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Author Topic:   PZ Myers vs. Adaptationism
Member (Idle past 409 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003

Message 46 of 49 (765501)
07-30-2015 9:25 AM
Reply to: Message 45 by Dr Adequate
07-29-2015 8:46 PM

Evolutionary Medicine: Adaptationist Fail
I'm not trying to make any hypothetical scenarios whatsoever. Over and over I've said that this matter didn't spring fully-formed from MrHambre's overheated imagination. Myers, and Gould and Lewontin, and John O. Reiss are describing the flaws in the way people conceptualize the relationship between adaptation and evolution. Unfortunately, the way we conceptualize such things has consequences in terms of the way we define well-being in individuals and society.

And the problems with adaptationist thinking are easy to see in the matter of evolutionary medicine or EN. Michael Cournoyea at the University of Toronto describes the way an adaptationist approach to medicine has been of limited use to the discipline.

Much of the emphasis in EM’s early research program was on reinterpreting unpleasant and seemingly useless physiological processes as adaptive functions of bodily systems. Fever, vomiting, diarrhea, coughing, nausea, pain, fatigue, morning sickness, anxiety, and even jealousy were reconceptualized as adaptive functions of the body that had evolved to protect individuals from a variety of dangers (Nesse and Williams 1994). Recent papers in EM use the same adaptationist assumptions about humanity’s evolutionary past to justify norms of health and well-being. Solutions to the modern world’s “dietary crisis,” for example, can be found in an evolutionary perspective on nutrition, which highlights the disparity between “Stone Age” diets (the ideal to which we evolved) and current eating habits (which are far from ideal) in terms of quantity, quality, and variety (Cordain et al. 2005; Turner et al. 2008). This perspective also explains why many have difficulty digesting cow’s milk, bread, or root vegetables (Lindeberg 2010). Since the human body has not evolved to eat the kinds of foods consumed in affluent nations today, modern lifestyles have little to no evolutionary precedent. Medical research examining the health benefits of pre-agricultural lifestyles (such as the “Paleo” diet) is increasingly carried under the banner of EM.

Noel Boaz (2002), professor of anatomy and anthropology at the Ross University School of Medicine, refers to such disparities between our ancestral health and our current health as discordances of “adaptive normality,” arguing that such normality is our “evolutionary birthright” (p. 5). Boaz makes it clear that evolutionary thinking—and, it seems, only evolutionary thinking—allows us to understand “what our normal ranges of environment, anatomy, physiology, and behavior really are” (p. 2, emphasis added).

So according to the adaptationists, the evolutionary heritage of traits or processes is the most important thing to understand about them, and the key to clinical practice. However, it turns out that even when EM isn't completely speculative, it's of very little relevance in practice:

Such adaptationist reasoning is disconcerting, because it can be misguided and potentially dangerous when applied to ideals of health and well-being. The program is misguided in proposing that we should define ideals of health and human nature based on speculative claims about humanity’s evolutionary past; it is potentially dangerous in suggesting that the “natural and normal” are best just because they are “natural and normal.” In this circular argument, such naturalizations may then appear to offer powerful justifications for what we should do, despite the worry that our ancestral life-histories are difficult (if not impossible) to test empirically.

If the ideal function of some physiological process is found “in nature,” then malfunction, disease, and illness are interpreted as physiological malfunctions rather than biological variability. In a sense, theory becomes immune from error, since a “biological system can fail to behave as a theory predicts without impugning the prediction: we can say that the system is malfunctioning” (Murphy 2008). To take a controversial example, homosexuality might be pathologized and medicalized as bodily malfunction rather than used to question adaptive ideals of heterosexuality. Normalization and naturalization begin to blur when normative views are subtly naturalized. These concerns are even more salient when adaptationist thinking is used to propose species-wide or racially specific standards of health, rather than considering the complexities of sociocultural dissimilarities or the uniqueness of an individual’s subjective health. EM necessarily precludes these approaches, because it naturalizes and defines health/disease in supposedly objective adaptationist terms. EM may even trade one fallacy of medical normalcy for another, rejecting ethnocentric ideals of health for one that is biocentric, based on speculative ancestral conditions. While these are dangerous normative directions for EM, they might be avoided by reconsidering EM’s strong adaptationist stance.

Again, no one is disputing that humans are the products of evolutionary processes or that certain traits are adaptive. What's being disputed is whether we should define well-being in terms of adaptive importance, or whether the evolutionary legacy of a biological function is more relevant to clinical practice than the sociocultural or personal context of the patient's condition and treatment.

