Biologist Scott Turner’s Purpose and Desire, In His Own Words
As I have been reading biologist Scott Turner’s new book, I have been highlighting sections that seemed particularly interesting or revealing. The book is complex and wide-ranging, so this covers only a few topics. I hope you find them enlightening.
1. Turner’s book, Purpose and Desire: What Makes Something “Alive” and Why Modern Darwinism Has Failed to Explain It, was bound to raise some hackles, just by the very title. What did happen seems strangely familiar:
[T]his book started out as a sequel to my book The Tinkerer’s Accomplice, which explored what I thought then to be the unsolved and very real problem of biological design. I had included in that book a short chapter on intentionality, arguing that intentionality was not some magical thing; it was in fact the obverse of cognition, which itself found its origins in the homeostasis of the brain “ecosystem.” I thought it was a pretty little idea, not into the weeds at all, but my chapter on intentionality provoked emphatic displeasure from a reviewer writing for the books section of a prominent newspaper. This reviewer was a fellow scientist of some renown, and his displeasure was provoked not so much by what I had to say about intentionality, but by the fact that I had had the temerity to even bring up the subject, which he felt had no place in a book that presumed to be scientific. Fair enough — reasonable people can differ on this. But he had gone on to demand that I should have made known my religious beliefs (I’m a Christian, if that matters, albeit not a very good one). This struck me as strange, even a tad illiberal. Would he have demanded a religious confession from an author whose views he had found more congenial? And what would he have done armed with my confession in hand? You see what happened here: I had raised issues as a scientist trying to explain phenomena in my field of study, but my reflections were seen as being so out of bounds (and threatening, presumably) that they could only be explained by religious motivations that I was trying to sneak into my work. I had clearly struck a nerve.
The conclusion I draw…is that we scientists have a problem with the very idea of purposeful life, and the problem is widespread. To be scientists, it seems that the first thing we must do is put on blinders to squishy ideas like purposefulness, intentionality, and a guiding intelligence. But what if these ideas are central to the phenomenon we are studying — life itself? Can questions of purpose and desire be imposed only from outside the work of science? Isn’t that precisely the opposite of what we, as scientists, should do? Yet, we force ourselves into a Hobson’s choice on the matter: accept intentionality and purposefulness as real attributes of life, which disqualifies you as a scientist, or become a scientist and dismiss life’s distinctive quality from your thinking.
2. We need to be careful about what Turner means by cognition. From various places:
I will make a bald assertion: bacteria (or any living system, for that matter) can be agents because they are cognitive beings. Now, before going any further, I need to insert two disclaimers. The first is that I am using “cognition” in the broadest possible sense I can get away with — to mean simply the mapping of information about the external environment onto the cell’s internal workings. The second is that I am distinguishing cognition sharply from consciousness. I feel compelled to do so because the two are often conflated, with the result that neither can be spoken of sensibly. While the two arguably are related to one another, cognition is relatively straightforward compared with consciousness, which is deep, perhaps unfathomably so. It’s clarity I’m aiming for here, not profundity, and conflating the two only muddies the waters. That said, I can confidently say that bacteria can be cognitive agents because they have embedded in their membranes a suite of cognitive mapping tools. These are in the form of protein receptor molecules that respond to environmental conditions and alter the catalytic landscape within the cell. Cognitive mapping of this sort appears to be a universal phenomenon of cellular life. Our own engines of cognition have similar mapping tools: the photosensitive pigments in a rod photoreceptor are membrane-bound proteins that map the presence of photons into an altered physiology within the photoreceptor cell. So, it seems to be cognition all the way down to the simplest life forms we know. Since cognition is an important component of agency, it follows that bacteria can be cognitive agents, as can any living system. There should be nothing controversial about this assertion, as long as we are careful to frame it correctly.
3. On the origin of life, and the necessity of having cognition first:
If Biology’s Second Law is true and life is at root an expression of the phenomenon of homeostasis, then the origin of life is tantamount to the origin of homeostasis. Homeostasis demands certain things, however — among them at least rudimentary forms of cognition and intentionality. This leads to the very strange thought that the origin of life is tantamount to the origin of cognition and intentionality. Even stranger, cognition and intentionality had to have actually preceded the origin of cellular life.
We can rescue this idea from the loony bin by defining cognition very broadly and generally — as informing a state or process about its environment. Our own very complex cognition should not blind us to the fact that cognition can be framed even in very simple systems, like individual cells, or even simpler. The nerve cells that underlie our own cognitive systems are certainly cognitively aware, but they are cognitively aware in a very different and highly circumscribed way from the large-scale cognitive phenomena in which they participate. An individual nerve cell is cognitively aware of the fluid environment in the brain in which it bathes, and of the chemical signals flung at it by the myriad other nerve cells communicating their own cognitive states, and very likely many other features of its little world.
