The Development of Evolutionary Theory

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Chapter 2

• The Development of Evolutionary Theory

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Evolution?

• Brian Malow http//www.youtube.com/watch?vOhvh47v
  Tp34featurerelated

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Introduction to the Subject of Evolution

• Evolution is the most fundamental of all
  biological processes, but one of the most
  misunderstood.
• Humans evolved from a species that lived some
  6-8 million years ago (mya), not monkeys or
  chimpanzees.

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• Evolution takes time hence, the appearance of a
  new species is rarely witnessed
  (microevolutionary changes occur, however see
  Chapt. 1)
• The subject of evolution is controversial,
  especially in the U.S. because of conflicting
  spiritual teachings

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Evolution Is a Theory

• The theory has been tested and subjected to
  verification through accumulated evidence (and
  has not been disproved)
• The theory of evolution has been supported by a
  mounting body of genetic evidence.
• The theory has stood the test of time.
• The theory continues to grow.

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A Brief History of Evolutionary Thought

• Evolutionary principles were developed in western
  Europe, made possible by scientific thinking
  dating to the 16th century.
• Western science, however, borrowed ideas from
  Arab, Indian, and Chinese cultures where notions
  of biological evolution had already developed.
• It was the theory that was new.

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Natural Selection

• Natural selection in the theory of evolution
  refers to genetic change or changes in the
  frequencies of certain traits in populations due
  to differential reproductive success between
  individuals.
• The most critical mechanism of evolutionary
  change, first explained by Charles Darwin
• Same conclusions were independently reached by
  Alfred Russel Wallace.
• A predominant feature of European worldview was,
  however, that all forms of nature never changed.

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Fixity of Species

• The notion that species, once created, can never
  change.
• An idea opposed to theories of biological
  evolution.
• To challenge the idea was to challenge the
  perfection of Gods design.

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The Scientific Revolution

• Came with the discovery of the New World,
  introducing new ideas and challenging fundamental
  views about the planet.
• Exposure to new plants and animals increased
  awareness of biological diversity.

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EVOLUTIONTHE INSPIRATIONSJOHN RAY 1627-1705

• John Ray, a minister educated at Cambridge
  University, developed the concept of species.
• He recognized that groups of plants and animals
  could be differentiated from other groups by
  their ability to mate with one another and
  produce offspring.
• He placed such groups of reproductively isolated
  organisms into a single category, which he called
  the species.

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EVOLUTIONTHE INSPIRATIONSCAROLUS LINNAEUS
1707-1778

• Carolus Linnaeus, a Swedish naturalist who
  developed a method of classifying plants and
  animals.
• In Systema Naturae, first published in 1735, he
  standardized Rays use of genus and species
  terminology and established the system of
  binomial nomenclature.
• He added two more categories class and order.
• Linnaeus four-level system became the basis for
  taxonomy.

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EVOLUTIONTHE INSPIRATIONSCAROLUS LINNAEUS
1707-1778
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EVOLUTIONTHE INSPIRATIONSERASMUS DARWIN1731-1802

• Erasmus Darwin, Charles Darwins grandfather
• Physician, poet, and leading member of an
  intellectual community in England
• In a poem, expressed the view that life had
  originated in the seas and all species descended
  from a common ancestor.
• Charles read his grandfathers writings, but how
  much he was influenced by them is unknown.

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EVOLUTIONTHE INSPIRATIONSJEAN-BAPTISTE LAMARCK
1744-1829

• Jean-Baptiste Lamarck developed a theory to
  explain the evolutionary process, known as the
  inheritance of acquired characteristics.
• An example is the giraffe having stripped the
  leaves from the lower branches of a tree, the
  animal tries to reach leaves on upper branches.
• The neck becomes slightly longer.
• The longer neck is passed on to offspring.

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