Purpose and Desire Read online

I’ve never been able to stand the sight of blood. Even the thought of it sends a cold shiver up my spine.

  This is an unfortunate handicap for a physiologist like me. As it is mostly practiced today, physiology is a medical discipline. Being a research physiologist therefore usually means studying people, or animals that are similar enough to people so that what we learn from them might be useful for people. Studying people is obviously out for me: the involuntary look of horror that sweeps over my face at hearing of someone’s injuries, even fake injuries depicted in a television show, would alarm my patients and immediately disqualify me. Nor am I any better when it comes to the animal proxies physiologists commonly use: dogs are some of my favorite people; cats intrigue me with their airs of exotic disdain; rats and mice reveal wonderful hidden personalities once they decide you are not trying to eat them. Don’t even mention chimpanzees.

  Fortunately, I’ve always found some way to work around my squeamishness. I studied alligators for a time. I rationalized this by an appeal to fairness: they could turn the tables and eat me, after all, and without a shred of remorse. Birds’ eggs (or more precisely, birds’ embryos living in eggs) sufficed for a while: I suppose it was easier to work on something that couldn’t look me in the eye, at least as long as I didn’t allow it to hatch. Finally, there were termites, whose built structures fascinated me and which live in societies where life is cheap and the massacre of multitudes is routine. What would it matter if a few thousand more were sacrificed on the altar of science?

  And that is the path that led me one day to a grassy field in northern Namibia, about to do diesel-powered surgery on two termite mounds.

  It started off as a whim. The previous evening, my friend Eugene Marais and I were sitting outside at the research farm where I do my work, enjoying a beer—well, maybe more than one. We had been observing the termites’ ability to repair small wounds inflicted on their mound—a hole drilled in the side, that sort of thing. Somehow these creatures—stupid, blind, and clumsy as individuals—knew en masse precisely where damage had been done and could mobilize a horde of nest mates to repair the damage, quickly and efficiently. We wanted to know how they pulled it off.

  I don’t remember who had the idea first, but the gist of our brainstorm was to quit fooling around with little hurts to the mound. Rather, we wondered what would happen if we just lopped the whole thing off? “Complete moundectomy” was our flippant term for the procedure we were contemplating. And because these were termites, we could act on our whim—glorious freedom!—safe from the bureaucratic killjoys who would have to be given a say if we were studying a creature that had a backbone.

  So we got busy the next morning selecting and preparing a couple of mounds for our frivolous experiment. The day after that, we brought in a front-end loader and scraped both mounds right off at the ground. Because these termites’ colonies are located underground, deep below the level where the blade of our machine would cut, the “patients” survived the procedure just fine and immediately began to rebuild their mounds. For the next ninety days or so, we visited our subjects daily and photographed their progress, always from the same vantage point. When our time in the field was at an end, we lined all the photographs up in my computer and made a time-lapse movie with them.

  We had a rough idea what our movie would show. The mounds had regrown to about their original size and shape, even reproducing the mounds’ prominent northward tilt. That was not a surprise, although how quickly the termites did it was—about three months for a construction project that involved gathering and moving about three tons of soil up into the growing mound. But the time-lapse video revealed a dimension to the reconstruction that could not quite be captured by beginning-and-end comparisons. To me, these mounds were alive: pulsing, heaving themselves up from the mud like hideous beasts; sometimes like cockroaches, shying away from the intense sun; sometimes aiming defiantly right at the sun, as a moth flies to a flame. These were no mere piled-up heaps of dirt; they were beings that knew what they were supposed to be and were intent on becoming it.

  But attributing sentience or intentionality to such a thing is an impure thought in modern biology. Intentionality is subjective, vague, and unquantifiable, making it dangerously easy to project your own persona onto what you are observing. This is why modern scientists are trained from conception to view the world from a stance as far removed from sentience as possible, to explain what they see as the product of the relentless flight of multitudes of atoms (or termites) hurtling willy-nilly. If you have to fall back on fuzzy ideas like intentionality, that’s prima facie evidence that you’re not thinking about it hard enough: real scientists do it reductively.

