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History of Natural Theology. Classical Greek philosophers had ideas about the natural evolution of life Plato (427-347 B.C.) believed there were two worlds. A real world which was perfect and an illusionary world that was imperfect. He did not believe in evolution.
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History of Natural Theology • Classical Greek philosophers had ideas about the natural evolution of life • Plato (427-347 B.C.) believed there were two worlds. A real world which was perfect and an illusionary world that was imperfect. • He did not believe in evolution. • His student Aristotle (384 -322 B.C.) believed that all forms could be arranged on a ladder or scale called the “scala naturae” Each form of life had an allotted rung on the ladder. • Belief prevailed for 200 years.
Carolus Linnaeus(1707- 1778) • Father of taxonomy. • Taxonomy is the branch of biology concerned with naming and classifying organisms. • Came up with Kingdom, Phylum, Class, Order, Genus, Species. • However he believed there was no evolutionary kinship between them.
Georges Cuvier(1769-1832) • Paleontologist. • Documented and recorded the succession of fossils in sedimentary strata in the Paris Basin. • Found deeper and older fossils to be dissimilar. New species appear and older species disappear. • Advocated catastrophism. Species killed off by catastrophes and recreated.
James Hutton(1726-1797) • Scottish geologist. • Proposed gradualism . • Profound changes are due to gradual changes over a long period of time due to natural processes occurring within the Earth’s crust.
Charles Lyell (1797-1875) • Proposed uniformitarianism. The idea that geological processes have not changed over time and are at work. • Suggested the earth was a lot older than the previously thought 6000 years. • Processes persisting over long periods of time can accumulate to substantial change.
Jean Baptist Lamark • Was in charge of an invertebrate collection at the Natural History Museum in Paris. • Noticed that species changed over time. • Proposed that phenotype can change in response to environment changes and those new characteristics were passed on to the offspring. • First idea that adaptations occur in response to the environment.
The Darwinian Revolution • Charles Darwin(1809 -1882) was born in Shrewsbury, England. • Wanted to be naturalist but was sent to medical school in Edinborough at 16. • He dropped out and went to Christ College at Cambridge University and became a clergyman. Back then most naturalist were clergyman. • Viewed the world as natural theologists. • The view that each species was newly designed and non-evolving.
Reverend Robert Henslow • Botany professor at Cambridge. • Darwin was his protégé • At age 22 he was recommended to join Captain Robert Fitzroy on the H.M.S. Beagle to sail around the world. • The primary mission was to chart the South American coastline. • Darwin collected and observed the flora and fauna.
Descent With Modification A Darwinian View of Life
The Galapagos • Species unique although they most closely resembled South American species. • Darwin’s finches possessed different beaks to accommodate different modes of eating. • Darwin read Principles of Geology by Lyell and surmised that “old Earth” was inhabited by evolving species.
The Origin of Species • Lyell and a collegue presented Darwin’s work Along with another British scientist by the name of Alfred Wallace. • The paper was on the theory of “Natural Selection” which Wallace and Darwin came up with simultaneously. • Darwin published “The Origin of Species” a year later.
Darwin’s Observations • Species had distinct South American characteristics. • South American species that lived in the temperate regions more closely resembled the tropical species on the same continent than species that resided in the temperate regions on a different continent. • South American fossils resembled south American species.
Observations That Lead Darwin to the Theory of Natural Selection • OBSERVATIONS • All species have the potential to reproduce the maximum number of offspring. • Populations remain stable (except for seasonal fulgurations. • Resources are limited • CONCLUSION • Organisms compete for food.
Other Observations • Organisms vary • Organism with suitable traits survive to reproduce. • Gradual changes in a population occur and the population accumulates favorable characteristics.
Additional Evidence for Natural Selection • Homology similarities in characteristics due to a common ancestor. • Anatomical homologies • similar structures, different function. • Embryological homologies • Similar structural development. • Molecular homologies • Basic machinery of RNA and DNA are similar. • Biogeographic homologies Convergent evolution
Homologies • Biogeographic homologies • Endemic species. • Convergent evolution - species that look similar but have no common ancestry. • Divergent evolution – species that have common ancestry but evolve disparate characteristics. • Fossil Record – the appearance of certain classes of vertebrates in the fossil record. • Fish before amphibians
Natural Selection • Differential success in reproduction. • Variation in populations and how they respond to the environment. • The product of adaptation to their environment.
