Creation and Science: The Primary Scientific Considerations
Geological evidence. A range of different dating methods indicate that the earth is 4.6 billion years old. The primary way of establishing this is based on radioisotopes: atoms within rocks which have unstable nuclei that decay over set periods (106,000 million years for samarium-147 to neodymium-143, 18,800 million years for rubidium-87 to strontium-87, 1,260 million years for potassium-40 to argon-40, 700 million years for uranium-235 to lead-207, 5,715 years for carbon-14, and so on). To supplement this method of dating, tree rings can be counted and amalgamated – one example in central Germany goes back to 8400 BC – and the results can then be compared with other dating methods. The same is true of layers in the Antarctic ice cap, where one 3190m core has reached ice which looks to be 740,000 years old. And then the rates of sedimentary rock erosion (a famous example would be the Grand Canyon, but there are many others) can be measured, and cross-checked with other methods. Taken together, within a relatively small margin of error (2% for radioisotopes, and up to 10% for ice cap layers), such dating methods agree, leading to an estimated age for the earth of about 4.6 billion years. Similar methods suggest that all sorts of animals (not just dinosaurs!) have been dying on earth, and even becoming extinct, for many millions of years. These conclusions are shared, to my knowledge, by every geologist working in a research university or oil company in the world today.
It is of course possible that all of these methods have results which converge because of methodological distortions, fraudulent scholarship or mistaken assumptions. The first two of these possibilities are extremely unlikely, unless we are to suppose a large-scale conspiracy amongst research scientists (many of whom, of course, are Christians anyway); errors of that nature would likely have been discovered by now. The third one is the most commonly alleged within evangelical circles – we cannot, it is argued, back-project modern dating methods to previous eras, especially if we consider the cataclysmic impact of a global flood – but there are huge problems here as well, for the simple reason that we have a wide range of different dating methods converging, all of which would need to have been affected by (say) the global flood to indicate exactly the same age. This, I would suggest, is implausible. Consequently, any theory of origins needs to deal with the geological evidence that the earth is old, and that animals have been dying for a very long time.
Cosmological evidence. The primary way of calculating the age of the universe is by measuring the levels of cosmic background radiation, and then from that approximating the cooling time of the universe since the Big Bang, to produce a result of around 13.7 billion years. Again, though, the result can be cross-checked with the various predictions made on the basis of the expanding universe (a fascinating story that I briefly summarised in If God Then What?), and existing models for stellar evolution, which indicate that the oldest stars in the universe are around 13.2 billion years old. Again, these conclusions could all result from poorly interpreted data, or even falsification; but since both sources of error are typically rooted out by the rigours of peer-review, this seems very unlikely. An acceptable model of origins, then, needs either to account for these data points in different and compelling ways, or to accept that the universe is of something like that age.
Palaeontological evidence. As most people with even a passing interest in this subject will know, the fossil record is by no means as full as palaeontologists would like it to be, for the simple reason that the vast majority of animals that die are not fossilised, but eaten by predators and subjected to weathering on the earth’s surface. (The statement of Ross from Friends in debate with Phoebe, that “you can literally see [fossils] evolving”, is therefore an overstatement, and not just because the word “literally” is being misused.) Nonetheless, palaeontological evidence for Darwinian evolution exists, in that the Darwinian model has predictive power. The theory of evolution makes all sorts of predictions about what species should emerge where in the fossil record – the classic example quoted is that if a rabbit appeared in the strata below the Cambrian explosion, Darwin’s theory would fall at once – and to my knowledge, thus far, none of these predictions have been shown to be incorrect. There are plenty of positive predictions that have not yet been verified (X should appear after Y, but we’ve never found X or Y), but none that have been debunked (we’ve just found X and Y, and they’re back to front). Predictive power is a huge strength when it comes to a scientific proposal, and as such, the fossil record provides evidence that favours Darwinian evolution. This, too, needs to be factored in to any model of origins.
Genetic evidence. As soon as it is conceded that animals and humans have genes, and that these genes are produced in accordance with their DNA, it quickly becomes obvious to all of us that our DNA must overlap fairly closely with that of the great apes. (My moment of revelation on this point can be dated to the morning I stood in Washington Zoo, staring at a gorilla as he performed his morning ablutions. To say it was like looking in the mirror would be to flatter myself.) For some time, the popular debates around creation and science have focused on this obvious overlap, but without resolution. The reason for this is not hard to see: if God had wanted to make a person who looked very similar (relatively) to a bonobo or a chimpanzee, and if he had wanted to use DNA as the code to determine the genes of different creatures, then we would expect humans and bonobos and chimpanzees to have almost identical genes, and almost identical DNA. To argue that one must be descended from the other, on the basis of these similarities alone, would be like arguing that the Vauxhall Insignia must be “descended from” the Vauxhall Vectra, simply because their major design features are extremely similar. Such similarities, on their own, do not conclusively favour either model.
