Lecture #3—Introducing Mr. Darwin
This lecture does 2 things.
1) It outlined the historical development of science in the Western World. Over a few hundred years we went from a world where we explained the physical world in terms of gods performing miracles to explaining it in terms of principles of science—chemistry, physics, geology, and biology.
This occurred because a) the dominant religion (Roman Catholicism) lost influence during the Protestant Reformation; the church was no longer the accepted authority on all things. b) Science and its rule that we should test our ideas and use evidence became the new way of explaining things as instruments were invented (e.g. microscope, telescope) and voyages of discovery revealed new ways of thinking. We became less dependent upon miracles and the supernatural for explanations of lightening, thunder, volcanoes, and earthquakes and more dependent upon science to provide the answers.
2) The lecture shows how biology changed over this period. How our organs (e.g. heart, brain) functioned began to be explained in terms of physics and chemistry not mysterious humors. We began to use science to explain 4 fundamental questions about life: life’s origin, the diversity and adaptations of organisms, and the ladder of life (Scala Naturae), the hierarchy which explained our station (fixed position) in the world order.
The Devine Creation Hypothesis (the prevalent view of the Catholic Church and described in the Bible) explained that God did it all by miracle.
The Evolution Hypothesis challenged and displaced the Creation model beginning in the 1800’s when the Frenchman Jean Baptiste Lamarck (1809) and Charles Darwin ( 1859) proposed mechanisms how organisms could change through time. Lamarck proposed that organisms adapt by passing on characteristics they had acquired in their life to their offspring (Acquired Characteristics by use and disuse). Darwin and Alfred Wallace provided overwhelming evidence that evolution had occurred and that natural selection was a mechanism of evolution.
Darwin’s 5 year trip around the world trip on the ship the HMS Beagle gave him 3 clues that evolution had occurred. 1) He observed great variation within single species (this suggested that species were not fixed forever in their body form). 2) He discovered giant armadillo fossils where small living armadillos lived (this suggested that the giants might have been the ancestors). 3) He visited the Galapagos Islands and found that each island had slightly different species of tortoises, birds, plants, and reptiles similar to those on the mainland of South America (this suggested that these species had gotten to the islands long ago by storms and had specialized into different species). All of this suggested evolution had occurred.
Darwin and Wallace both came up with the idea of natural selection by reading a book by the reverend Thomas Malthus who stressed that humans could rapidly run out of food and resources because their reproductive rate far exceeded the ability of the world’s resources to keep them alive. War, disease, and starvation keep the human population in check. Darwin and Wallace said similar forces would keep the organisms of the world from overbreeding. The competition among them would mean that only the best examples of the species would survive and that only they could pass their traits to their offspring. So that the next generation would be better at survival and would be different (survival of the fittest) thus the species would change through time.
The details of this process will occupy us in the next lectures
Define these Terms/ Concepts
Devine Creation Hypothesis
Evolution Hypothesis
Acquired Characteristics
Natural Selection
Charles Darwin
Alfred Russel Wallace
Thomas Malthus
Jean Baptiste Lamarck
Scala Naturae
Can you answer the following questions?
1) How do Lamarck’s and Darwin’s mechanisms of evolution differ?
2) What was the Protestant Reformation and what influence did it have on the development of scientific thinking?
3) What was the Scala Naturae model of how the world is organized and why did inhibit any concept of evolution from being accepted?
4) What were the three clues that made Darwin begin to change his views about the Devine Creation view of the world?
5) Compare and contrast the Devine Creation and Evolution Models of the biological world.