If there are any biology teachers out there who believe, as Discovery Institute does, that the “strengths and weaknesses” of Darwinian evolution should be taught in science classrooms, below is something you can distribute to your students without fear of losing your job. If you want to play it safe, I suggest you distribute the original.
On the other hand, if you don’t mind being a test case for academic freedom, just label this as a news item “Ideas on Evolution Going Through a Revolution among Scientists” that you copied from the Discovery Institute blog, and pull out the original after the school board has started proceedings aganst you.
Biology’s understanding of how evolution works, which has long postulated a gradual process of Darwinian natural selection acting on genetic mutations, is undergoing its broadest and deepest revolution in nearly 50 years.
At the heart of the revolution is something that might seem a paradox. Recent discoveries have only strengthened Darwin’s epochal conclusion that all forms of life evolved from a common ancestor. Genetic analysis, for example, has shown that every organism is governed by the same genetic code controlling the same biochemical processes. At the same time, however, many studies suggest that the origin of species was not the way Darwin suggested or even the way most evolutionists thought after the 1930s and 1940s, when Darwin’s ideas were fused with the rediscovered genetics of Gregor Mendel.
Exactly how evolution happened is now a matter of great controversy among biologists. Although the debate has been under way for several years, it reached a crescendo last month, as some 150 scientists specializing in evolutionary studies met for four days in Chicago’s Field Museum of Natural History to thrash out a variety of new hypotheses that are challenging older ideas.
The meeting, which was closed to all but a few observers, included nearly all the leading evolutionists in paleontology, population genetics, taxonomy and related fields.
No clear resolution of the controversies was in sight. This fact has often been exploited by religious fundamentalists who misunderstood it to suggest weakness in the fact of evolution rather than the perceived mechanism. Actually, it reflects significant progress toward a much deeper understanding of the history of life on Earth.
At issue during the Chicago meeting was macroevolution, a term that is itself a matter of debate but which generally refers to the evolution of major differences, such as those separating species or larger classifications. Most agree that macroevolution is, for example, what made crustaceans different from mollusks. It is the process by which birds and mammals evolved out of reptiles. It is also what gave rise to major evolutionary innovations shared by many groups, such as the flower in higher plants or the eye in vertebrates.
Darwin suggested that such major products of evolution were the results of very long periods of gradual natural selection, the mechanism that is widely accepted today as accounting for minor adaptations. These small variations, considered products of microevolution, account for such things as the different varieties of finches Darwin found in the Galapagos Islands. Under human control, or “artificial selection,” microevolution has produced all the varieties of domestic dog, all of which remain members of a single species.
Darwin, however, knew he was on shaky ground in extending natural selection to account for differences between major groups of organisms. The fossil record of his day showed no gradual transitions between such groups but he suggested that further fossil discoveries would fill the missing links.
“The pattern that we were told to find for the last 120 years does not exist,” declared Niles Eldridge, a paleontologist from the American Museum of Natural History in New York.
Eldridge reminded the meeting of what many fossil hunters have recognized as they trace the history of a species through successive layers of ancient sediments. Species simply appear at a given point in geologic time, persist largely unchanged for a few million years and then disappear. There are very few examples — some say none — of one species shading gradually into another.