Chapter 2: Evolution: Constructing a Fundamental Scientific Theory
Chapter Summary
Focus of the chapter:
- History of the theory of evolution.
- Darwin's contribution to evolutionary theory.
- The modern developments in evolutionary theory.
The term natural selection was developed by Charles Darwin to describe his ideas that biological traits which enhanced an organism's survival in an environment would increase in frequency over time.
Darwin was influenced by ideas or concepts from different fields, including the idea of uniformitarianism or the idea that the natural processes affecting the earth are the same as in the past.
Evolution by natural selection can be contrasted with Lamark's idea of inheritance of acquired characteristics; the idea that traits gained by organisms during their life are passed on to their offspring at reproduction.
Modern evolutionary theory combines Darwin's natural selection with three other mechanisms of evolution: mutation, gene flow, and genetic drift. Mutation is the only way new genetic material makes its way into the gene pool. Gene flow refers to the spread of new genetic material from one population to another while genetic drift is the random change in gene frequency.
Charles Darwin was not aware of the plant experiments conducted by Gregor Mendel; experiments which led to the modern day field of genetics. The 1953 description of DNA, the blueprint to life, profoundly affected the understanding of the way the mechanisms of evolution occur.
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