Similarly, intentionality can be defined very broadly. As I argued in The Tinkerer’s Accomplice, intentionality can be construed as the coupling of cognition to metabolic engines that can shape the world to conform to a cognitive map. Brains produce a very complicated intentionality. If I have a cognitive vision of my office being organized in a particular way, I can do the work to bring my office into conformity with that cognitive map. When my office degrades into inevitable chaos, I do the work again to conform it to that cognitive vision of an orderly office. There is no reason to suppose that this kind of intentionality cannot operate at different scales of life. The microbial mat, for example, is the large-scale emergence of a constructed environment that reflects the awareness of each species of microbe of its local environment, and the reshaping of that environment to bring it into conformity with the microbe’s internal cognitive map of what its surroundings should be.
4. Turner, though he uses teleological language, is not an ID proponent. He has an alternate vision for how the first living things may have emerged.
If we imagine what those first conspiracies of homeostasis must have been like, then we can envision a kind of selection operating between different persistent systems of energy and mass flow. Fitness in this instance will be equivalent to persistence, and persistence will be equivalent to robustness of homeostasis. Persistence will turn on how effectively the present and persistent state of an order-producing thermodynamic system — a kind of memory, keep in mind — can shape its broader environment to bring it into conformity with itself. Fundamentally, this is coupling work to information, which is what relates intentionality and cognition in purposeful living systems. This implies that cognition and intentionality were with life from the get-go, and before cellular life emerged from the living thermodynamic froth.
5. Turner relies on a Lamarckian idea of adaptive homeostasis becoming encoded somehow in another sort of memory system than a genetic one. He offers several alternate reservoirs for memory: membranes, microtubule organizing centers (MTOC), and their cytoskeletons. Jonathan Wells has proposed something similar.
For much of the twentieth century, evolutionary thought has been dedicated to advancing the first — the Darwinian — by marginalizing the Lamarckian alternative. We are by now familiar with the claim: only one form of hereditary memory matters, and that is the hard inheritance embodied in the gene. No alternative is possible because there is no imaginable way the experience of a life lived can soften those hard nuggets of hereditary memory.
It is unimaginable no more, and it is the MTOC that has opened the window on how. The cytoskeleton is not mere scaffolding; it serves as the principal communications network between the cognitive mapping tools of the membrane — the receptors that enable cells to sense the environment — and the physiology of the cell, which includes the expression of the heritable memory. Microtubules position receptors in place on membranes, they hold mitochondria and enzyme complexes in place, and through a collection of mediating proteins called microtubule-associated proteins, they connect the cell’s cognition to its physiology.
Microtubules are the cellular machinery underlying the phenomenon of physiological adaptation. They are also the means whereby physiological and evolutionary adaptation can finally be unified, for the MTOCs also extend their reach into the nucleus, to the chromosomes and the complex architecture of the chromosome that actually defines the gene. This reach is most evident during mitosis, when the cell’s MTOCs bloom into the spectacular spray of the spindle apparatus. It also operates in more mundane and workaday ways to unfold chromosomes, open stretches of them to transcription and expression, and even actively define what genes are. Microtubule-associated proteins also mediate the feedback that closes the loop between soft and hard heritable memory, between physiological and evolutionary adaptation, and between purposefulness and evolution.
Summary: Turner’s book is fascinating, stimulating, and befuddling by turns. He has interesting ideas but little to back them up, and in places the prose goes fuzzy, perhaps because there is little to go on. His ideas are only in the beginning stages, and need to be tested and evaluated, because they are controversial.
For example, we already know that organisms modify their environments to fit their physiological needs, whether it be microbial mats, termite mounds, or human beings. That is not controversial. I find the idea of alternate sources of cellular memory most intriguing, and already there are experiments that support this idea, though more work is needed. This is less controversial, though it goes against the standard DNA-centric model. The idea that in the search for regulatory elements in physiology, more and more control elements are required, until you reach the level where every cell is involved, I find fascinating. It certainly corresponds to the increasing detail at the molecular level everywhere. The thing I have most trouble understanding is his idea that cognition preceded life — if cognition at the most primitive requires membranes and membrane receptors that send signals to the cell’s interior to influence its behavior, then either I have misunderstood, or cognition could not occur until after the first life.
This provocative book deserves to be read and considered by anyone interested in the question of evolution and adaptation. It deals with an important subject — how an organism interacts with its environment. Turner sees organisms as actively receiving information, not in a clockwork, mechanistic manner, but in a holistic manner, where the information is received and processed, then responded to according to the purposes of the organism as a whole. His idea comes from many hours of observing organisms — their purposeful, apparently intelligent striving after goals seemingly beyond their capabilities. Either they do exhibit cognition and intentionality according to something like Scott Turner’s model, or another explanation must be found. If Turner is right, the clockwork, mechanistic, DNA-centric model may have met its match.
Image: Cell mitosis in an onion root, by staticd (Own work) [CC BY-SA 3.0], via Wikimedia Commons.