The Frailty of the Darwinian Hypothesis, Part 1
Editor’s Note: Ann Gauger is a senior research scientist at Biologic Institute. Her work uses molecular genetics and genomic engineering to study the origin, organization and operation of metabolic pathways. She received a BS in biology from MIT, and a PhD in developmental biology from the University of Washington, where she studied cell adhesion molecules involved in Drosophila embryogenesis. As a post-doctoral fellow in the Department of Molecular and Cellular Biology at Harvard, she cloned and characterized the Drosophila kinesin light chain. Her research has been published in Nature, Development, and the Journal of Biological Chemistry. Her awards include a National Science Foundation pre-doctoral fellowship and an American Cancer Society post-doctoral fellowship.
A long-standing controversy exists among evolutionary biologists that is little known outside of professional journals. This controversy is significant because it deals directly with the question of how evolutionary processes produce functional changes in organisms — whether or not the changes we observe are due to adaptive processes guided by natural selection.
Why such a controversy? In his landmark book On the Origin of Species, Darwin proposed natural selection as a force sufficient to account for the organismal complexity and diversity we see around us today. But Darwin knew nothing about genetics or molecular biology. He knew nothing about how variation among organisms was produced or inherited, or what the limits of variation might be. He knew nothing about population dynamics or how difficult it might be for a slightly advantageous trait to spread throughout a population.
In the many years since Darwin wrote his book, scientists have learned much about these topics, and as a result, they have identified four forces driving evolution, not just the one known to Darwin. The four forces are natural selection, mutation, recombination, and genetic drift, and when taken together they affect evolving populations of organisms in sometimes surprising ways. This has led to the controversy I outlined above concerning the efficacy of natural selection to drive evolution in adaptive directions.
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