Tuesday, January 12, 2010

Embodied Physiology
J. Scott Turner is a professor in the Department of Environmental and Forest Biology at State University of New York, Syracuse. He is the author of two books, The Extended Organism and more recently The Tinkerer's Accomplice which I review (along with Richard Dawkins' latest, Greatest Show on Earth) in this month's issue of Catholic World Report. (Some of this post repeats what I offered in the article, which is not online.)

Turner occupies an interesting ground in his field. One might be tempted to say a middle ground between strict Darwinian adaptationists and intelligent design advocates, but that would be oversimplifying the matter.

His early work in South Africa and Namibia studying termite mounds, prodigious natural chimneys of earth out of all proportion in size to the small termites that build them, did not turn him into a Darwin skeptic, by any means, but it did prod him to realize how important the role of environment is to the survival and flourishing of a species. In his own words, it made him wonder about the old dilemma of Cleanthes, presented in Hume’s Dialogue Concerning Natural Religion, caught between Philo the reductionist skeptic and Demea the Platonist. Is there room for talk of intentionality in nature without causing both sides in the ongoing evolution debate to run for the barricades? 

Turner thinks there is, and the key is what he calls embodied physiology. Modern evolutionary biology as we understand it, which is to say variation via genetic drift, mutations, duplications combined with the pruning filter of natural selection, certainly explains a great deal. But as has been pointed out by evolutionists in the past (notably the late Stephen Jay Gould), these mechanisms of evolution don’t explain everything.

Instead of looking for God in the gaps, however, Turner’s work prompts the reader of his book to hearken back to what Aristotle and the Greeks called the physis, or nature of organisms. Turner finds homeostasis (defined here as environmental equilibrium) and the agents that manifest it as processes that work along side Darwinian evolution to bring about successful function.

He writes (on p. 149):
Though Darwin and Wallace delivered the death blow to the purported intentionality of what organisms are, they did not invalidate the very different kind of intentionality that underpins what organisms do. At first glance,  this might seems a trivial shortcoming. Darwinism requires only that good function be possible and that it be heritable; beyond that Darwinism is agnostic about the details of either. That is why Darwin himself could credibly propose his theory while being completely ignorant of the mechanisms of heredity. Yet the intentionality implicit in physis is at the very core of the Darwinian concept of adaptation: forming well-functioning machines that can carry an organism through the filter of natural selection. It is no wonder then, that intentionality is such an emotive issue for evolutionary biology. The fact of evolution itself cannot be rationally explained with intentionality, but the means whereby evolution works cannot be explained rationally without it. Arguably, modern biology has broken under the strain.
Turner’s answer to the question of how intentionality arises in nature is to argue that biological intentionality is itself a form of homeostasis.

The agents of homeostasis Turner calls Bernard machines. This is a term first coined by Cosma Shalizi, professor of statistics at Carnegie Mellon, and named after the great 19th century French physiologist Claude Bernard. Bernard machines are organic devices that can be found everywhere—osteoblasts  in the bones, fibroblasts in the blood, epithelial cells in the eye and nerve cells in the brain—that are, Turner writes,  “frankly teleological, imbued with the goal-seeking behavior and purposefulness that is at the heart of homeostasis.”

Turner’s book explores how Bernard machines in various guises work to bring about designedness in a wide range of living systems.

The eye, of course, has long been a favorite example for both Darwin proponents and skeptics because of its intricacy. But Turner points out it’s not merely a matter of how the eye itself is designed to capture an image.

“Indeed, an optical eye seems to be a fairly easy thing to evolve,” he writes. “Photosensitivity is not much of a big deal: many common membrane lipids can act as ‘light antennas,’ complicated molecules whose electrons are put into a tizzy when a photon crashes into them.” The real miracle, he goes on, lies not so much in the optical eye, but in the computational process that produces vision in the brain. And that visual system, he argues, represents an embodied physiology, melded structure and function both wrought by systems of Bernard machines—in this case, synaptic alliances between  brain cells—that impose homeostasis on the environments in the brain they create. The visual system comprises not just the retinas in our eyes, but many ‘retinas’ located throughout the brain, each of which ‘sees’ the world differently but all coming together into a coherent vision in the primary visual cortex.

This is just one sample in very general terms. I highly recommend reading his book, more than once.

The Tinkerer’s Accomplice has not drawn a great deal of attention from Design proponents. But Turner hasn’t drawn much attention from the ultra-Darwinists either. This is a shame, for both sides in the modern replay of Cleanthes’ dilemma could benefit from a re-introduction of classical teleology into the discussion. I have no interest in the intelligent design approach to 'purpose', which I find uninteresting scientifically and philosophically. But I think there are grounds for a return to, or at least a reconsideration of, teleology as Aristotle and later philosophers such as Aquinas understood it.

