Biological Evolution I Fossil Photos: R. Weller, Cochise College
Before we proceed . . . • Evolution is not a belief system. It is a scientific concept. It has no role in defining religion or religious beliefs. • Evolution is a theory, but you do not get any better than that in science. • There is some contention about evolution, but not among scientists or scientific organizations concerning its basic validity.
Evolution • Evolution is change over time. • Biological Evolution: change in a population’s genetic structure (gene frequency) over time. • Evolution explains how life has changed over 3.7 billion years. • Critically important integrating concept of biology that explains the similarity and diversity of life. • Major mechanism worked out by Charles Darwin.
• Explains similarity, diversity, and relatedness of life. • Explains development of resistance to antibiotics and pesticides. And why we must get a new flu shot each year. • Evolution is far more than only a theoretical consideration. Understanding evolution saves lives. Evolution is the keystone of biology Evolution
Four Historical Obstacles to Developing an Evolutionary Concept in Biology 1.) Belief in a young Earth. Bishop Ussher calculated age of Earth from Old Testament genealogies. He said Earth was created: 4004 BC Sunday October 23 9:00 am Too much detail?
Obstacles (cont’d.) 2. Belief in fixity of species. The idea that a deity created species, and they do not change. Associated with the Great Chain of Being or scala naturae of Aristotle. Scala Naturae Christians later modified to add angels and God to Aristotle’s original hierarchical concept.
Obstacles (cont’d.) 3. Rigid religious views. Unholy combination of religion and political power (divine right).
Obstacles (cont’d.) 4. Lack of biological knowledge. There was a lack of understanding about the way the world worked, which limited advancement of an evolutionary concept.
In 1800’s Lamarck proposed evolution occurred by inheritance of acquired characteristics. Belief that phenotypic features acquired in life through use and dis-use are “absorbed” into the genotype and passed to offspring. Driven by “inner need,” and use and dis-use. Lamarckian experiment: cut off tails of mice and expect their offspring to be born without tails. Lysenko, Agriculture Secretary of former USSR, advocated Lamarckian ideas, put Soviet ag behind, USA used wheat sales to USSR as a negotiating tool for nuclear disarmament. Lysenkoism =pseudoscience Jean-Baptiste Lamarck’s Mechanism of Evolution Trofim Lysenko
Lamarck's theory: variation is acquired. stretching stretching reproduction
Phenotypes do not typically change in a manner that makes the changes heritable.
Malthus’ “Essay on Principles of Population” • Thomas Malthus' (1766-1834) essay on population growth helped inspire Darwin to develop the theory of natural selection.
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