I’ve gotten my hands on a review copy of Michael Behe’s new book, “The Edge of Evolution”. The shortest version of a review is: Bad science, bad math, and bad theology, all wrapped up in a pretty little package.
As people who’ve followed his writings, lectures, and court appearances know, Behe is pretty much a perfect example of the ignoramus who makes a bad argument, and then puts his fingers in his ears and shouts “La la la, I can’t hear you” whenever anyone refutes it. He *still* harps on his “irreducible complexity” nonsense, despite the fact that pretty much *every aspect* of it has been thoroughly refuted. (The entire concept of IC is a pile of rubbish; the entire argument about IC is based on the idea that evolution is a strictly additive process, which is not true; there are numerous examples of observed evolution of IC systems, both in biology and in evolutionary algorithms. But none of these facts makes a bit of difference: like the energizer bunny of ignorance, he just keeps going, and going…)
Anyway, the new book is based on what comes down to a mathematical argument – a mathematical argument that I’ve specifically refuted on this blog numerous times. I’m not mentioning that because I expect Behe to read GM/BM and consider it as a serious source for his research; even if I were an expert in the subject (which I’m *not*), a blog is *not* a citable source for real research. But I mention it because the error is so simple, so fundamental, and so bleeding *obvious* that even a non-expert can explain what’s wrong with it in a spare five minutes – but Behe, who apparently spent several *years* writing this book still can’t see the problem. (In fact, one of the papers that he cites as *support* for this ridiculous theory contains the refutation!)
Behe’s argument is that what’s commonly referred to as the theory of evolution is actually made up of three parts:
1. Common Descent: all living creatures are derived from common ancestors by modification. I’m not quoting Behe’s explanation of this here, because it’s
astonishingly muddled for such a simple idea: he’s so eager to start throwing in
his digs at the idea of evolution that he muddles the explanation of common descent
with irrelevant gibberish. In fact, his explanation of this reads almost like an
endorsement of John Davidson’s “prescribed evolution”.
2. Natural Selection: Michael Egnor’s favorite. As Behe states it (on page 2 of TEoE), “the idea of natural selection says just that the more fit organisms of a species will replace the progeny of the less fit”.
3. Random Mutation: again, quoting Behe: “the only way a plant or animal becomes fitter
than its relatives is by sustaining a serendipitous mutation.” In the expansion of
this, he handwaves his way around, basically asserting not just that mutation is
random, but that the only kinds of mutation are single-point changes: no duplication, no frameshifting, etc.
This is already poor stuff – the muddled version of his explanation of common descent; his presentation of a shallow tautological form of natural selection; and his ignorance of any source of genetic diversity other that mutation.
As soon as he gets through that muddled explanation, he starts to launch his attack in earnest. And it’s a sad attempt:
>In the past hundred years science has advanced enormously;
>what do the results of modern science show? In brief, the evidence
>for common descent seems compelling. The results of modern DNA
>sequencing experiments, undreamed of by nineteenth-century
>scientists like Charles Darwin, show that some distantly related
>organisms share apparently arbitrary features of their genes that
>seem to have no explanation other than that they were inherited
>from a distant common ancestor. Second,
>that random mutation paired with natural selection can modify life
>in important ways. Third, however, there is strong evidence that
>random mutation is extremely limited. Now that we know the
>sequences of many genomes, now that we know how mutations
>occur, and how often, we can explore the possibilities and limits of
>random mutation with some degree of precision–for the first time
>since Darwin proposed his theory.
This is a careful verbatim quote from his book. What I found astonishing here is that he
asserts his conclusions in this paragraph as settled fact, *without even attempting to cite any evidence*. It’s typical, but pathetic. It’s not like he doesn’t use citations and footnotes through the book – he sometimes insert supportive citations of completely
trivial things. But this incredible statement: that “there is strong evidence that random mutation is extremely limited”, he doesn’t even *attempt* to support.
The rest of the book focuses an this alleged problem: that random mutation is somehow constrained, and can’t produce the necessary changes to explain the diversity of life.