Over the past few months I had a chance to send Scott some questions to discuss his work and teleology further.

JF: Ed Feser had an interesting post a while back about how both sides of the ID/evolution debate misunderstand classical teleology. The ID types think proving teleology in nature means the existence of a Agent Designer (i.e., God) will be much easier to demonstrate, and the militant atheists shun teleology basically because ...they agree. But Ed argues--rightly in my opinion--this is because both sides misunderstand Aristotle and Aquinas.


My first question is, as a scientist, do you feel based on your experience that this is true: i.e., that your colleagues who are materialists/atheists react to the subject of teleology negatively because they think it is intrinsically tied to an ID perspective?

Scott Turner (ST):  I'm inclined to agree with Ed Feser, but not completely. It's obviously true that the ID issue is pretty polarized, needlessly so in my opinion, and I agree that there has been a bit of "closing of minds" on "my" side about purposefulness (or teleology), largely because ID has been pushing the issue so publicly, and also because of a bit of a "those icky creationists are back" mindset. Yet the whole issue of purposefulness and teleology has been at the heart of evolutionary thought since before Darwin, and there's been quite a lot of deep thought about it since, I think. Unfortunately that's all been submerged by the heat of the current rhetoric (Richard Dawkins and his cult followers have done us no favors in that regard.). This has pushed the more superficial arguments to the fore which can easily give the impression that the two sides are largely ignorant of the issue. So Ed Feser is correct in that regard. It does not credit the fact that there's a pretty large body of biological thought that has grappled seriously with the idea.

I decided to write The Tinkerer's Accomplice in part because I thought biological design was a serious and unsolved problem, and in part because I thought both the Neodarwinist and ID camps were missing something essential about the problem. In short, I wanted to write a book that took the issue of design seriously and proposed a scientifically credible way forward. Even the hint of design was a red flag, however. I had people refuse to review the book, and reviewers who branded it a "stealth ID" book. One reviewer opined that I was a "closet deist", and I recently found myself described as a "known creationist." I never knew that about myself! And there has been some private correspondence from colleagues that, to put it mildly, surprised me. So the issue itself does seem to unhinge people a bit. But on the positive side, there have been many people who have taken the time to consider the book seriously and to work through the ideas carefully and to tell their friends. So, even though the reception of the book was a bit negative at first, it's slowly getting more positive.

JF: Do you think teleology gets short shrift because--from a methodological stance-- most evolutionary biologists think it's really not much use anyway? In other words, unless teleology can make some predictions or offer some obvious questions worth researching (something the Intelligent Design movement has repeatedly failed to do), scientists just can't be bothered with it?

ST: We biologists are trained to think very skeptically about teleological arguments, and rightly so, I think. Again this mindset has long predated the ID issue. In fact, I think ID is so emotive because it has inflamed already latent tensions in our thinking rather than caused them.

While there is clearly a radical materialist/Neodarwinist school of evolutionary thought, evolutionary biology is not monolithic in this regard. Evolutionary developmental biology (evo-devo) is probably the most prominent area that has grappled seriously with the issue of teleology. Niche construction theory is another.

JF: Could you give a brief summary of what niche construction theory is?

ST: The principal mover in niche construction is John Odling-Smee, an anthropologist from Oxford. He is co-author, with Marcus Feldman from Stanford and Kevin Laland from St Andrews in Scotland, of the book Niche Construction: The Neglected Process in Evolution. Niche construction basically develops the idea that I wrote about in The Extended Organism and to some degree in Tinkerer's Accomplice, namely that organisms modify environments to suit their biology, that they create their own "ecological niches" rather than evolving to fit existing "niches".

I think it's a very powerful idea, but in my opinion, I think it suffers from the same problem that most neo-darwinist ideas do, namely that it is agnostic about how good function comes to be.  There's also the whole problematic concept of the "niche", which was an outgrowth of Sewall Wright's attempts to reconcile adaptationism with the comparatively atomist perspective of Ronald Fisher. I've always thought it to be a fairly empty metaphor: the principal "evidence" for its existence is the phenomenon--adaptation--it is intended to explain.

ST: [ Back to the previous question ] For the most part, these disciplines are trying to reconcile the obviously purposeful nature of embryonic development and ecology with the materialist/atomist mindset of modern Darwinism, but there's still a group of people (of which I'm one, Lynn Margulis and Simon Conway Morris are two other voices far more prominent than mine) who think the two are probably irreconcilable. In this sense, the issue is not so much methodological as it is philosophical: do we explain the world as a product of blind (if biased) chance, or is there something that guides it? And if the latter, what precisely is doing the guiding? Right now, I think we're at a very exciting time in evolutionary biology because the idea is emerging that we are now bumping up against the limits of the materialist/atomist philosophy, and are coming to realize that there is indeed something special about life that simply must be understood. There are various opinions out there about just what that special quality is (my two cents is the special quality of homeostasis), but no matter how it comes out, I think we're on the verge of a major philosophical shift in biology. This is what I find most interesting about ID. Even though I think it's the wrong philosophy, I think it has to be regarded as one aspect of an emerging larger philosophical critique of the materialist view of evolution.

