 The Evolution of the Theory of Evolution
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 Podcast
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Intro
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Today, the 12th of February, 2008, is the 199th anniversary of the birth of Charles Darwin. Since this has been dubbed "Darwin Day," and all sorts of events are planned for the upcoming year commemorating Darwin's turning the "big 200" as well as the 150th anniversary of the publication of "The Origin of Species" in 2009, I thought it'd be a good time to discuss how evolution has been seen over the centuries, and what Darwin's unique contributions really were.
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This episode will approach the development of evolutionary theory as being essentially similar to a family tree -- with dead ends, odd side-branches, weird uncles, and all...
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This will have to be a very simplified treatment of the topic -- could do multiple episodes on each of the dozen or so individuals I'll mention in the course of this discussion. Might want to go to this episode's blog post on the SOS web site, follow along with the show notes to keep everybody straight.
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What is evolution?
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Some of the confusion about evolution comes from the fact that the word has left the scientific arena, and is being used in a number of senses in common culture (as is the case in the title of this episode).
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Evolution -- change in heritable traits of a population over successive generations. When evolution was originally proposed (and for hundreds of years later), genes and genetics were as yet undiscovered, and no certain mechanism for evolution existed. What Darwin did (in 1859) was to propose a mechanism for evolution; not the first evolutionary theory, has been tweaked many times since.
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Early conceptual history
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Concepts to track
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Whether / how changes in the natural world occur (hope you listened to episode 17!)
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What a "species" is, whether / how species change over time
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How changes are passed down
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The nature and importance of fossils
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People complain about current day intrusions of religion & politics into science -- but they show up throughout this story as well. In some places, Darwin's story presented in black / white fashion -- good scientist vs. bad clergy, but not that simple.
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As with many advances in science, a number of concepts had to be brought together in one place at one time -- Darwin's story is no exception.
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Genetics really starts with ancient animal husbandry -- essentially are "forcing" evolution via controlled breeding of tamed animals.
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A simple form of of biological evolution was supported in Classical times by Greek and Roman philosophers, in particular Anaximander, Xenophanes, and Lucretius (Titus Lucretius Carus). Mentioned fossils in their writings, may have been what motivated them. Unfortunately, it also meant that they thought species did not change over time, but new & different creatures were emerging from the Earth over time (but not recently). A number of classical schools of philosophy held that fossils were formed by the Earth, were generated essentially as copies of living things that passed by; others, that species emerged from the ground spontaneously and fossils were remains of creatures that didn't quite make it out.
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Aristotle flirted with a form of natural selection, that biological features were generated randomly with the useful ones surviving -- but these comments were ignored in the face of a greater body of his work discussing final causation. Basically, Aristotle thought that species were immutable once formed, and this held sway for centuries.
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Subsequently with the dominance of Christianity & reinforced by the Reformation came belief in a literal interpretation of the biblical story of creation according to Genesis, with the doctrine that God had directly "Created kinds" of organisms which were subsequently immutable.
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In 17th century English, the word evolution (from the Latin word "evolutio", meaning "unroll like a scroll") began to be used to refer to an orderly sequence of events, particularly one in which the outcome was somehow contained within it from the start.
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1665 -- Robert Hooke published Micrographia, an illustrated descriptions of his observations with a microscope. Included in this was his comparison of petrified wood to ordinary wood. Concluded that petrified wood was ordinary wood that had been soaked with "water impregnated with stony and earthy particles." Argued against the view that fossils were created by the Earth itself.
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1667 -- Nicholas Steno wrote a paper, comparing the teeth from a shark's head he had dissected to fossil objects commonly known as "tongue stones." Based on their similarities, concluded that the tongue stones must be fossilized shark teeth. Later works expanded on this, but since Steno (like most of his contemporaries) believed that the Earth was only a few thousand years old, he used the Biblical flood to explain marine fossils found far from the sea.
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 Erasmus Darwin (1731 - 1802)
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Buffon (1707 - 1788)
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Jean-Baptiste Lamarck (1744 - 1829)
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Georges Cuvier (1769 - 1832)
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James Hutton (1726 - 1797)
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Quick overview -- intellectual setting of the 19th century
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Thomas Malthus (1766 - 1834)
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Charles Lyell (1797 - 1875)
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Charles Darwin (1809 - 1882) & Alfred Wallace (1823 - 1913)
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End of the story? Not even vaguely...
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Gregor Mendel (1822 - 1884)
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Modern Evolutionary Synthesis (a.k.a., neo-Darwinism) -- merger of Darwin's ideas with genetics
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1928 -- Frederick Griffith showed that bacteria could transfer genetic information
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1943 -- Demonstration that DNA is the genetic material involved in Griffith's experiment
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1953 -- Franklin, Crick, and Watson decypher the double-helix form of DNA. Explains much about how it works within chromosomes, etc.
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Later side-branches (corruptions / misuses of evolutionary theory)
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Some are examples of individuals attempting to wrap their theories in Darwinian terms, as sort of a way of giving pet theories a patina of truth. In other cases, people opposed to Darwin's ideas attempt to link them to some abhorrent behavior as an attempt to discredit Darwin.
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Herbert Spencer (1820 - 1903) -- social "Darwinism"
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Francis Galton (1822 - 1911) -- eugenics
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Paul Kammerer (1880 - 1926) & neo-Lamarckianism
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Trofim Denisovich Lysenko (1898 - 1976) & Soviet "genetics"
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"Intelligent Design" advocates & guilt by association -- try to tie Darwin to a number of ideas
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Marxism
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Eugenics
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Social "Darwinism"
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Nazis & the holocaust
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Wrapup
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Theory of evolution is like a big puzzle, need to find all the pieces before you can put it together
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Historically, individuals only have some of the puzzle pieces. Took time for people to gather all the pieces, put them together in the right way.
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Even when all the science & data is right in front of you, sometimes tough to sort out the science from cultural and political influences -- same in the past as now.
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Darwin wasn't the first to think of evolution of species, or to think of natural selection. He was, though, the first to put them together, and to buttress them with the data and analysis necessary to make them more than just a big mental exercise.
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Sources and other links
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Individuals
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Concepts
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Misuse of concepts
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