I’ve been reading through Intelligent Design 101: Leading Experts Explain the Key Issues (Grand Rapids: Kregel, 2008), which has an appendix dealing with theistic evolutionist Francis Collins’ arguments for common ancestry between humans and chimps in his The Language of God: A Scientist Presents Evidence for Belief (New York: Free Press, 2006). It raised several questions/thoughts:
1) You often hear people say that humans and chimps have 96-98% similar genetic structure, and it can initially seem like a strong argument for common ancestry. But all living things share a great deal of genetic similarity, and the greater the morphological similarity between two living things, the more genetic similarity we find. We have about 40% genetic similarity with lettuce, 60% with fruit flies, 80% with cows, 90% with cats. I’m not a scientist, but in light of these facts, and in light of the great morphological similarity between humans and chimps, isn’t a high degree of genetic similarity to be expected?
2) Supposing for the sake of argument that the genetic similarity between humans and chimps is beyond what we would naturally expect from morphological similarity, does this fact really prove common ancestry? It seems to me that common design can explain the data just as cogently as common descent. All designers use similar building blocks in the construction of different materials. No builder of a house would make every brick differently. No designer of car models would start from scratch each time. To do so would be almost infinitely inefficient. Genetic similarities between humans and chimps – as well as other homologous traits – are only proof of common ancestry if we assume that an ultimate Designer operates differently from all human designers.
Further, Jonathan Wells has pointed out that if genetic similarities and other homologous traits did point us towards common ancestry, it would mess with the Darwinian tree. For example, there is striking similarity between the eye of a mouse and the eye of an octopus – two animals never seen near each other on a tree of life model.
3) Evolutionists – from Dawkins to Collins – make much of the similarity between human chromosome 2 and chimpanzee chromosomes 2a and 2b. It is claimed that this can only be explained by a chromosomal fusion in our past, and that this chromosomal fusion is proof of a link from humans back to chimps. Not being a scientist, I find it difficult to assess the claim that human chromosome 2 must have been formed by a fusion of two prior chromosomes – but supposing there was such a fusion, why should we preclude the possibility that this fusion happened within human history? Luskin and Gage make this point, “the fusion evidence does not tell us whether human chromosomal fusion took place in a line that leads back to a common ancestor with chimps or in an independent line that was designed separately” (p. 223 of ID 101).
4) Evolutionists also argue from “junk DNA,” i.e., DNA that has no purpose for a living creature, and has supposedly been discarded at some point in the evolutionary process. Time and time again, however, scientists have found that DNA which has been thought to have been “junk” plays a crucial purpose in the life of the organism. In light of this history, we should be wary of labeling something “junk” just because it has no known purpose. Even evolutionists such Richard Sternberg and James Shapiro have written, “one day, we will think of what used to be called ‘junk DNA’ as a critical component of truly ‘expert’ cell control regimes” (quoted on 226 of ID 101).
Moreover, for this objection to persuasive, one would have to preclude the possibility that junk DNA was originally designed with purpose but then became “junk” in the recent past, within human ancestry. Again, even when evolution is a possible explanation for the data, it need not be macro-evolution.
5) For all my objections to naturalistic neo-Darwinism, I’m open to creative possibilities in terms of the precise timing and mechanism(s) of how God created humanity, and what kinds of continuity there may be between Adam and an ape. But contemporary evolutionary theory is defined as an unguided, blind process by the current scientific establishment. For example, the National Association of Biology Teachers defined evolution in 1996 as a “unsupervised, impersonal, unpredictable, and natural process.” How can any thoughtful theist make peace with that? No matter where we fall on the “how much can evolution explain?” spectrum, belief in the Christian God places us diametrically at odds with an unguided, blind account of biological origins – which is the reigning paradigm among the current scientific establishment.