JF: In a book like yours, I'm sure there were a lot of other species and systems you didn't have space to discuss. And several of the chapters discuss systems within the human body (bones, digestive system, the brain). Can you discuss a few other species, like the termites and their mounds of chapter one, that you think offer interesting examples of embodied physiology? (I realize you probably discussed these in more detail in your previous book The Extended Organism, but perhaps you could briefly offer them here.)

ST: Even though the focus in The Tinkerer's Accomplice was on design in organisms, one of the points I've tried to develop in both my books is that physiological function operates at multiple scales, both within the body, with its organizational hierarchy of cell-tissue--organ etc, but also as "embodied physiology" outside the organism. In fact, this kind of embodied physiology is ubiquitous. Termite mounds are a particularly unavoidable example, but there are many many more. Coral reefs, for example, are organs of extended physiology for the colonial polyps that build them, operating as an interface between water and organism that aids in the capture of energy for the polyps. The interface even scales fractally, just like in the lung. There are crickets that construct burrows that are shaped like trumpets to focus the acoustic vibrations from their wings. Some other crickets cut holes in leaves and then position their bodies in the whole, making the leaf like the cone of a loudspeaker. Plants construct incredibly complex micro climates. And the tendency extends as far as the biosphere, even though we might find it hard to see. For example, one reviewer of my first book complained that this idea of extended physiology couldn't possibly work. This insight came to him while he was flying over the Midwest, which led him to reflect that living things couldn't possibly modify environments on a scale so vast. To which I could only reply, "Well, how about the atmosphere you're flying through?" The atmosphere is, in fact, a biological construct.

JF: The discussion of persistors at the end of the book, those environments such as the termite mounds that date back over a thousand years, raises the question of whether across the wide spectrum of species on earth we can't discuss the extent to which organisms have influenced the global environment over the eons, rather than the other way around. Putting it simplistically, the standard Darwinian view is natural selection works independently, filtering out the species that come into and fail to adapt to their environments (i.e., variation proposes, nature disposes); but it seems your work is suggesting the possibility that the roles could be reversed, and species through embodied physiology become successful enough over time to 'select' their environment. Or is that overstating it?

ST: No, it's absolutely not overstating it. This notion of the environment as selective filter ("the organism proposes, the environment disposes"--I've seen this quote attributed to both Stephen Jay Gould and Richard Lewontin ) is one of the many metaphors that bolster the Darwinist idea of natural selection. The metaphor falls down a bit when organisms become masters of their environment rather than its slaves, though, because now organisms are essentially selecting themselves. This paradox has been around for a long time, in fact, and attempts to resolve it date back to Sewall Wright's ideas of "adaptive landscapes" and Hutchinson's notions of ecological "niches". Deep down, though, those are just propping up the metaphor with another metaphor. The same can be said of ideas like the Baldwin Effect, which is essentially a refinement of the adaptive landscapes idea.

What I have tried to do is cut through the metaphors a bit, to get to the actual mechanisms whereby adaptation works--in Edward Cope's felicitous phrase, to understand the "origin of fitness"--and I've been led, somewhat reluctantly, to the conclusion that we've not been thinking about adaptation and natural selection properly. This is not to say that we've been thinking about these things incorrectly, just that we have not been thinking about them comprehensively enough. Since the early parts of the 20th century, we have been thinking about adaptation and natural selection as genetic processes. That's perfectly fine, but what's missing is a coherent view of the physiological dimension, the living systems that make adaptation possible. And that dimension plays by very different rules--physiological rules, like homeostasis--that aren't derivable from first principles of natural selection. A coherent theory of evolution will account for both. Currently, it doesn't, in my opinion.

JF: In an earlier email, you wrote: "Right now, I think we're at a very exciting time in evolutionary biology because the idea is emerging that we are now bumping up against the limits of the materialist/atomist philosophy, and are coming to realize that there is indeed something special about life that simply must be understood. There are various opinions out there about just what that special quality is (my two cents is the special quality of homeostasis), but no matter how it comes out, I think we're on the verge of a major philosophical shift in biology." 

