Evolution makes testable predictions
By David Annis
Article ID: 1226
In the late 1850s, Charles Darwin and Alfred Russel Wallace introduced the world to the theory of evolution. The theory of evolution is a scientific hypothesis that describes how species descended from a common ancestor, diversifying to produce the myriad species that we see today.
All scientific theories make testable predictions. For example, the theory of gravitation predicts that water will flow downhill and that the earth will orbit the sun, instead of flying out of our solar system in a straight line. Just like other scientific theories, the theory of evolution makes a number of predictions. The reason that the theory of evolution is so widely accepted by scientists is because its predictions can be observed to be true in the real world. In this article we’ll look at three of the theory of evolution’s most important and easily understood predictions and the evidence that these predictions are born out.
The mechanism of evolution – How does evolution work?
In order for the theory of evolution to work we need to have a mechanism that passes traits from one generation to another. That mechanism must make imperfect copies of the parents, not identical copies. Generational differences will inevitably confer a reproductive advantage, so those traits will be favored in future generations via natural selection.
When the theory of evolution was introduced, it was obvious that offspring are not exact copies of their parents. However, the mechanism by which traits were passed from one generation to another without creating exact clones was unknown. Since then, Francis Crick discovered the structure of DNA, how it is copied, and that it is the blueprint on which every organism is built. (Actually, that’s every organism except retroviruses, which are arguably alive.)
As the theory of evolution predicts, the copying process is imperfect. When DNA is copied, there can be point mutations, substitutions, deletions, duplications and crossover between chromosome pairs in diploid organisms. This basic mechanism of reproduction was accurately predicted by evolution.
Evolution of new species (called macroevolution) takes place over millions of years with trillions of repeated events in which one trait has a tiny reproductive advantage over another. We don’t expect to see a new species over our lifetimes. However, changing environmental conditions exert new evolutionary pressures. Here, the theory of evolution predicts that we will see the small changes that over many lifetimes may add up to the evolution of a new species.
The real world provides a number of examples of microevolution. We see bacteria becoming antibiotic-resistant in hospitals, cave-dwelling fish that lose their ability to see, dogs that separate into breeds as distinct as Great Danes, Greyhounds, and Poodles, and fish that mature younger as humans do more fishing (2). As predicted by the theory of evolution, we can see traits changing in populations so that they can adapt to their environment.
As an interesting aside, since cave-dwelling fish lose their eyesight because of mutations in different genes, if you breed related fish from different caves, sight can be restored. The further apart the caves are, the more likely that the “blinding” mutations occurred in different genes and the more likely that hybrids will have some ability to see. Just as the theory of evolution predicts.
Fossils of Extinct Species
Evolution creates winners, the species that we see today, and losers, species that once lived but are now extinct. If evolution really occurs, there should be evidence of species that were adapted for their environment at one time, but that do not survive today. Indeed, we can find evidence in the fossil record of animals ranging from dinosaurs to trilobites. The theory of evolution accurately predicts that we will find evidence of species that once existed but that are now extinct.
Unlike the theory of evolution, the theory of Intelligent Design makes no big predictions that are testable in the real world. In fact, one could say Intelligent Design predicts a fossil record with no extinct species, since a designer intelligent enough to design life would not have gotten it so wrong.