Evolutionary Theory

 Evolution  What is your reaction to this term?  Biological sciences  Humans and Apes shared last common ancestor 5-8 million years ago.

 Discoveries came over a long time from a lot of sources  Charles Darwin  Alfred Russel Wallace  Middle Ages  Thought processes were static  Greek influence – Aristotle  Scientific Revolution  Europe vs. Arabia and India

 John Ray ( )  Coined terms species and genus  Carolus Linnaeus ( )  Fixity of species  George-Louis Le Clerc de Buffon ( )  Change does occur in the universe  Erasmus Darwin ( )  Charles Darwin’s Grandfather  Jean-Baptiste Lamarck ( )  First to propose evolutionary process

 Georges Cuvier ( )  Opponent of Lamarck  Charles Lyell ( )  Wrote Principles of Geology  Thomas Malthus ( )  English clergyman and economist  Mary Anning ( )  Discovered a lot of fossils

 John Baptiste Lamack was the first scientist to produce an explanation for the evolutionary process.  He believed that species change was influenced by environmental change.

 Georges Cuvier introduced the concept of extinction and the theory of catastrophism.  The view that the earth’s geological landscape is the result of violent cataclysmic events.  Cuvier promoted this view, especially in opposition to Lamarck.

 Thomas Malthus wrote about the relationship between food supply and population increase.  His essay on the Principle of Population led both Darwin and Wallace to the principle of natural selection.

 Charles Lyell developed the theory of uniformitarianism.

 Discovered the first complete fossil of Ichthyosaurus, a large fishlike marine reptile.  She became known as one of the world’s leading “fossilists” and contributed to the understanding of the evolution of marine life over 200 million years ago.

 Ideas were formed while serving as a naturalist on the voyage of the HMS beagle.  Darwin saw the importance of biological variation within a species.  Recognized the importance of sexual reproduction in increasing variation.  By 1844, Darwin had complete the work that he would publish fifteen years later.

 A naturalist who worked in South America and Southeast Asia.  Suggested species descended from other species and new species were influenced by environmental factors.  Presented paper on evolution and natural selection to the Linnean Society of London jointly with Darwin.

 Charles Darwin ( )  Discovered first credible mechanism for evolutionary change  HMS Beagle  Finches and barnacles  Alfred Russel Wallace ( )  Developed own theory of natural selection  Wrote letter to Darwin

 Darwin’s formulation included:  Potential for reproductive rates that outpace the rate of food supply  The presence of biological variation within all species  Constant competition among individuals for survival  Favorable traits = increase in reproduction  Environment determines favorable traits  Favorable traits passed to offspring  Over long periods of time, successful variations accumulate in populations  Geographical isolation may result in new species

 Peppered moth in the UK  Galapagos birds and beak thickness

 The variation exhibited by dog breeds has been achieved in a relatively short time through artificial selection.

1. A trait must be inherited if natural selection is to act on it. 2. Natural selection can’t occur without population variation in inherited characteristics. 3. Fitness is a relative measure that changes as the environment changes. 4. Natural selection can only act on traits that affect reproduction.

 No one knew source of variation that Darwin explained  Did not know how favorable traits were passed down.  Laws of heredity unknown – Mendel had not come on the scene  DNA was not discovered until 1953

 Offensive to Christians because in conflict with Biblical versions of creation  Evolution considered to be a fact by most scientists today  Accepted in part by Catholic Church and most Protestants  Fundamentalists reject evolution Creationism Intelligent Design  Debate topic:  Should evolution be taught in public schools? If so should Creationism also be taught?