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Thou Shalt Not Put Evolutionary Theory to a Test

Science and Human Origins cover.jpgPaul McBride, a PhD student studying vertebrate evolution in New Zealand, is concerned that religion may be driving the research that Ann Gauger and I are doing, or perhaps that we’ve been driving under its influence. As you might guess, there’s some irony in this. His criticisms of my chapter in Science and Human Origins suggest that he may actually be the one whose scientific reasoning is being impaired by his beliefs.
We all agree that evolutionists are crediting remarkable things to an unguided material process. McBride also agrees with us that this process has significant limitations. In his words: “Evolution is not a process that is capable of producing anything and everything, at all times in all species. It is, conversely, a greatly constrained process.” This being so, surely McBride ought to agree with us that the claims of evolutionists need to be evaluated in light of these constraints. It seems to me that to disagree with this would be to adopt a decidedly unscientific stance.
In essence, the scientific approach here should follow two steps: 1) determine unequivocally what the evolutionary mechanism can do (present tense) by performing experiments with appropriate mathematical models used to interpret the results, and 2) determine whether the things that evolutionists claim it did do (past tense) marry up nicely with what we’ve found that it can do. Ann and I have invested heavily in this undertaking, and we have some work to show for it. I can’t fault McBride for not investing in it, because the evolutionary community he finds himself in certainly doesn’t cater to this. For him to adopt their aversion to critical analysis of Darwinism, though, is regrettable.
Like many of his peers, McBride seems to thinks it’s illegitimate to suggest that laboratory tests showing what evolution can’t do have anything to say about what it can do (or did do). Ann and I conducted experiments to find out how many changes would have to occur in a particular enzyme X in order for it to begin performing the function of another enzyme, Y. We found that they are too numerous for unguided evolution to have accomplished this transformation, even with the benefits of a massive bacterial population and billions of years. Having carefully made the case that our chosen X and Y are appropriate for the aims of our study, we think this result has catastrophic implications for Darwinism. McBride disagrees:

The real question is not “Can X be turned into Y?” because that sense of direction requires preordination, which is not theorized to be a part of evolution. If we remove this preordination, the question becomes “Can X turn into something else?”

In my book chapter I compared our X-to-Y conversion to the challenge of converting one golf club into another — a putter into a pitching wedge. Now, if someone were to claim that there’s a natural unguided process that refashioned not just golf clubs but thousands of other things as well, producing a great variety of extraordinarily sophisticated things from humble starting points, the scientist in me would want to see some evidence to back that claim up. Cruise missiles from roller skates? Really? Smart phones from flashlights? Are you sure about that? And my skeptical stance would naturally intensify if I were to find that this highly touted process can’t actually produce a pitching wedge from a putter in the time it supposedly performed all these miracles.
Not everyone approaches the subject from a skeptical stance, though. McBride wants to say that because evolution operates in an unpredictable hit-and-miss way, one documented miss doesn’t mean anything.
Really? If we’re going to be scientific about this, shouldn’t we withhold judgment on that until we’ve put some effort into step 2 above? In particular, shouldn’t we pay some attention to the fact that evolution has to explain invention on a much larger scale than we examined — not just single new enzyme functions, but the suites of these needed for new metabolism, often requiring completely new protein architectures… and not just new architectures at that molecular level, but also at the level of cells, and tissues, and body plans? If evolution is hit-and-miss at the very bottom level of this hierarchy, how would it ever succeed at the top level, which depends so critically on the lower levels? That would be like struggling with simple words in Japanese but being fluent when it comes to high-level conversation. It’s not just unlikely. It’s incoherent.
The importance of step 2 — reconciling what we know evolution can do with what we claim it did do — was precisely my intended point near the end of the second chapter of Science and Human Origins. There I laid out the experimental evidence that would be needed to show that an evolutionary transition from apes to humans is indeed feasible. McBride misconstrues my challenge in his haste to dismiss it:

Axe is suggesting that until the day that each single mutation leading from a common ancestor with chimpanzees to man is predicted in order, with each mutation individually investigated for its fitness effects, there is still room to argue about holes in evolutionary theory and leave room for the calm, guiding hand of the Intelligent Designer.

Again, he’s focusing exclusively on the past, whereas I’m asking evolutionists to do what other scientists do when they aim to say something credible about the distant past. They do the work of connecting it in a credible way to the present. They base their claims about what did happen on their understanding of what does happen. Before scientists claim that a natural process produced humans from apes, they ought to spend some time reflecting on what would have to be true in order for this really to happen within the constraints that McBride has acknowledged.
For example, McBride criticizes me for not mentioning genetic drift in my discussion of human origins, apparently without realizing that the result of Durrett and Schmidt rules drift out. Each and every specific genetic change needed to produce humans from apes would have to have conferred a significant selective advantage in order for humans to have appeared in the available time. Any aspect of the transition that requires two or more mutations to act in combination in order to increase fitness would take way too long (>100 million years).
My challenge to McBride, and everyone else who believes the evolutionary story of human origins, is not to provide the list of mutations that did the trick, but rather a list of mutations that can do it. Otherwise they’re in the position of insisting that something is a scientific fact without having the faintest idea how it even could be. That’s just not what scientists should be doing.

Douglas Axe

Maxwell Professor of Molecular Biology at Biola University
Douglas Axe is the Maxwell Professor of Molecular Biology at Biola University, the founding Director of Biologic Institute, the founding Editor of BIO-Complexity, and the author of Undeniable: How Biology Confirms Our Intuition That Life Is Designed. After completing his PhD at Caltech, he held postdoctoral and research scientist positions at the University of Cambridge and the Cambridge Medical Research Council Centre. His research, which examines the functional and structural constraints on the evolution of proteins and protein systems, has been featured in many scientific journals, including the Journal of Molecular Biology, the Proceedings of the National Academy of Sciences, BIO-Complexity, and Nature, and in such books as Signature in the Cell and Darwin’s Doubt by Stephen Meyer and Life’s Solution by Simon Conway Morris.