I assume you see specialists like Sean Carroll (Evo Devo) on this side? And Kirschner and Gerhart (The Plausibility of Life). In your experience is there already a clear cut divide, for example, when biologists get together at conferences and symposiums, where the reductionists are more vocal and hostile to teleology and the other side content to keep working away at the research and entertaining different theories of how designedness comes about?

ST: I'm not sure I'd describe it as a divide so much as a re-emerging perspective. Ever since the rediscovery of Mendelian genetics, there's been this debate about the role that genes play in Darwinian evolution. At first, of course, the rediscovery of the Mendelian gene was thought to be the death knell for Darwinism. This is what makes the Neodarwinist synthesis--the reconciliation of Mendelian genetics with Darwinian natural selection--one of the greatest intellectual achievements of all time. Once that was achieved, though, the question became whether genetic natural selection could explain everything (what might be called the "parsimonous" explanation), or whether there is something else involved. Richard Dawkins, of course, has been the most vigorous defender in our time of the "parsimonist" idea. But even though, for much of the 20th century, the scientific case seemed to be swinging decisively in favor of the "parsimonists", the other side never really went away, and it has re-emerged in schools like evo-devo, or niche construction theory, or in Simon Conway Morris' ideas about the importance of convergence. Most of these ideas that are bubbling up are, in fact, rooted in older ideas--evo-devo draws heavily on the work of D'Arcy Thompson, for example, who was a trenchant critic of Darwinism--that were part of an incredibly rich intellectual debate over evolution that was thriving prior to the modern synthesis. Those other perspectives submerged for a while, just because the modern synthesis seemed to settle so many things. But we're seeing now that even though it solved a lot, it didn't settle everything. And that is why, in my view, we're seeing these ideas emerging anew.

Of course, that's not to say the debate isn't heated. For the most part, that's fine--it helps keep us all honest. But it does have its down side. For example, I often run into criticism of my notion that homeostasis makes evolution a far more intention-driven process than the Darwinist idea can comfortably accommodate. Nearly always, the criticism is that intentionality is not necessary, that we can explain everything without it--the parsimonist idea. Never mind that it actually can't explain everything--there's no good Darwinist explanation for the origin of life, for example--but there's a deeper issue. The parsimonist defense of Neodarwinism usually invokes Occam's Razor--always go for the simpler explanation. But this is a fundamental misreading of Occam's Razor, which really says that you must not make hypotheses without necessity. If you don't believe intentionality is a real phenomenon, than invoking it is indeed unnecessary. But what if intentionality is real, actually is a necessary attribute of living things? Then in this case Occam's Razor becomes Occam's blinders. Which is never a pleasant thing to hear.

J. Scott Turner's book at Amazon.

Next on my book shelf is John Wilkins' Species: A History of the Idea.

3 comments:

TheOFloinn said...

AA few years ago, I ran across a four-fold Aristotelian explanation of evolution. I no longer remember who wrote it; but it ran:

1. Material Cause:
the tendency to variation due to constant small random mutations in the genetic code; i. e., a variety of differing individuals within a species capable of transmitting their differences
2. Formal Cause:
the tendency of interbreeding population to reproduce itself in a stable manner and increase in numbers; i. e., the maintenance of type
3. Efficient Cause:
natural selection by the environment which eliminates those variants which are less effective in reproducing their kind; i. e., the agent determining in which direction species-change will take place
4. Final Cause:
the flexibility of living things by which they are able to occupy new niches in the changing environment; i. e., a feed-back mechanism which guides the selective process toward a new type which can exploit new environmental possibilities

The fourth "because" seems quite a bit like what Dr. Turner is saying and, come to that, something I've been saying. That living organisms have an intentionality and work to keep on living. I suggested that, given a mutation that does not outright incapacitate an organism, that organism will seek out some manner of exploiting that feature, find a work-around, perhaps modify their behavior or their environment. A finch does not develop a certain size and shape beak because it exploits a certain kind of seed. It exploits a certain kind of seed because of the size and shape of its beak.

John Farrell said...

Now that's a cool profile photo!

It would be interesting to track down that Aristotelian explanation for future reference.

Speaking of which, this would be a great panel for Boskone.

"Does Teleology Have a Future?"

:)

TheOFloinn said...

I googled it to here:
http://www.morec.com/nature/evol.html

attributed to Benedict Ashley 1972: 211-212 (summarizing the causal analysis of John Deely of evolution as "a return to the conception of science as reasoned facts, distinct from and superordinate to mathematized facts": Deely 1969a: 132)

The referenced works are
Benedict Ashley, "Causality and Evolution", The Thomist 36.2 (1972): 199-230
and
John Deely, "The Philosophical Dimensions of The Origin of Species, Part 1", The Thomist 33.1 (1969): 75-149

The links to both appear to be broken, so I can't get back any further. Deely looks interesting. http://www.morec.com/semiotic.htm