But that’s by no means the whole story. Not every part of the genome, you see, is directly related to physical characteristics. Pseudogenes, which are genes that no longer appear to have a function but once used to, sit there like genetic fossils in our genomes (we have upwards of 19,000 of them), demonstrating our relationship to our biological ancestors. Denis Alexander uses the analogy of a thirty-digit number being tattooed onto every one of our descendants, which has no purpose other than to highlight our relationship to one another - and then points out that our genetic tattoo is shared with the great apes. Jumping genes, which are the “copy and paste” genes which sit in the non-protein encoding part of our genome, are another indication that we have the same ancestry as other primates, since these strings of nucleotide pairs appear in exactly the same sequence in orang-utans. Then there are retroviral insertions, perhaps the clearest evidence of all. When viruses infect a host, the host incorporates the viral DNA into its cells, whether or not the virus harms the host. When the host has offspring, these retroviral insertions appear in the same part of the genome - and yes, we have retroviral insertions that exactly match those of other primates. In other words, either we share the same ancestry, or God put exactly the same bit of corrupted genetic code into both of us to make it look like we do. That’s why scientists regard genetics, rather than the fossil record, as much the most compelling evidence for evolution we have - and any model of origins needs to account for it somehow.
So that’s a summary of the main scientific considerations we need to keep in mind when talking about origins. Before I finish, though, I want to explain the main objection to evolution that I had for many years, and why I now believe it is thoroughly misleading. When I was about nineteen, I read Wayne Grudem’s Systematic Theology - a masterful, sweeping, brilliant resource of a book that I still use regularly, and for which I remain extremely grateful. But in his chapter on creation, Grudem made much of the objection (which I shared for over ten years) that evolution is fundamentally random, and that this therefore puts it at odds with the biblical doctrine of creation. Three lines of thought have subsequently convinced me that he was wrong about this, and that I was too.
The first is theological: the fact that nothing in God’s world is ‘random’, in the sense of undetermined or unknown, even things that appear random to us. “The lot is cast into the lap, but its every decision comes from the LORD”, says Proverbs 16:33. All sorts of things look random to us, but are not random under the providence of a sovereign and loving God. What could look more random than the process by which we come to exist? Millions of sperm swimming towards an egg, and one of them wins, apparently by chance; but of course we believe (rightly) that the winning sperm was ordained by God, since “in your book were written the days that were formed for me, before they came to be” (Ps 139:16). Or what about coastal or fluvial erosion? Thousands of little particles being flung at a cliff or a riverbank over the centuries, apparently in an unsorted, unguided melee - yet we have no qualms about singing that God “shapes the valleys and brings the rain”, and nor should we. Even in Scripture, we have an arrow that is fired “at random” (1 Kin 22:34) that was foretold by God through the prophet Micaiah (1 Kin 22:13-28). In God’s world, nothing is random, no matter how much it might look like that to us. So I don’t see why evolutionary processes, like erosion and plate tectonics and sex and the water cycle, couldn’t be governed by God, even if they appear random to humans.
The second reason is that evolution, when properly articulated, is not ‘random’ even on its own terms. Richard Dawkins rightly makes much of this point: the most advantageous adaptations are selected, not randomly assigned, with the criterion for selection being the benefits they bring to the creature’s reproductive prospects. So repeating the idea that ‘evolution by chance’ is not plausible does not really advance the discussion. Nobody thinks it is.
The third, and the most controversial (but also the most fascinating), is the fact that evolution, as a process, keeps producing the same results, which indicates to some that it has a purpose built-in. The late Stephen Jay Gould insisted that if evolution was to happen again, it would produce totally different results to the ones we now have. But scientists like Simon Conway Morris at Cambridge, who is also a Christian, have pointed out how frequently evolution gives the same outcomes (a phenomenon known as ‘convergence’): features like the camera eye, the mimicry of ant morphology in insects and spiders and the retention of the live egg in reptiles have all come about separately, on dozens of occasions, in the evolutionary tree. From this, Conway Morris has suggested that evolution has a telos built in, and that human life is almost inevitable, given earth’s properties, from an evolutionary point of view. If he is right, it would indicate that not only is the process of evolution not random, but nor is the result.
There is much, much more that could be said about all this, and those looking for a layman’s introduction to the issues might want to read Denis Alexander’s Creation or Evolution: Do We Have to Choose? on the evolutionary side, and John Lennox’s God’s Undertaker: Has Science Buried God? on the ID side. I am also aware of how conceptually, emotionally and spiritually confusing (and exhausting) it can be for many of us to wrestle with this stuff; it certainly has been for me at times, in the last few years. For the moment, then, my hope is to flag the primary scientific considerations in the discussion, in between two posts about what the Bible says, with a view to fitting everything together in the last week of the series. Bear with me!