Chapter 2 -- BIOLOGY: From Natural Philosophy to Darwin

review questions


  1. Two views of the history of life: 
    1. Special creation
      1. Immutability of species
      2. Each species is separately created
      3. Earth and life are young
    2. Descent with Modification
      1. Species change through time
      2. Species derive independently from common ancestors
      3. Earth is very old

2.1 2.2 Nature and Evoluton Before Darwin (p 30)

  1. 2.1 - Nature Before Darwin (p. 30)
    • Long before Darwin, naturalists Carl Linnaeus and Nicolaus Steno were describing and defining key concepts vital to developing an understanding of the natural world.
    1. Aristotle (384-322 BCE)
      1.  the Scala Naturae"Great Chain of Being" (Fig. 2.2)
    2. Carolus Linnaeus (1707-1778) [Fig. 2.3]
      1. Father of modern taxonomy
      2. The nested nature of biological classification (Fig. 2.4)
      3. taxonomy
        1. Linnaean System
           hierarchal system: hierarchy of taxonomic ranks.
    3. Nicholas Steno (1638-1686)
      1. Father of stratigraphy
      2. Fossils are remaims of once living organisms. Illustration from Steno's 1667 paper comparing the teeth of a shark head with a fossil tooth [Fig. 2.5].  Image to right from Wikipedia

  1. Natural Theology (p. 32)
    • the concept that adaptation of species to their environment was the result of god's design
    1. Nicholas Steno (1638-1686)
      1. Father of stratigraphy
      2. Fossils are remaims of once living organisms. Illustration from Steno's 1667 paper comparing the teeth of a shark head with a fossil tooth [Fig. 2.5].  Image to right from Wikipedia
    2. Robert Hooke (Fig 2.6)
    3. William Paley
  2. 2.2 - Evolution Before Darwin (p. 34)
    • The concept that life changes over the course of vast stretches of time was being vigorously debated before Darwin was born.
  3. Fossils and Extinctions (p. 34)
    • Paleontology thrived as scientists discovered evidence of incredible animals
    1. Georges Buffon (1707-1788) [Fig. 2.7]
      1. Earth formed according to laws of physics and chemistry
        1. Older than previously thought
      2. Life emerged as distinct types
        1. proposed that new varieties of species [but not species themselves] could arise in response to new habitats
        2. Transformed when environment changed
    2. Plenitude: As many organisms that could exist would exist. A beneficent god would not allow extinction.
    3. Leopold Chretien Frederic Dagobert [pseudonym 'Georges'],Baron Cuvier (1769-1832)
      1. Fossils demonstrated he Fact of Extinction (Fig. 2.8)
    4. James Hutton (1726-1797) and Charles Lyell (1797-1875)
      1. Uniformitarianism
        1. Observable processes produce small changes that accumulate over time
        2. The earth must be immensely old: "No vestige of a beginning, no prospect of an end"
    5. William Smith (1769-1839) [fig 2.10]
      1. The principle of faunal succession
        1. Different rock layers contain distinct fossils
        2. Fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances 
        3. Geological Map of England and Wales - 1815 [fig 2.11]
  4. Evolution as Striving
    1. Jean-Baptiste Larmarck [Fig. 2.13]
      1. Jean-Baptiste Lamarck proposed one of the first theories of evolution based on natural laws: that animals and plants strived for existence
      2. Evolution is a process that follows natural laws
      3. Life driven from simple to complex
        1. Complex species descended from microbes
        2. Microbes continually generated spontaneously
      4. Inheritence of Acquired Characteristics (Box 2.1)


Figure 2.2 Scala Naturae from the Liber de ascensu et decensu intellectus of Ramon Llull (written 1304, first published 1512)


Fig. 2.3 Carl von Linné, portrait by Alexander Roslin, 1775. Currently owned by and displayed at the Royal Swedish Academy of Sciences.


Illustration from Steno's 1667 paper comparing the teeth of a shark head with a fossil tooth. from Wikipedia

Smith's famous 1815 geological map

Smith's famous 1815 geological map

  1. 2.3 The Unofficial Naturalist (p. 39)
    1. Charles Darwin (1809-1882) [Figs. 2.1, 2.21]
      1. Charles Darwin developed as a naturalist while on his voyage, using pivotal concepts such as Charles Lyell’s uniformitarianism, to explain the distribution of fossils and organisms he encountered on his journey.
      2. The Voyage of the Beagle [1831-1835] (2.14)
        1. Galapagos
        2. Galapagos Islands
        3. tortoises, mockingbirds, and finches (Fig. 2.15, more in chapter 8)
      3. Relationships Among Species
        1. Similar species tend to be clustered geographically, suggesting descent from a common ancestor, not independent creation
          1. e.g., Galapagos Finches. (CHAPTER 8)
      4. Hypotheses and Theories in Science (Box 2.2)
      5. Lyell's influence
      6. Alfred Russel Wallace, Darwin, and natural selection
Longitudinal section of HMS Beagle as of 1832

Fig. 2.15Darwin's Finches

A page of hand-written notes, with a sketch of branching lines.
Fig. 2.16, from Wikipedia: In mid-July 1837 Darwin started his "B" notebook on Transmutation of Species, and on page 36 wrote "I think" above his first evolutionary tree.
  1. Common Descent p. 42
    1. As the discipline of taxonomy developed, so did scientists’ understanding of homologous traits (shared because of a common ancestor) and analogous traits (shared forms).
    2. homologous characters (Fig.2.17)

      1. character state inherited from common ancestor
      2. homology is determined by position relative to other structures; development  & evolution
      3. UCMP on homology and analogy
      4. embryological homology (pattern of ontogeny)
        1. Branchial arch circulation in fish and mammalian embryos (Fig. 2.18)
      5. Molecular homologies
        1. Universal genetic code (Fig 5.8)
        2. Shared flaws in genetic makeup
        3. Pseudogenes: e.g., globin family that do not code for proteins
          1.    Facts Of Evolution: Retroviruses And Pseudogenes from the Cassiopeia Project
  1. Natural Selection p. 44
    1. Darwin argued that the patterns observed in nature reflected a common inheritance, and that natural selection, just like selection by breeders, could lead to the diversity of species and fossils observed.
    2. artificial selection
DARWIN'S theory of evolution by natural selection consists of three inferences based on five facts (Fig. 2.19)
  1. Fact 1
    1. All species have an astonishing reproductive capacity (biotic potential)
      1. Thomas Malthus
  2. Fact 2
    1. in stable populations, each parent leaves on average of one offspring
  3. Fact 3
    1. Natural resources are limited
  4. Inference 1
    1. Often only a few individuals survive
  5. Inference 2
    1. Survival is not random
    2. individuals vary in their ability to survive and reproduce (natural selection)
  6. Fact 4
    1. Individuals within species vary
  7. Fact 5
    1. some of these variations are passed on to offspring
  8. Inference 3
    1. individuals with the most favorable adaptations are more likely to survive and reproduce.
    2. Over time natural selection will lead to the evolution of new species


  1. Individuals within populations vary
  2. Some of these variations are passed on to offspring
  3. In every generation some individuals are more successful in surviving or reproducing than others.
  4. Survival and reproduction are not random. Individuals with the most favorable variations are more likely to survive and reproduce.

2.4 Darwin in the Twenty-First Century (p. 45)

  1. In 1859, Darwin established many of the fundamental principles of evolution.

  2. However, evolutionary biology has developed far beyond his initial formulation in the years since.

    1. Sexual selection

      1. Selection for traits that provide a mating advantage

    1. Genetic drift

      1. Change in frequency of traits due to chance events


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