Actually, if I hadn’t liked the alliteration, I wouldn’t have used “falsifying” in the title. What I really want to assert is that none of the key ideas in Neodarwinian theory (taken as the heart of evolution) are either verified or logically capable of being demonstrated empirically, let alone falsified. This has been said before, but it’s worth reiterating, because we’re still being told it’s as factual as gravity…
Let’s start with more precise definitions of evolution such as “change in gene frequencies over time.” I guess there’s little dispute that gene frequencies in populations can change over time, so this one could be falsified, and in that sense has been found true. But as a definition of evolution it’s been falsified by the many other mechanisms known to be at least a part of evolution. Could one justly claim that the phrase “change in gene frequencies” covers hybridisation events, whole genome doubling, chromosome fusions and so on, quite apart from the emerging role of epigenetic mechanisms, which aren’t genetic at all? This definition also makes the still unverified assumption that it applies to speciation as well as microevolution. But, as I’ve said before, it’s a geneticist’s definition, and “macroevolution is studied by palaeontologists.”
I’m actually more interested in the fundamental universals of Darwinian theory. Take “random mutation”. Although this idea first concentrated on ionising radiation mutations, considered then truly stochastic, biologists nowadays will usually decry ones total misunderstanding of evolution if you say “random”, and tell you that “randomness” means solely “random with regard to fitness”. This is just as well, as a host of work nowadays shows how much control organisms exhibit over changes to their genome. Even ionising radiation actually triggers specific damage control mechanisms followed by certain patterns of mutation.
So one has to wonder if at least some, if not all, of these cell-mediated mutations are not only non-random, but quite deliberate. And if not, how could one tell?
But, as I said, it’s “randomness with regard to fitness” that counts. So we first need to define fitness, so that we can find ways of judging whether these mutations constitute randomness, cellular intention, or in between, badly-organised cellular intention. The problem is, of course, that never in the 150 years since Darwin has “fitness” been adequately defined. “Differential reproduction” has been suggested, but that only tells you that what survives, survives. In the context of mutations, it means that since you found the mutation in a live organism, it has a degree of fitness.
But what degree? It’s quite difficult to tell, isn’t it, unless it’s such a gross mutation that it causes sterility in the lab? In the wild, how are you going to control for a predator or the weather wiping out an entire brood by chance, independent of your mutation? So you have to take fitness as an axiom – in real life, fitness, whatever it is, may have very little to do with survival, and indeed the neutral theory accepts that to be the case much of the time. Fitness, then, is unverifiable because it’s unmeasurable and undefinable.
In any case, people like Stephen Gould reject such a definition of fitness, saying that “fitness” refers to specific traits that lead to differential reproduction. But in the real environment it’s the total organism, not individual traits or still less individual mutations that survives, or not. A mutation that makes a black animal white might make a difference to survival in the snow. But Darwin had subtler things in mind – human breeders, he said, can only look on the surface but evolution, like God, considers the heart. Yet even granted that a single mutation’s effect on fitness could be assessed, how does that prove it was random? You have not disproved the possibility that the organism caused the mutation, or took advantage of it rather than correcting it. You haven’t even demonstrated that angels didn’t cause it miraculously.
Perhaps we’ll have better luck with the key concept of natural selection? This, after all, is the non-random, design-illusioning powerhouse of the Neodarwinian scheme. Except, of course that it’s lost much of its prestige in recent years as the evolutionary process. We’re back with the neutral theory, and with purifying selection, and with purifying selection being swamped in the higher animals (as per Koonin). Nearly all the variant theories, it must be said, still assign a central role to adaptive selection, though you often get the impression it’s lip service rather than enthusiastic support. That, and some desperation as it’s the only suggested naturalistic mechanism for new form and function. The neutral theory (according to some) describes neutral phases of evolution with stasis, interspersed with phases of adaptive selection, perhaps in an isolated population, where all the good bits happen.
It is rather a pity that the adaptive phases always seem to happen somewhere else, and in some distant epoch, because otherwise we could verify it empirically.
And what are we verifying? Well, actually, just the inverse of the indefinable “fitness”. Natural selection is a synonym for “survival of the fittest”, and I’ve already suggested how impossible it is to verify fitness. Plausible though it is, all we really observe is that some organisms survive to reproduce more than others. If that’s due to natural selection, it’s as much the result of nature selecting those not to be buried by a volcano or fried by a meteor as any assumed, and unmeasurable, biological superiority. There’s actually no intrinsic reason why the fittest should survive rather than the luckiest in the world outside the laboratory and the livestock breeder, seeing that we have no way to measure it.
Natural selection, as we need to remind ourselves, has no explanation for the arrival of the fittest. And it is a vague and unverifiable process for sorting which will survive when they do. “Deliver me some pterosaurs,” it says (it is a watchmaker after all, if blind), “and I’ll kill the unfit ones.” Well, somebody else (non-random mutations? The cell? God?) produces the design, and some of them do die. But you have only natural selection’s word for it that it was the unfit that failed to reproduce. Or, to step outside the metaphor, you have only Darwin’s word for it. And as I read today in the wise words of a historian of science:
Here I think we will eventually find the secret of Darwins greatness, in two traits not always praised in theories of how to conduct yourself scientifically. One is Darwins notorious habit of jumping to conclusions without adequate evidence. He developed his coral reef theory, we remember, before examining coral reefs. The other is that of stubbornly maintaining his theories regardless of the valid arguments and evidence that could be brought against them. [Cannons note at this point refers the reader to the argument over the Parallel Roads of Glen Roy paper.]
These are the procedures to be recommended, of course, only to the great; and I come to the regrettable conclusion that science takes great strides forward not primarily from laborious research, but rather when some biased person maintains his intuitions in public, and when, thereafter, generations of scientists find that some of these intuitions do actually illuminate whatever work they are doing. (W Cannon, Victorian Studies 5: 109-134, 1961)
