Adaptation Complex …

The next post in P.Z. Myers’ series on the problems with evolutionary psychology is up, and is entitled “Complexity is not usually the product of selection”. Well, this seems a bit odd to me, so I was of course very curious as to what Myers was criticizing here. And the big complaint seems to be one he summarizes from a post by John Wilkins, which he quotes:

Opponents, largely following Gould and Lewontin’s 1979 attack, tend to assert (often without consideration of the particular attempts to give adaptive explanations) that any and all adaptive hypotheses are cheap and to be avoided. This has the effect of basically eliminating natural selective accounts of anything. But we know that selection is the only process that results in complexity over any time, and the fact there are complex traits among organisms leads to the inevitable conclusion that we should be able to give selective explanations from time to time. I have argued before that we should think of adaptation as a viable hypothesis at all times; but being viable doesn’t make it true. The problem is not that EP or sociobiology makes adaptive hypotheses. They should. It is that they often make them without testing them.

Now, before I go on, let me note here that the complexity that at least evolutionary psychologists seem to be on about is complexity of functionality, and so they are aiming at something like the complexity of an organ like the eye. Which, of course, Dawkins’ “Climbing Mount Improbability” analogy was meant to solve: how can you get the complexity of the eye using natural selection if the eye is so complex that it really only has a benefit if it is fully formed? Well, if I recall correctly Dawkins basically said that the pieces themselves can have some small benefit, and natural selection builds on those, and then finally all of the pieces come together and you have an eye. Putting aside if there really is a credible story for that — Dawkins and others claim there is and I’m not going to argue with them without reading it in detail, and frankly biology puts me to sleep — this is indeed a very natural selection based story, a way to demonstrate that you do get very complex functionalities through natural selection. Wings are another functionality that are often charged with being “irreducibly complex” that advocates of natural selection claim are easily explained using selection pressures. So if Myers is going to go after this, he’s going to be going after a lot of explanations considered critical in the fight against creationism/intelligent design. So he’ll have to be careful …

I will concede the general point: a well-designed and testable adaptive hypothesis is a perfectly reasonable starting point to do science, and I agree that one big problem with evolutionary psychology is that most of their adaptive hypotheses are poorly done. But I’ve highlighted the chunk in the middle that’s just absurd: complex traits are the product of selection? Come on, John, you know better than that. Even the creationists get this one right when they argue that there may not be adaptive paths that take you step by step to complex innovations, especially not paths where fitness doesn’t increase incrementally at each step. Their problem is that they don’t understand any other mechanisms at all well (and they don’t understand selection that well, either), so they think it’s an evolution-stopper — but you should know better.

Of course, the creationists that do that are the ones who are claiming “irreducible complexity”, and so that it could not have evolved using selection. And it seems to me that the most common answer to those is not that creationists don’t understand the other mechanisms that can bridge this gap, but rather that they underestimate the ability of natural selection to select across those stages. Sure, there might be use of other mechanisms in bridging some of the gaps, but does that mean that you aren’t allowed or shouldn’t appeal to, say, the incredible usefulness of vision in explaining why most humans have vision?

In getting into this, Myers claims to “demonstrate” that complex traits can and often do arise from mechanisms other than selection. Now, I’m just a poor country software designer/philosopher, but I don’t really get how his explanation does this. After waxing eloquently about a duplication of a genetic marker, he claims we get complexity through this:

Similarly, there would be other mutations in the population: we could have mutants carrying EAB-EB, for instance, with a more specific second enzyme. We could have mutants that knock out functions in any order: X-EAB, or EB-EAB. All kinds of variants arise by chance mutation, and spread to varying degrees through the population by drift. No selection need be involved, and you get all this complexity in the population arising entirely spontaneously. And a good part of the reason that this can occur is because selection plays no role.

Things get more complex in the absence of selection. Selection, as Wilkins well understands, is generally a conservative process that removes phenotypic variation from the population (with some exceptions). It is precisely the inability of selection to cull all variants that deviate from the successful, well-tested norm that allows novel complexity to emerge.

It seems to me that he’s saying that we have all sorts of complex genetic combinations, and thus complexity. Now, to start with, his explanation of this happening through genetic drift and the like in the absence of selection is a bit shaky, since there is no reason to think that the initial copy and mutations will propagate unless they have benefit and so reproduce more than the others. Sure, if they cause no or little harm they might blend in, but why should they? If the organisms that contained them reproduced no more than the ones that didn’t, why would we expect the percentage of these in the population to change? Yes, additional mutations and the like will introduce more variation, but the numbers of each will stay small unless they have selective advantage or attach themselves to individuals that have selective advantage. And so, sure, you might get complexity but …

… it’s the wrong sort of complexity. Myers has gone out and counted the number of genetic complexities and said “Ooh, complex!”. But none of that sort of complexity is a complexity like that of the eye, or a wing, or of powerful cognitive abilities. Thus, this doesn’t seem to me to be producing a complexity of functionality, and that’s what they’re talking about. By retreating to the genes, all Myers does is prove that he’s talking about something completely different from what they’re talking about, and so his objection is not, in fact, an objection at all.