The part of the book that is most annoying to me, and thus the part that I’ll focus the rest of this review on, is chapter three, “The Mathematical Limits of Darwinism”. This is, basically, the real heart of the book, and for obvious reasons, it seriously ticks me off. Behe’s math is atrociously bad, pig-ignorant garbage – but he presents it seriously, as if it’s a real argument, and as if he has the slightest clue what he’s talking about.
The basic argument in this chapter is the good old “fitness landscape” argument. And Behe makes the *classic* mistakes. His entire argument really comes down to the following points:
1. Evolution can be modeled in terms of a *static, unchanging* fitness landscape.
2. The fitness landscape is a smooth, surface made up of hills and valleys, where
a local minimum or maximum in *any* dimension is a local minimum or maximum in *all*
3. The fitness function mapping from a genome to a point of the fitness landscape is
4. The fitness function is smoothly continuous, with infinitessimally small changes
(single-point base chanages) mapping to infinitessimally small changes in position
on the fitness landscape.
Of course, Behe doesn’t phrase it like that; in fact, I doubt that he even understands
that he’s making those assumptions: His grasp of math is extremely shallow, and his mathematical reasoning is glib at best.
First, I’ll repeat [what I've said in the past about what's wrong with each of these assumptions][landscape]. Then I’ll put out a couple of examples in the text of how Behe attemps to refute these criticisms, and show what’s wrong with them.
Behe uses these assumptions about the fitness landscape, and the search process which is his model of evolution, to build his argument. He frequently talks about how things can get *trapped* at a local maximum. By Behe’s reasoning, once a species reaches a local maximum of a fitness landscape, that’s the *end* of any process of change in that species. When he talks about a *limit* of what can be done by mutation+selection, that’s what he’s talking about: the idea that local maxima are traps.
This is one of the oldest canards of the IDists: the mis-modeling of evolution as a search process over a static landscape. The problems with this are quite simple:
**First**, It assumes that the fitness landscape is fundamentally low-dimensional. If the fitness landscape truly has many independent dimensions, then there are very few (if any) true local maxima. To assume that local maxima are common requires assuming that when moving through one dimension brings you to a local maximum, moving through any other dimension will also bring you to a local maximum *at the same point* – which is really another way of saying that the dimensions are *not* independent – they all reach maxima and minima at the same places.
The idea of local maxima and minima being common comes from thinking of things in terms of low-dimensional surfaces. A fitness landscape with two variables forms a three dimensional graph – and in three dimensions, we do frequently see things like hills and valleys. But that’s because a local minima is the result of an interaction between *only two* variables. In a landscape with 100 dimensions, you *don’t* expect to see such uniformity. You may reach a local maxima in one dimension – but by switching direction, you can find another uphill slope to climb; and when that reaches a maximum, you can find an uphill slope in some *other* direction. High dimensionality means that there are *numerous* directions that you can move within the landscape; and a maximum means that there’s no level or uphill slope in *any* direction.
(As an interesting aside, IDists, when they’re quoting Dembski, like to talk about the No Free Lunch theorems. The NFL theorems are based on the idea that landscapes really aren’t smooth – that they don’t have uniform properties that permit a search strategy to work. Behe’s argument totally contradicts that – the kinds of landscapes that must be considered to make NFL work totally devastate Behe’s idea. )
**Second**, Behe assumes that the landscape can’t change. If it’s a local maximum today, it’s a local maximum tomorrow. The reason that he needs this is obvious: if todays local maximum can stop being a maximum, then it’s not any kind of a barrier. The argument *requires* that the landscape never change.
This is the biggest problem with the whole idea of modeling evolution as search over a fitness landscape: landscape search generally assumes a static landscape. But this doesn’t match reality at all. Just consider a simple example. Suppose you’ve got a local maximum in the landscape, and that that maximum represents a fitness point for a plant-eater: that point represents an adaptation to a diet that’s based on some kind of vegetation, and a behavior that protects it from predation. Because it’s a maximum, things that get anywhere near it end up climbing the slope to that maximum. The local maximum becomes a clustering point for plant-eating species. The fact of that clustering means that the population at that point is going to grow.
