Charles Darwin

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Charles Darwin

• . . .a theory of descent with modification
  through variation and natural selection.

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The Expansion of Science

• Descartes' Mechanical world made science
  possible (although Descartes himself was not an
  empiricist)
• Carl von Linné (Linnaeus) published Philosophia
  Botanica (1752)
• The Age of Reason promoted the idea of Progress
  in science--more can be discovered. The
  Industrial Revolution begins.

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Scientific Research Posed Problems Question 1

• How do we account for fossils of species that
  appear to be extinct?
• In the Great Chain of Being, every species had a
  vital role to play in Gods vast ecological
  network. God would not make spare parts.

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Scientific Research Problems Question 1
Such is the economy of nature, that no instance
can be produced of her having permitted any one
race of animals to become extinct. Thomas
Jefferson, 1785

• John Wesley, the religious reformer, pronounced,
  in 1770, Death is never permitted to destroy
  even the most inconsiderable species.

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Scientific Research Posed Problems Question 2

• The fossils of some extinct species, e.g.,
  mammoths, giant sloths, horse-like creatures,
  seemed to resemble contemporary species. Were
  they related if so how?

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The Fossil RecordApparent Links
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The Fossil RecordIs this a Link?
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Scientific Research Posed Problems Question 3

• How do we account for the geographic distribution
  of animals in the world, e.g., marsupials and
  flightless birds in Australia, finches and
  turtles in the Galapagos Asian and African
  elephants?
• Did that all occur at the end of the trip on the
  biblical ark? How did the species spread in such
  exact patterns? Why are more closely related
  species usually found closer to each other (e.g.,
  hummingbirds in the Galapagos, drosophila in the
  Hawaiian islands).

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Scientific Research Posed Problems Question 4

• Why does there appear to be a progression of
  complexity of fossils found in different layers
  of the earths crust?
• Why are there no species or only simple species
  in the oldest layers, and why do vertebrates
  appear only in more recent layers? Why are
  species in closer layers more closely related?

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Scientific Research Posed Problems Question 5

• How do we account for the many evidences that
  the earth is many millions of years old?

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Scientific Research Posed Problems Question 6

• How do we reconcile the evidence that people have
  been living and dying for thousands of years with
  the Bible record?
• How do we reconcile evidence that animals have
  been living and dying steadily for millions of
  years with the biblical idea that death did not
  occur until after Adams fall.

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• How do we reconcile these strange new
  observations with biblical creation,the story of
  the fall, and the story of the flood?

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Early Answers
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Ralph Waldo Emerson on Evolution

• Ralph Waldo Emerson's fledgling evolutionary
  faith began to emerge in his 1834 lecture "The
  Relation of Man to the Globe. after reading Sir
  Charles Lyells Principles of Geology . . .
  "Man," Emerson said, "is no upstart in the
  creation, but has been prophesied in nature for a
  thousand thousand ages before he appeared." . .
  .
• From times incalculably remote" there had been
  a "progressive preparation" for the human
  species, carried out in the lower or "meaner
  creatures" preceding it. "Man," as Emerson told
  his audience, "was not made sooner, because his
  house was not ready."4

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Emerson (Contd)

• In this same lecture, Emerson chronicled the way
  in which the hard rock that once surfaced the
  earth gradually became covered with soils more
  hospitable to life. With this development the
  "first faint traces of vegetable and animal life
  begin to appear, and in the lowest strata the
  most imperfect forms zoophytes, shells, and
  crustaceous animals then fishes and reptiles."5
  When these rudimentary forms had existed for some
  time, "Then a new formation the remains of a
  new and higher order begin to appear, more
  nearly resembling man, and giving earnest of his
  approach and as the new race waxes, the old race
  retires."6

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Emerson (Contd)

• As a result of his scientific studies, Emerson
  concluded that one of the distinguishing
  characteristics of the "present age" was "the
  study of organic remains," and that "solid
  learning is got from the fossils." When we look
  at the geologic record, he reflected, there are
  "No leaps, no magic," but rather the "eternal
  tranquil procession of old familiar laws.1834
  (Gordon, Robert C., PhD)

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Cuviers Proposal

• The world has gone through a number of great
  catastrophes, with the flood being the last.
  After each catastrophe, God would repopulate the
  earth with a new creation and a batch of new
  species.