  There’s virtue in this, of course. Scientists are as prone to flights of fancy as anyone, and this cold-eyed reductionism usually serves us well as a check on our natural exuberance. Virtue can be too scrupulously applied, however, and when it is, well . . . to paraphrase Mr. Bumble, science, like the law, can be idiotic.*

  And this is the dilemma those time-lapse videos presented: the mounds certainly looked alive, but were they alive? The reductive reflex is to say, “Of course the mounds weren’t alive, how could they be?” For one thing, none of the criteria we usually apply to distinguish the quick from the dead seem to fit. The mound has no genes, it doesn’t reproduce, and it doesn’t breathe. No matter how complex its structure and hypnotic its form, it’s still just a pile of dirt, no more alive than a cloud in the sky.

  But the impression from those time-lapse videos was compelling, and there comes a point for all scientists when they have to decide whether to believe the plain evidence of the senses, even as every lesson of their scientific training admonishes them not to. To properly judge the matter, we must therefore look critically at our criteria for deciding whether such a thing as a termite mound is alive or not.

  Certainly the termites that build the mound qualify as alive, but what precisely qualifies them so? The usual criteria we biologists invoke are genes, reproduction, and metabolism. So, which apply to termites? Genes and metabolism the termites certainly have, but the workers that build the mound do not reproduce, leaving that chore to their fecund mother, the queen. So, if the workers score two out of three, are the workers then two-thirds alive, leaving only the queen to taste life’s full measure?

  Blithe sophistry, you say? Well, how about just metabolism, then? That certainly seems to be a distinctive trait of life, which even the worker termites have in full: they breathe, they eat, they keep their bodies in good trim, they avoid inevitable death as best they can. Surely the mound cannot lay claim to that?

  Again, let’s not be so quick to leap to what might seem the obvious conclusion, because we first need to ask, What precisely do we mean by metabolism? Here, we run into a little problem of language: a termite is not an is as much as it is a does. It is a highly ordered stream of matter and energy, which takes the ephemeral form of a termite, that is continually built up as fast as it breaks down.

  What about the mound? Well, that too is more of a verb than a noun. The mound is highly ordered and dynamic—rain and wind strips it of nearly a quarter ton of soil each year, which the termites must assiduously replace, grain by grain, just as the myriad cells in a termite’s body must do with every atom that flows through them. And the soil grains are replaced in a highly specified way that sustains the mound’s ephemeral form, if not its actual substance. What, then, is the difference between termite and mound? At this fundamental level, it’s hard to see.

  If we can’t rule metabolism out of bounds for the mound, that leaves genes as the essential disqualifier of the mound as alive. I’ll have much more to say about genes later, but for now I’ll just assert that the matter, like metabolism, is actually not so clear-cut. All living things, as far as we know, possess some form of hereditary memory, that is, some way of replicating in the future what was successful in the past. Genes, by virtue of their ubiquity, are marked as a very (and that is understating the case) successful f
orm of hereditary memory. So successful is this form of hereditary memory that every living thing on Earth uses it. This does not preclude the existence of other forms of hereditary memory, however.

  Let me illustrate using the supposedly non-living termite mound. The mound far outlasts the lifetime of any worker that builds it: a mound persists for the lifetime of the queen, more than a decade, while each worker has a life expectancy of a couple of months at best. If a colony dies and a new colony takes up residence in the vacated mound, the mound can even, at odds of about one in four, persist many years more. In that sense, a mound is the bequest of one generation of workers (or one colony, no longer living) to a subsequent generation. The mound, therefore, is as much a hereditary legacy to the termites occupying it as the strands of DNA inherited from their parents. The context, form, and longevity of the memories clearly differ, but the mound embodies hereditary memory all the same.

