University of Central Oklahoma Department of Biology *
Science is the disciplined, logical search for knowledge about all aspects of the universe. It is based on the observation of natural phenomena and seeks to explain these natural phenomena through hypothesis testing and experimentation. A scientific hypothesis is a proposed explanation of a natural event. This hypothesis must be, above all else, testable and falsifiable. If an explanation does not meet these two requirements, it is not a scientific hypothesis. A scientific theory, in comparison to a hypothesis, is broader in scope and composed of a set of hypotheses that have been thoroughly tested. The term theory in the general public is synonymous with a guess. This is not so for a scientific theory. A scientific theory is supported by a large body of evidence and is continually tested and refined through the generation of new hypotheses. This is true for the theory of evolution.
Evolution is defined simply as the change in allele frequencies (genetic makeup) in a population through time. These changes can be small in scale, resulting for example in a population of bacteria becoming resistant to antibiotics, or large in scale, giving rise to a new species through a speciation event. The theory of evolution explains the mechanisms that lead to these changes. These mechanisms include non-random natural selection, random mutation events, random genetic drift, and gene flow. Each of these mechanisms has been and continues to be subjected to hypothesis testing. The theory is modified as new information is acquired through these tests; however, the overall theory of evolution continues to be upheld. Support for this theory comes from a variety of disciplines (e.g., paleontology, morphology, genetics, molecular biology, ecology, developmental biology, and biogeography). The theory of evolution is the unifying theory in biology and the fact of evolution is not controversial in the scientific community.