So let’s look at his real-life example of globins:

Do these phenomena operate in the real world, rather than just hypothetical scenarios? Yes. For example, look at the globin genes. These are found in two clusters, an α cluster with seven genes (including two pseudogenes) and a β cluster with five genes. All the genes are related and similar and function — these are all proteins with heme and oxygen-carrying functions — where each gene has slightly different functions (one may have a higher affinity for oxygen than another) and patterns of expression (one may be expressed at a different stage of development than another, or in a different range of tissues), and we can see specific functional adaptations for each, but their origin has to be in a selectively neutral condition.

A fetal hemoglobin with a high affinity for oxygen is an adaptation when expressed in a fetus, but detrimental when expressed in a pregnant woman (it wouldn’t share oxygen as readily with the fetus). The selective advantage could only arise after the different globins had evolved, and when differential gene expression mechanisms had been coupled to them to assure that they would only be expressed under appropriate conditions. The origin was not a selection event, but the refinement to specific roles probably was.

So, to translate this into what Fodor and Piattelli-Palmarini had said: Selection can only work on traits that already exist; it doesn’t produce them. Thus, once we had globins that had a high affinity for oxygen and ones that didn’t, then selection could filter out so that the hemoglobins in a foetus at least tended to have them and those in a pregnant woman didn’t. So, all he’d be saying here is that the initial production of the trait was not done by selection. This is, again, what Fodor and Piattelli-Palmarini argued … and is not relevant, because evolutionary psychology would be aiming at an explanation of the form “Why is it that foetuses have that globin and not pregnanat women?”, which even in Myers’ description here seems to be “Selection pressures”.

Let me reproduce his quote from Thornton that’s supposed to sum up the issue:

In his posts about our paper, Behe’s first error is to ignore the fact that adaptive combinations of mutations can and do evolve by pathways involving neutral intermediates. Behe says that if it takes more than one mutation to produce even a crude version of the new protein function, then selection cannot drive acquisition of the adaptive combination.

This does not mean, however, that the evolutionary path to the new function is blocked or that evolution runs into a “brick wall,” as Behe alleges. If the initial mutations have no negative effect on the ancestral function, they can arise and hang around in populations for substantial periods of time due to genetic drift, creating the background in which an additional mutation can then yield the new function and be subject to selection. This is precisely what we observed in our studies of the evolution of the glucocorticoid receptor (GR).

In our 2007 paper in Science, we showed that multiple mutations were indeed required for the GR to evolve its specificity for the hormone cortisol; some of the mutations that trigger the change in function are deleterious if introduced in isolation, but others are “permissive”: they have no apparent effect on the function of the protein, but once they are in place the protein can tolerate the other mutations that shift and then optimize the new function.

So if you get a background mutation that might be useful later in combination with other traits, then the explanation for them might not be selection. Or, of course, it might be. But, again, ultimately the explanation for why the function dominates in a population is indeed selection, and that’s what evolutionary psychology is trying to explain. Thus, these objections don’t seem to be ones that can be credibly raised against evolutionary psychology’s research project, and so don’t seem to be objections at all.

So far, I have not seen any objection from Myers that takes out evolutionary psychology without also taking out evolutionary explanations. This is not good … for him.

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3 Responses to “Adaptation Complex …”

  1. Héctor Muñoz Says:

    He is sinking in a pit of mud just to defend a terrible presentation.

    The real underlying problem for Mr. Myers is that many EP conclusions conflict with feminist gender theory which proposes that gender identity is a fully maleable cultural construct.

    My opinion sis that all this reveals the true nature of human consiousness: decisions, afiliations and preferences are mostly emotional responses to our environment of origin: either we accept and internalize it or rebel against it. We will fight real hard to defend our stance no matter what.

    Rational thinking is too hard and time consuming to fully apply it to our whole lives. I read somewhere that people with brain damage that destroyed their emotional capability had real hard time deciding things such as to dine chicken or beef.

  2. verbosestoic Says:

    Hector,

    You’re referring to work like that done by Antonio Damasio, and there are some references to at least a work that mentions it in my essay on psychopaths and autistics. My own theory is that emotion is important for motivation — including the motivation to actually “pick one” — but not so much for making the actual decision itself, and that the more you rely on emotion to make the decision the worse decisions you’ll end up making.

    As for Myers, I do think that the biggest issue is that evolutionary psychology comes up with answers that he doesn’t like. And it may be wrong about those answers. But instead of simply countering those specific charges — which would take a lot of effort — the goal seems to be to attack the entire edifice, which is problematic for a host of reasons. In short, the focus is more on discrediting a field that would even ASK the question, instead of pointing out how the answer is wrong.

  3. Héctor Muñoz Says:

    When I go and shop for a snack I don’t really make a rational evaluation of any kind, I just wander through the shelves until I see something that makes me feel desire for it.

    Marketing strategies are based on emotional decision making: that is why people buy SUVs, not because rational and practical considerations but because they want the emotional boost they get from the status it projects.

    Rational thinking consumes too many resources to apply it to most decisions. I believe most decisions are automated to the emotional response whe get from the perspective of choices. Also many decisions (such as marrying) would hardly be carried on if they were only held to rational scrutiny.

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