  So, what is the best guide for answering what should be a simple question: is this animated heap of soil alive or isn’t it? Do we trust our cool reason, which says that it is not, or our emphatic intuition, which says that it is? As we have just seen, cool reason seems only to lead us into a muddle, leaving the seemingly rational view—that the mound is clearly not alive—exposed as more prejudice than truth. To stick with the rational view is in fact to fall back on an article of faith—that even inconclusive reason is better than the emphatic intuition that the mound is indeed alive.

  This uncomfortable spot is the starting point for the broad question that will be my theme throughout this book: do we have a coherent theory of evolution? The firmly settled answer to this question is supposed to be “yes,” because Charles Darwin gave us a way to apply cool reason to answering life’s mystery of mysteries—the evolution of life in its “endless forms most beautiful,” even unto beings that can contemplate their own origins. Now I want to be very careful how I say what I next wish to say, because it could easily be misconstrued. I intend to argue in this book that the answer to my question might actually be “no.”

  That qualified “no” may lump me together, in the eyes of some, with others identified as anti-Darwinist. I can only plead that the accusation is unfounded. Darwinism is an idea of intoxicating beauty, and yet there has been for many years a muddle at the heart of it, at least in its modern form. For the most part, we’ve safely been able to ignore that muddle because Darwin’s idea explained so much that it has kept us happily occupied at figuring out what it did explain. We’re now coming to the point, though, where what it cannot explain is coming into stark relief, making it impossible any longer to ignore the muddle.

  For example, we don’t have a good Darwinian explanation for the origin of life. Part of the reason for this is that we don’t have a good Darwinian explanation for what life is in the first place. Nor do we have a good explanation for the origin and evolution of the cornerstone of the edifice of modern Darwinism, the gene. If that weren’t enough, Darwinism is also having a rather hard time explaining what an organism is, or why life seems to tend toward “organism-like” assemblages, or as I have argued in another book, why living things are actually (not apparently) well-designed. For the longest time, we’ve been able to fudge these problems, carried along on the faith that, to paraphrase the punch line of an old joke, there had to be a pony in there somewhere.* But the dread possibility is beginning to rear its head: what if the pony isn’t there?

  The problem for modern Darwinism is, I argue, that we lack a coherent theory of the core Darwinian concept of adaptation. As the conventional story goes, adaptation is the “good fit” between organism and environment, that suite of behaviors, attributes, phenotypes, whatever we wish to call them, that enable “fit” organisms to be more fecund than organisms that are not so “fit.” This idea, so brilliantly simple that Thomas Huxley rebuked himself for his own stupidity at not seeing it before his friend Darwin pointed it out,* is the core operating principle, pure and simple, of the theory of evolution by natural selection. If adaptation does not work, natural selection does not work, period.

  It follows that we should therefore have a pretty good idea, commensurate with our confidence, of what adaptation is. In reality, our conception of adaptation rests on a very shaky foundation. To illustrate, consider how a recent (and admirable) textbook of evolution put it: “Adaptations are the products of natural selection, while adaptation is the response to natural selection.”1 This demonstrates, in one short and elegantly crafted sentence, The Problem: our current conception of this core evolutionary idea is essentially meaningless. What is adaptation? The product of natural selection! What is natural selection? The outcome of adaptation!

  This type of reasoning is known formally as a tautology, which ordinarily is ranked as one of the elementary logical fallacies, an argument wherein the conclusion is a restatement of the premise, for example, “it is what it is.” Yet there it is, resplendent on the page, as it has been on perhaps hundreds of other pages over the past century and a half. For Darwinism to make sense (and I want deeply for it to make sense), the tautology somehow needs to be resolved.

  But how? One is tempted to say that more research will clear it up eventually, given enough time, brains, and money to fund the quest—in short, to keep looking for that pony under the tree. I’m doubtful that will work, however, for the obstacle to resolving the tautology is not that we know too little—far from it—but that we aren’t thinking properly about what we do know. In short, the obstacle is largely philosophical, and the stumbling block is the frank purposefulness that is inherent in the phenomenon of adaptation.

