Biblical creationism offers two explanations for what we see in nature: “God did it” and “the Fall did it.” Such theology often argues that God created nature perfectly and corruption entered into the world after the Fall. Such things like blind cave fish are explained as post-Fall degeneration. Such theology often argues that any similarities observed between “unrelated” organisms are due to common design. This is often invoked to explain similarities between humans and other creatures, because biblical creationism holds that humans are not related to any other species. However, these explanations are unable to account for common design flaws, which are features that are clearly biological flaws but are shared between organisms that are supposed to be unrelated. Unary pseudogenes are an excellent example of this problem for biblical creationism.
Humans, chimps, gorillas, and other primates lack the ability to synthesize ascorbic acid (vitamin C) and must eat a diet that includes it to survive. Other animals are able to synthesize ascorbic acid because they have a complete metabolic pathway. However, humans et al. are missing a key enzyme, L-gulano-gamma-lactone oxidase, which is involved in the synthesis of ascorbic acid. However, we do have the non-functioning remains of this gene still in our DNA, as do other primates which have been studied: chimps, gorillas, orangutans, and macaques. In all five species the gene is broken in the same way (deletion of same exons) and is found in the same place in the genome.
Biology explains this shared flaw by proposing that in an ancestor of all five species, a deletion occurred in the L-gulano-gamma-lactone oxidase, rendering it non functional. This deletion was then passed to its descendents, producing the pattern that we see today. Biblical creationism is unable to explain it because either God would have to have made a flawed creation or humans would have to be related to other species. Neither are options that biblical creationism allows.
I have proposed this problem many times to biblical creationists who insist that humans do not share a common ancestor with any other species. None of them have yet to account for this interesting fact of nature.
- Nishikimi M et al. (1994) “Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-gamma-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man.” Journal of Biological Chemistry 269: 13685-13688
- Ohta Y and Nishikimi M (1999) “Random nucleotide substitutions in primate nonfunctional gene for L-gulano-gamma-lactone oxidiase, the missing enzyme in L-ascorbind acid biosynthesis.” Biochimica et Biophysica Acta 1472: 408-411