The growing population means that you’ll be creating another fitness point on the landscape: a point for a predator. That point didn’t exist before: when there wasn’t a population of plant-eaters for a predator to consume, there would be no advantage to evolving to fit the niche of eating the creatures that eat the vegetation; once there is a population of plant-eaters there, then you’ve got a new fitness point.
The growing population also means that the fitness of that point may start to decline: too much competition for the resources. Too many creatures trying to eat the same limited food source.
This is the reality of the “fitness landscape”: the landscape is shaped from the species that inhabit it; as the species change, the landscape changes. Those *traps* that Behe keeps talking about only exist if the landscape *doesn’t* change. But the only way that the landscape doesn’t change is if the species in it don’t change. The moment any species starts climbing a hill in the fitness landscape, the landscape must change to describe the new circumstances.
**Third**, Behe, as in his IC gibberish, insists on a monotonically increasing fitness function, *and* he insists on mutation behaving as a continuous function. According to Behe, the *only* changes are changes that produce an *immediate*
increase in fitness. So if you’re at a local maximum, there’s no way to escape it, because you can’t go *downhill*. There are two problems here: one is that it’s possible for a species to become *less* fit; the other is the continuity assumption.
With respect to that first issue, it’s possible in many circumstances, for a population to become *less* fit. When a species is not under strong selective pressure, it’s possible for numerous neutral or even slightly negative mutations to accumulate in the population. There’s nothing in reality preventing that: mildly negative mutations *do* occur in reality. In Behe’s model, that means that in reality, evolution isn’t a strict hill-climber; crossing a valley to get to a higher fitness summit is *not* impossible.
The second part if this is a *huge* problem for Behe’s argument. Behe wants to be able to argue that local maxima are traps. A local maxima is only a trap for a search process if the search has certain strict limitations: the search needs to behave as an *almost* continuous function. This is a bit messy, because we’re straddling the line between continuous math and discrete math here. But the idea is that Behe’s model is that there’s a function from a species genome to a point in the fitness landscape; and that mutation makes an small change to the genome, and that that small change to the genome *must* correspond to a proportionately small change in the mapped location on the landscape. So mutations can only produce small changes; and small changes can only result in small motions on the landscape. That means that the evolutionary search process can’t *jump* valleys in the landscape.
The problem is, that doesn’t correspond to reality. There are times when a small change can have a huge impact. The classic textbook example of this is the Panda’s thumb: a very small genetic change caused a change in the developmental process in the wrist of the panda, which produced what is effectively an extra thumb. The genetic change that produced this is *tiny*; the effect is huge. This is not an unusual thing: small changes can have huge effects. But small changes with large impacts totally blow Behe’s argument out of the water: they mean that Behe’s barriers *aren’t* barriers at all.
So Behe’s argument fails miserably, because it’s built on a pile of *obviously*
invalid, long-discredited assumptions. And yet he builds his entire book around them – and just acts as if the assumptions were obviously correct, and no one has ever refuted them. Even when the sources that he cites contradict him, he acts as if there’s nothing wrong: he cites several papers about modeling evolution with a fitness landscape that specifically discuss the dimensionality issues, and then *in the same paragraph as the citation*, talks
about the fitness landscape as a surface in three dimensions. The only explanation I can find for his is that he really doesn’t understand most of the math that he’s talking about. (I don’t think that Behe is above deliberately lying; but I think he’s smart enough that he wouldn’t cite things that contradict him so blatantly if he understood what they really said.)
Behe isn’t *entirely* ignorant of the criticisms of the landscape arguments – he does devote some space to arguing around them. Anyone care to guess what kind of argument he uses? Anyone?