  To see adaptation at work, which is something we physiologists spend a lot of our time doing, is to witness a phenomenon rife with purpose, intentionality, and striving. Such things do not sit well in the modern metaphysics of biology, which regards squishy things like purposefulness, intentionality, and consciousness as somehow illusory. For a biologist to treat them as something real is therefore a modern heresy, and those who advocate it suffer the fate that heretics often do: they are cast mercilessly from the altar.*

  Yet disposing of a heretic does not make the uncomfortable question go away. And the uncomfortable question is this: what if phenomena like intentionality, purpose, and design are not illusions, but are quite real—are in fact the central attributes of life? How can we have a coherent theory of life that tries to shunt these phenomena to the side? And if we don’t have a coherent theory of life, how can we have a coherent theory of evolution? This is the hard nut that has to be cracked, and this leads me to the other theme I develop throughout this book: the hammer that will crack the nut of a coherent theory of life will be the largely misunderstood, widely trivialized, but profound concept of homeostasis: what I call Biology’s Second Law.

  2

  Biology’s Second Law

  Are there scientific laws in biology, something akin to the First Law of Thermodynamics (conservation of energy) or to Newton’s First Law of Motion (conservation of momentum)? If there is any claim to Biology’s First Law, the Darwinian idea—evolution by natural selection—has a very strong one. As far as most biologists are concerned, that’s as far as it needs to go. In Darwin’s Dangerous Idea Daniel Dennett expressed this in a penetrating phrase: all problems concerning life, be they scientific, philosophical, or historical, should be etched into clear relief under Darwinism’s “universal acid.”* If this is true, then biology simply has no need for a Second Law. Of course, not all problems seem to have yielded to Darwinism’s universal acid—I mentioned some recalcitrant ones in Chapter 1 and will return to them in subsequent chapters—but let’s leave those for now and try to flesh out what I claim Biology’s Second Law should be.

  It has a handy and well-known name—homeostasis*—which is usually dryly defined as “a state of internal constancy that is maintained as a result of active regulatory processes.”1 The concept is a central one for the science of physiology, of how living things work, to borrow from one author’s pit
hy description.2 Our own body temperatures are tightly regulated, for example, and so we speak of body temperature homeostasis, literally the steady (homeo-) state (-stasis) of our body’s temperature, and the mechanisms that underlie the body’s “thermostat.” The same can be said for a myriad of other functions, such as regulation of water in the body (water homeostasis), of salts (salt homeostasis), and of the blood’s acidity (blood acid-base homeostasis).

  This rather anodyne description of homeostasis doesn’t really do the concept justice, though, because homeostasis stands today as one of the least understood and most widely trivialized concepts in modern biology. This seems at first to be a startling thing to say. If homeostasis is the foundational principle of physiology, we should have a pretty good idea of what it means. But we don’t, and the obstacle is clear: it’s mechanism. When physiologists speak of homeostasis, their reflex is to delve deeply into the delicious details of mechanism—of, say, the body’s “thermostat,” as if the body were a house controlled by a machine. In other words, to study homeostasis is to dig into the realm of the mechanic, which, by definition, is concerned primarily with machines.

  This invites the question: is life in fact a machine? Spend any time with something living, and you will see instantly that the answer is both yes and no. Mechanism is at work, to be sure, fascinating mechanism in fact, and it is essential on many levels—for the sake of innate curiosity, to develop better medical therapies, to name two—that we understand life on those terms. Yet striving and desiring seem to occupy a lot of what life does. My dog strives to tear his chew toys apart into little pieces, seems to relish it, and devotes a great deal of his day to the task; how does that work? A fish strives to find shelter or lunch or love; how does that work? Even single-celled creatures will seek light or shun it. What meaning should we ascribe to these desires, to use a loaded word?