DNA Evidence for Evolution

QUESTION: What is the DNA evidence for evolution?

ANSWER:

DNA molecules are complex molecules which contain the assembly instructions for every living creature. Certain aspects of DNA have been interpreted as evidence for Darwinian evolution. DNA evidence for evolution includes mutations, genetic similarities among species, so-called “Junk DNA” and “Pseudogenes.” Here we will look at these evidences and briefly make note of some of the criticism levied against them by opponents of Darwin’s theory.

The fact that mutations can corrupt DNA is important for the Darwinian paradigm because in order for an organism to eventually evolve into an entirely different organism, changes must be made to the creature’s genome over time. But Darwinian evolution needs more than just change. It needs an increase in genetic information. Critics point out that genetic mutation does not appear to provide a mechanism for that increase. In fact, there appear to be genetic limitations to the potential for biological change. As biophysicist Dr. Lee Spetner explains, “. . .Reptiles and birds are very different. Reptiles have no genetic information for wings or feathers. To change a reptile into a bird would require the addition of. . .complex information. . . . I really do not believe that the neo-Darwinian model can account for large scale evolution. What they really can’t account for is the build up of information. . . .And not only is it improbable on the mathematical level, that is theoretically, but experimentally one has not found a single mutation that one can point at that actually adds information. In fact, every beneficial mutation that I have seen reduces the information, it loses information”¹

Genetic similarities between species are also interpreted as DNA evidence for evolution. The fact that human and chimp DNA are more than 96% the same is taken to mean that humans are genetically related to chimps and therefore descended from a common ancestor. Opponents of Darwin’s theory point out that there is a certain degree of genetic similarity to all living systems and that the more similar two species are, the more similar their DNA should appear. “The DNA of a cow and a whale, two mammals, should be more alike than the DNA of a cow and a bacterium. If it were not so, then the whole idea of DNA being the information carrier in living things would have to be questioned. Likewise, humans and apes have a lot of morphological similarities, so we would expect there would be similarities in their DNA. Of all the animals, chimps are most like humans, so we would expect that their DNA would be most like human DNA.”²

The final category of DNA evidence for evolution which we will look at concerns Junk DNA and Pseudogenes. Junk DNA are segments of DNA whose function remains a mystery. We do not know what they do. Darwinists believe that Junk DNA are similar to vestigial organs in that they are useless vestiges from our evolutionary past. Opponents of the theory point out that just because we do not know what something does, that does not mean that it does not serve an important function. Consider vestigial organs. Back in the 19th Century there were dozens of organs which were designated “vestigial” because scientists could not figure out what they did. These, like Junk DNA, were interpreted as evidence for Darwin’s theory. Of a list of 86 put together by Robert Wiedersheim, one of Darwin’s disciples, only a handful remain ambiguous at the present time. Scientists have discovered important functions for all of the rest.

Similarly, we do not know much about Pseudogenes. Scientists believe that they are genes which have lost their function through mutation. As John Woodmorappe explains, “Arguments for shared evolutionary ancestry have been advanced based on the similarities in perceived disablements found in orthologous pseudogenes (counterpart pseudogenes in other primates).” Woodmorappe goes on to say however, “. . .A close examination shows that this presumed evidence is equivocal. Dissimilarities between the pseudogenes of presumably related organisms are at least as prominent as the similarities, and similarities in orthologous pseudogenes can arise independently of shared evolutionary ancestry.”³

The debate over DNA evidence for evolution rages on. Too much remains unknown at this current stage. Hopefully, as time goes on and we learn more about DNA we will be in a better position to know whether or not DNA truly supports Darwin’s theory of evolution.

This article is also available in Spanish.