Focus of this chapter:
- History of the theory of evolution
- Darwin’s contribution to evolutionary theory
- The modern developments in evolutionary theory
Charles Darwin developed the term natural selection to describe his hypothesis that biological traits that enhanced an organism’s survival in an environment would increase in frequency over time.
Darwin was influenced by ideas and concepts from different fields, including uniformitarianism, the idea that the natural processes affecting the earth are the same as in the past.
Evolution by natural selection stands in contrast to Lamarck’s idea of inheritance of acquired characteristics, which stated that traits gained by organisms during their lives 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. Genetic drift is the random change in gene frequency.
Charles Darwin was not aware of the plant experiments conducted by Gregor Mendel, which led to the modern field of genetics. The 1953 description of DNA, the blueprint of life, profoundly affected our understanding of the way the mechanisms of evolution occur.