Executive Committee Statement on Evolution (January 2007)
(modified from the Department of Zoology statement)
Biological evolution, defined as genetic changes in species over time, is easily observed in the world around us; for example insects evolve resistance to pesticides and new diseases arise when viruses evolve the ability to invade new hosts. The theory of evolution explains the mechanisms (e.g. non-random natural selection acting on random mutation) by which organisms change over time, become more complex, and diversify into new species.
In popular speech, the word 'theory' means 'a guess', or ‘hypothesis’. However, in science, 'theory' refers to an explanation supported by facts. A well-tested hypothesis rises to the level of theory when it has been tested repeatedly without being falsified. Thus, a theory is as close to the truth as science can come. This is because scientific theories are rigorously subjected to the test of new knowledge, often gained by advances in technology that were unavailable when the explanation was first proposed. Hence, even the most successful theories are, by definition, never proven, although any scientific theory can be refuted by facts that are at odds with its predictions. It is this quality that most distinguishes a scientific concept from a non-scientific one. Because science relies only on explanations that have the property that they can be falsified by testing, other kinds of explanations are beyond the scope of science because they cannot be falsified by empirical data.
Evolutionary theory is the central unifying theory of biology, supported by independent evidence from paleontology, geology, genetics, molecular biology and genomics, developmental biology, biogeography and behavioral ecology. Even though new information from nearly every field of science has been applied, attempts to falsify evolutionary theory using the scientific method have failed. As is true for any active science, the details of the theory are continually debated as new data are collected. However, there is overwhelming support among the scientific community about the fact of evolution, namely that organisms are observed to change genetically over time and can evolve into new species.
We oppose any attempt to weaken scientific standards with respect to evolution, to redefine the scientific process so as to exclude the requirement that explanations be falsifiable, or to broaden the science curriculum to include non-scientific explanations. In an expanding global economy that is increasingly driven by science and technology, it is essential that our children receive a first-class science education. In this, we stand with our colleagues in the National Academy of Sciences, the American Association for the Advancement of Science, and other scientific organizations.