This message is a reply to:
 Message 45 by Dr Adequate, posted 07-29-2015 8:46 PM Dr Adequate has responded

Replies to this message:
 Message 47 by Dr Adequate, posted 07-30-2015 10:47 AM MrHambre has not yet responded

Dr Adequate
Member (Idle past 68 days)
Posts: 16112
Joined: 07-20-2006

Message 47 of 49 (765512)
07-30-2015 10:47 AM
Reply to: Message 46 by MrHambre
07-30-2015 9:25 AM

Re: Evolutionary Medicine: Adaptationist Fail
I'm not trying to make any hypothetical scenarios whatsoever.

That would explain why I called it "his proposed hypothetical situation", rather than yours.

Now, what do you think would happen in a situation such as he describes?

This message is a reply to:
 Message 46 by MrHambre, posted 07-30-2015 9:25 AM MrHambre has not yet responded

Member (Idle past 1493 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007

Message 48 of 49 (765523)
07-30-2015 1:14 PM
Reply to: Message 41 by MrHambre
07-29-2015 12:23 PM

Void evolution
MrHambre writes:

bluegenes writes:

imagine self-replicators in a void evolving with the three processes other than natural selection that Myers identifies as important. In the void, there are no environmental constraints; nothing to promote or preserve what Dawkins describes as functional beauty and apparently "designed" complexity, leaving natural selection as the best explanation of those things without claiming that it is the sole cause of evolutionary novelty.

"In a void"? Setting up a completely unrealistic hypothetical situation doesn't prove a point about natural selection, all it does is allow you to deal yourself a winning hand. You've already decided that "functional beauty and apparently designed complexity" are properties that can only be attributed to natural selection, so in your hypothetical setup, it's by definition impossible for such things to evolve.

It looks like you're the one who's misunderstanding what Myers and others are saying. They're not saying natural selection isn't important to evolution, just that other nonselective forces have to be considered too, particularly when they're necessary precursors to selective processes having any truly adaptive effect in many researched instances.

You seem to have missed the main point I picked you up on, which was that there is nothing in the two sentences you quote from Dawkins that isn't compatible with what Myers is saying in the video. Dawkins (and Darwin, were he alive) would readily agree with your last sentence. Variation is essential to Darwin's theory, and three of the four processes which Myers identifies early in the video (mutation, recombination and drift) are the main identified processes that create variation in populations.

Dawkins is merely pointing to natural selection (the fourth process) as being the creator and sustainer of what might be called "functional complexity". Variation is assumed. If you want a realistic example, Dawkins is saying that you won't get the "functional beauty and apparently designed complexity" of eyes in the absence of the selective environmental factor of light, and selection is the only known process that drives the production of and sustains such elaborate systems in variating self-replicators. Myers would certainly agree.

In cave systems completely without light, organisms will not evolve eyes via mutation, recombination and drift, and those species that arrive from lighted environments with eyes will lose them over time due to those processes.

Incidentally, can you think of any characteristics which are at fixation in the phenotype of our own species that could have become so and remained so without the help of selection at some point? Surely, with all this neutral evolution going on, as P.Z. informs us, in small population groups like ours, there must be a long list?

This message is a reply to:
 Message 41 by MrHambre, posted 07-29-2015 12:23 PM MrHambre has responded

Replies to this message:
 Message 49 by MrHambre, posted 07-30-2015 1:41 PM bluegenes has not yet responded

Member (Idle past 409 days)
Posts: 1495
From: Framingham, MA, USA
Joined: 06-23-2003

Message 49 of 49 (765527)
07-30-2015 1:41 PM
Reply to: Message 48 by bluegenes
07-30-2015 1:14 PM

Re: Void evolution
bluegenes writes:

Incidentally, can you think of any characteristics which are at fixation in the phenotype of our own species that could have become so and remained so without the help of selection at some point? Surely, with all this neutral evolution going on, as P.Z. informs us, in small population groups like ours, there must be a long list?

No need to be snide. I've said a few times that non-selective processes aren't mutually exclusive of selection in evolution. The problem comes in when we automatically start speculating about an adaptive history for a trait, and in the process focus so closely on selective scenarios that we lose sight of the context of the organism and population as a whole.

In Message 46 I described the way Evolutionary Medicine's exclusively adaptationist thinking creates problems in clinical practice: the speculative adaptive history of a condition becomes more important than the treatment of the patient. In a more general sense, adaptationist thinking becomes a method through which to define well-being and normalcy in ways that aren't strictly scientific but can have consequences for the way we view racial and gender differences; the sociocultural context of things like health and diversity gets de-emphasized in favor of more "objective" bases.

This message is a reply to:
 Message 48 by bluegenes, posted 07-30-2015 1:14 PM bluegenes has not yet responded

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