context determines whether a trait is
beneficial.
Traits are inherited and passed on to the next
generation.
Variations accumulate over long periods of time, so
later generations may be distinct from ancestral ones.
As populations respond to pressures over time, they
may become distinct species, descended from a
common ancestor.
Evolutionary Change
Through Natural Selection
A trait must be inherited to have importance
in natural selection.
2. Natural selection cannot occur without
variation in inherited characteristics.
3. Fitness is a relative measure that will
change as the environment changes.
1.
Opposition to Evolution
Debate has continued for almost 150 years, currently
only a U.S. debate.
The genetic evidence for evolution is
Indisputable
Evolution is science fact, it is NOT based on beliefs.
Often the knowledge needed to understand it is not
known or pursued by those who oppose it.
Most dialogues in opposition deny evolution without
substituting viable scientific theories to support their
alternative claims