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A New Proposal

• Charles Darwin, in 1859, proposed a theory of
  descent with modification through variation and
  natural selection.

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Charles Darwin--Background

• It was intended that Charles, like his father and
  grandfather, would become a doctor. At Edinburgh,
  he could not bear to watch the surgeries, done
  without anesthesia, so he dropped out.
• Later, he finished his studies at Cambridge,
  where he studied for the ministry. However, at
  Cambridge he developed a passion for collecting
  biological specimens.

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Charles Darwin--The Journey

• His mentor at Cambridge, Henslow, recommended him
  to be ships naturalist on the HMS Beagle.
• Darwin embarked on Dec. 27, 1831, for what became
  a 5-year trip mapping the coastlines around South
  America and elsewhere.
• He took with him volume 1 of Sir Charles Lyells
  new book, Principles of Geology. This book argued
  that the world was millions of years old, with
  changes taking place slowly.

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Charles Darwin--After the Journey

• Darwins journals and specimens had assured him a
  good reputation before he had returned.
• He wrote the book on the formation of coral
  reefs.
• He did ground-breaking research on barnacles.

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Charles Darwin--The Theory

• Darwin, in 1838, read Robert Malthuss Essay on
  Population, an essay that argued that animals
  would have to struggle to survive since they
  would multiply faster than the food supply.
• For the first time, Darwin thought of a mechanism
  to explain how extinct species could be related
  to current species and how species could vary.
• Nature was not unlike a breeder of horses
  creatures with mutations that helped them get a
  meal (or escape being a meal) and a date were
  selected over others.

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Natural Selection at work
ltBird of Paradisegt
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Charles Darwin--The Theory

• In 1842, he wrote out a 35 page pencil sketch of
  his ideas.
• In 1844, he expanded it to 231 pages, put the
  manuscript in a safe with some money and
  instructions to publish it after he was dead.
• He wrote to Lyle, Hooker, Huxley and others,
  explaining his theory. He continued research on
  the theory of natural selection.

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Charles Darwin--The Theory

• In 1845, he wrote, In my wildest daydream, I
  never expect more than to show that there are two
  sides to the question of the immutability of
  species. (Irvine)
• During the next few years, he corresponded with
  Alfred Russell Wallace, a naturalist in Indonesia
  whose observations were leading him in the
  direction Darwin had gone. But Wallaces ideas
  were tentative and undeveloped.

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Darwin--The Impetus to Publish

• The bombshell came on June 18, 1858. Alfred
  Russel Wallace sent Darwin a long letter
  outlining his new theory of species emerging,
  reaching the same conclusions in an uncanny
  parallel to the way that Darwin had.

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Charles Darwin--The Theory

• In 1859, Darwin published On The Origin of
  Species.

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Darwins Three Premises

• Creatures produce more offspring than can
  survive.
• There is great variation within a species.
• Some of that variation is passed on to future
  generations.

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Darwins First Premise

• Creatures produce more offspring than can
  survive.
• From Robert Malthus, Darwin got the idea that
  the population of a species grows faster than the
  food supply therefore, there will be a
  competitive struggle for food. In the process of
  the struggle for food, those more fit will live.

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Darwins Second Premise

• There is great variation within a species.
• From his travels on the Beagle, on which he
  collected thousands of specimens, as well as in
  his observations of pigeons, dogs, other
  domesticated animals, and the human species,
  Darwin observed a huge variety within a species.
  Even within this class, we all vary.

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Darwins Third Premise

• Some of that variation is passed on to future
  generations.
• Although Darwin had not read Mendel, he knew, as
  we do, that some of the variation that randomly
  occurs within a species is passed on. For
  example, people born with an extra finger
  (polydactyly) often had descendants with extra
  digits. Sheep with thicker wool were bred
  (artificially selected) to produce offspring with
  thicker wool. Cows giving more milk are bred to
  produce offspring who also give more milk.