What’s the favorite bullshit mathematical argument of creationist assholes worldwide? Why big numbers, of course! He starts to slap together some sloppy probabilities to argue how unlikely it is for a mutation to jump valleys in a fitness landscape. He goes through a
really sloppy argument about how unlikely it is for malaria to evolve chloroquine resistance, arguing that the odds of evolved resistance are one it 1020. Now, when you realize that each person infected with Malaria has *billions* of malaria cells in their bodies, and that number starts to *not* look so scary anymore: *billions* of cells reproducing daily in *millions* of individuals, which has been going on for decades of chloroquine use, and you start to realize that that’s not such a big number after all. But even so – it’s a *deliberately* inflated number, relying on things like the monotonicity assumption, and the assumption that resistance is all-or-nothing. But even with those sleazy assumptions, that number just isn’t compelling when it comes to malaria. So, he tries to take the inflated malaria number, and wave his hands around by applying it to human beings, because we reproduce so slowly compared to malaria:
>If all of these huge numbers make your head spin, think of it this
>way. The likelihood that Homo sapiens achieved any single mutation
>of the kind required for malaria to become resistant to chloro-
>quine–not the easiest mutation, to be sure, but still only a shift of
>two amino acids–the likelihood that such a mutation could arise just
>once in the entire course of the human lineage in the past ten million
>years, is minuscule–of the same order as, say, the likelihood of
>you personally winning the Powerball lottery by buying a single ticket.
What’s particularly astonishing about this is that even this rotten argument – taking an artifically inflated probability number based on the peculiarities of the biochemistry of one specific organism, and applying it to a completely different organism (waving hands
furiously to try to distract from the fact that it’s just nonsensical to cross that way), contains its own refutation. Yes, perhaps the odds of this happening are similar to the odds of winning at powerball. But the fact is *someone wins* the powerball lottery. He wants to pretend that it’s unlikely by pointing at *you specifically*, and saying that it’s like *you* winning the lottery. But in fact, the power of evolution is that it doesn’t just try *one thing*. It’s not a process of *one mutation*, wait and see if it works out and fixes in the population; it’s not a process with a predetermined destination. It’s a process of countless mutations happening at the some time – some propagate, some don’t – and if *any* of them work, then they take over. The real chance of evolution producing *something* are like the chances of *someone* winning the lottery. The chances of them producing humanity taken a priori are like the chances of *you* winning the lottery; but since humanity was *not* a predestined result, the chances of the evolutionary sweepstakes producing *something* is like the chances of *someone* winning the lottery – i.e., virtually inevitable.
Finally, I said that not just is Behe’s book bad science and bad math, but it’s bad theology. Behe claims to believe in an all-knowing, all-powerful God. But at the same time, his entire book is based on the argument that God created life on earth, and got it all going using an evolutionary process. But then, according to Behe, over and over again, his creation was woefully inadequate of facing the actual challenges that it would face, and so his all-powerful creator needs to *constantly* intervene, and tweak things in order to make them work. His God is a buffoon – a bumbling fool who isn’t capable of creating worlds in a way that *works*. Reading his book, I’m actually shocked that he’s a religious person: he’s clearly never bothered to think through his beliefs, and what his theories say about them. Again and again, reading the book, I kept finding myself saying two things: “How can this guy call himself a scientist, when he argues so sloppily?”, and “How can this guy be religious when he apparently believes that his creator isn’t capable of getting *anything* right?” Following Behe’s argument, it seems like it should be impossible for Behe’s god to have done the things Behe claims that he did, because they’re too hard for such a bumbler.
I’m sure that that aspect of Behe’s book isn’t deliberate. But it’s typical: he seems to be incapable of actually really thinking about an argument in any way deeper than asking “Does this agree with my conclusion?”; and even then, he doesn’t seem capable of recognizing when an argument *doesn’t* support his conclusion. It’s really appalling. Frankly, I’m really
shocked that this guy ever managed to get tenure anywhere – judging by his writing, he’s not particularly bright; he’s a remarkably disorganized and muddled thinker; and he’s incapable of comprehending or responding to arguments made by other researchers.
*(Note: several typos: a missing “not”, a missing “resistance”, and “got” for “god”, “lest” for “less” were corrected in the above. That’s what I get for trying to write in short bursts while waiting for builds.)*