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Philosophy 024: Big Ideas Prof. Robert DiSalle ([email protected]) Talbot College 408, 519-661-2111 x85763 Office Hours: Monday and Wednesday 11:30-12:30 Course Website: http://instruct.uwo.ca/philosophy/024/ What is a theory of evolution? Species of animals and plants were not simply created in their present forms. Instead, their present forms are the results of gradual modifications in previous forms, representing adaptations to changing environments. Not only do individual species gradually change, but also new species come into being from previously-existing ones. Widely differing species can therefore have common origins in the distant past. The variety of existing species stems from a few simple forms. Charles Lyell (1797-1875) Principles of Geology (1830) Elements of Geology (1838) The Geological Evidence of the Antiquity of Man (1863) Gradualism: The formation of the earth’s geological structures has taken place by slow and gradual processes, identical to those that can now be observed-- e.g., erosion. This implies that the Earth has to be much older than contemporary Christians assumed it to be. Georges Cuvier (1769-1832) Discourse on the revolutionary upheavals on the surface of the globe, and on the changes they have produced in the animal kingdom (1825) Fossil remains indicate that earlier forms of animals have become extinct: dinosaurs, mammoths, etc. These extinctions result from extraordinary catastrophes in the otherwise uniform history of the globe. Jean-Baptiste Lamarck (1744-1829) Zoological Philosophy (1809) Natural History of Invertebrate Animals (1815) “Lamarckian” evolution: Species evolve by adapting to their environments. “First Law”: The use or disuse of physical structures by animals causes those structures to develop or to atrophy. “Second Law”: These structural changes are heritable. Adaptation: Individual animals change their own forms by use and disuse, in response to environmental conditions. Their offspring inherit these changes. Bishop James Usher (15811656) Annals of the Old and New Testament (1650) Careful study of the chronology of the Bible, based on the genealogies, allows us to calculate the amount of time since the creation of Adam, and so give a date for creation: October 26, 4004 BCE, 9:00 AM. Charles Darwin (1809-1882) The Voyage of the Beagle (1845) On the Origin of Species By Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life (1859) The Descent of Man, and Selection in Relation to Sex (1871) The Expression of the Emotions in Man and Animals (1872) The Darwinian theory: Evolution by natural selection (Blind variation and selective retention) 1. Inherited structural features of all living things are subject to random variation. 2. Some variations will be more useful than others for survival in a given environment, and will increase an organism’s chance of surviving and reproducing. 3. Any environment will have limited resources to support living populations, while organisms will tend to reproduce beyond what those resources will support. 4. There must be a struggle for existence which will “select” variations for survival and inheritance. Observations supporting Darwin’s view: 1. Geological patterns reveal the earth to be much older than previously thought, old enough for gradual processes (like natural selection) to have tremendous effects. 2. Fossil record indicates that numerous variations have existed and become extinct, and that many present species have ancestral forms. 3. Artificial selection in domesticated species reveals the same basic processes at work. 4. Different animal and plant species arise from very slight variations on a few basic structures. 5. Differentiation reflects differences in environmental pressures, among forms that are isolated from one another. The “descent of man” The ancestry of the primates: Our nearest relations, in their current natural state… …and after they take over… “Beware the beast Man, for he is the Devil's pawn. Alone among God's primates, he kills for sport or lust or greed. Yea, he will murder his brother to possess his brother's land. Let him not breed in great numbers, for he will make a desert of his home and yours. Shun him, for he is the harbinger of death.” (from the Sacred Scrolls of the Apes, 29:6) Ape sign language vocabulary Objects: • Apple • Banana • Orange • Drink • Eye • Nose • Ear • Hat • Baby • Verbs etc. • Hurt • Can’t • Finished • Hurry • Smart • Smell • Hear • Where • Chase Major works of sociobiology: Alled, Emerson, Park, Park, & Schmidt: Principles of Animal Ecology. (1949) W.D. Hamilton: “The genetical theory of social behavior,” Journal of Theoretical Biology, 7, 1-52. E.O. Wilson: Sociobiology: The new synthesis (1975) Against sociobiology: R.C. Lewontin, S. Rose, L. Kamin: Not In Our Genes (1985) Sociobiology: The theory that all human social structures and interactions are explainable from an evolutionary point of view Questions: Are social structures not merely influenced by evolutionary biology, but also determined? If human moral, intellectual, and social behavior is all continuous with that of animal species, how can we maintain the uniqueness of our species? If human behavior is genetically determined, what possibilities are there for the improvement of social relations and social structures? Can this view of human beings be reconciled with any traditional philosophical or religious views? Are we free?