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Darwins Conclusion-- 1Natural Selection

• In a natural setting, through natural selection,
  any variation (i. e. mutation) that helps an
  organism adapt to the environment, i.e., get
  food, escape predators, and find a mate, is most
  likely to be passed on.

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Darwins Conclusion-- 2Varieties could become
new Species

• Given the geologic age of the earth outlined by
  Lyle, the variation occurring within a species
  could become so great that varieties would become
  new species.
• Given enough time, all species could have evolved
  from one prototype.

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Evolution -- Fact or Theory?

• Since descent with modification, Darwins idea
  of evolution, is a fact, what is the big
  controversy over Darwins theory?
• Dogs, which come from one common ancestor, have
  evolved into great varieties.
• Cows give more milk, pigs have less fat, tomatoes
  are larger, sheep have more wool, turkeys have
  more white meat--many things have evolved.

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Darwins Controversy 1Natural Selection

• The controversy hinges on two main points. First,
  while the variety among dogs, cows, etc., is
  created by artificial selection, Darwin argued
  that competition in nature would cause the same
  kind of variety by natural selection, without
  divine direction.

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Darwins Controversy 2New species could evolve
from varieties

• Second, given the great age of the earth proposed
  by Sir Charles Lyle, variations within a species
  could cross the genetic line and become separate
  species.
• In fact, concludes Darwin, all species might be
  developed from one original prototype without
  divine intervention.

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• Darwin was impressed by the extreme difficulty,
  or rather impossibility, of conceiving the
  immense and wonderful universe, including man . .
  . As the result of blind chance or necessity.
  When thus reflecting, I feel compelled to look to
  a First Cause having an intelligent mind in some
  degree analogous to that of man, and I deserve to
  be called a Theist. . . . But then arises the
  doubt, can the mind of man, which has, as I fully
  believe, been developed from a mind as low as
  that possessed by the lowest animal, be trusted
  when it draws such grand conclusions.? (Qtd. in
  Midgley, Mary. Purpose, Meaning and Darwinism.
  Philosophy Now Jan./Feb. 2009 16-19.)

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Summary

• Darwin did not introduce the idea of evolution
  rather, he proposed the theory of Natural
  Selection.
• Darwin did not claim that humans came from
  monkeys rather, he theorized that all species
  may have come from earlier prototypes, perhaps
  from one single prototype.
• His theory has profoundly affected the way we
  think about science and nature.
• For over a century, his basic claims have been
  largely supported by scientific studies.

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Herbert SpencerThe Application of Evolutionary
Thought to Society in Social Darwinism

• Spencer was a prominent Victorian scientist whose
  aim was to bring fields such as psychology and
  sociology within the same framework and rigor as
  the natural and biological sciences.
• His social theories became known as Social
  Darwinism and were applied to capitalism,
  communism, and the nationalism that was the
  beginnings of the Nazi movement.

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Herbert SpencerThe Application of Evolutionary
Thought to Society

• Capitalism and Social Darwinism
• Capitalists such as Andrew Carnegie and John D.
  Rockefeller argued that capitalism was the best
  form of survival of the fittest.
• They argued that the government should not help
  the poor, infirm, or unfit. If the lower classes
  died in their factories of mills, that was just a
  natural process by which society was improved.
  Rockefeller called it a Law of God and of
  Nature.

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Herbert SpencerThe Application of Evolutionary
Thought to Society

• Communism and Social Darwinism
• Karl Marx saw in Social Darwinism the idea that
  we could alter the environment of individuals and
  thereby develop new traits and qualities. For
  example, the abolition of private property could
  lead to humans getting rid of their aggressions,
  leading to a Utopian society.

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Herbert SpencerThe Application of Evolutionary
Thought to Society

• Nazism and Social Darwinism
• Early German nationalists argued that nations
  were essentially the same as members of a
  species. When fighting between nations occurred,
  the human race was made fitter. They also
  argued that it was a natural process to eliminate
  inferior nations or peoples.