Blessed be the Lord, who daily loadeth us with benefits, even the God of our salvation. Selah. –Psalm 68:19
The more we learn about the details of natural processes, the more evident it becomes that these processes are themselves creative. Nothing transcends Nature like Nature itself. –Loyal Rue
Good things don't just happen by chance. There are "strokes of luck," but sustaining a good thing isn't just luck. It might be Providence of course. It might be that God makes sure that the good thing happens and that it sustains itself when it wouldn't otherwise, without God's intervening. But any such account will have to wait its turn, for the same reason that cancer researchers are unwilling to treat unexpected remissions as just "miracles" that needn't be explored any further. What natural, nonmiraculous set of processes could produce and sustain this phenomenon that is so highly valued? The only way to take the hypothesis of miracles seriously is to eliminate the nonmiraculous alternatives.
The stinginess of Nature can be seen wherever we look, if we know what to look for. For instance, coyotes are emerging as a welcome addition to the wildlife of New England, howling eerily in the winter nights, but these beautiful, wily predators are wary of humans, and seldom seen. How can you tell their footprints in the snow from those of their cousins, domestic dogs? Even up close, it can be hard to tell the paw print of a coyote from the paw print of a similarly sized dog—a dog's claws tend to be longer, since they spend scant time digging—but even from afar, a coyote's track can be readily distinguished from a dog's—the coyote's prints fall in an uncannily straight and single-file line, with hind paws in almost perfect registration with forepaws, whereas a dog's track is typically a mess, as the dog galumphs exuberantly hither and yon, indulging every curious whim (David Brown, 2004). The dog is well fed and knows it will get its supper no matter what, whereas the coyote is on a very tight budget and needs to conserve every calorie for the job at hand: self-preservation. Its methods of locomotion have been ruthlessly optimized for efficiency. But, then, what explains the pack's characteristic howling? What good accrues to the coyote from that conspicuous expenditure of energy? Hardly a low profile. Doesn't it serve to scare away their supper and draw their presence to the attention of their own predators? Such costs would not be lightly recouped, one would think. These are good questions. Biologists are working on them, and even though they don't yet have definitive answers, they are surely right to seek them. Any such pattern of conspicuous outlay demands an accounting.
Consider, for instance, the huge outlay of human effort devoted worldwide to sugar: not just the planting and harvesting of sugarcane and sugar beets, and the refining and transporting of the basic product, but the larger surrounding world of manufacturing candy, publishing cookbooks full of dessert recipes, advertising soft drinks and chocolates, commercializing Halloween, as well as the counterbalancing parts of the system: obesity clinics, government-sponsored research on the epidemic of early-onset diabetes, dentists and the inclusion of fluoride in toothpaste and drinking water. Over a hundred million metric tons of sugar are produced and consumed each year. To explain the thousands of features of this huge system, which provides the lifework of millions of people and can be discerned at every level of society, we need many different scientific and historical investigations, only a small fraction of which are biological. We need to study the chemistry of sugar, the physics of crystallization and caramelization, human physiology, and the history of agriculture, but also the history of engineering, manufacturing, transportation, banking, geopolitics, advertising, and much more.
None of these sugar-related expenditures of time and energy would exist if it weren't for the bargain that was struck about fifty million years ago between plants blindly "seeking" a way of dispersing their pollinated seeds, and animals similarly seeking efficient sources of energy to fuel their own reproductive projects. There are other ways to get your seeds dispersed, such as windborne gliders and whirligigs, and each method has its associated costs and benefits. Heavy, fleshy fruits full of sugar are a high-investment strategy, but they can have a bonanza payoff: the animal not only carries away the seed, but deposits it on a suitable bit of ground wrapped in a large helping of fertilizer. The strategy almost never works—not even once in a thousand tries—but it only has to work once or twice in the lifetime of a plant for it to replace itself on the planet and keep its lineage going. This is a good example of Mother Nature's stinginess in the final accounting combined with absurd profligacy in the methods. Not one sperm in a billion accomplishes its life mission—thank goodness—but each is designed and equipped as if everything depended on its success. (Sperm are like e-mail spam, so cheap to make and deliver that a vanishingly small return rate is sufficient to underwrite the project.)
Coevolution endorsed the bargain between plant and animal, sharpening our ancestors' capacity to discriminate sugar by its "sweetness." That is, evolution provided animals with specific receptor molecules that respond to the concentration of high-energy sugars in anything they taste, and hard-wired these receptor molecules to the seeking machinery, to put it crudely. People generally say that we like some things because they are sweet, but this really puts it backward: it is more accurate to say that some things are sweet (to us) because we like them! (And we like them because our ancestors who were wired up to like them had more energy for reproduction than their less fortunately wired-up peers.) There is nothing "intrinsically sweet" (whatever that would mean) about sugar molecules, but they are intrinsically valuable to energy-needing organisms, so evolution has arranged for organisms to have a built-in and powerful preference for anything that tickles their special-purpose high-energy detectors. That is why we are born with an instinctual liking for sweets—and, in general, the sweeter the better.
Both parties—plants and animals—benefited, and the system improved itself over the eons. What paid for all the design and manufacture (of the initial plant and animal equipment) was the differential reproduction of frugivorous and omnivorous animals and edible-fruit-bearing plants. Not all plants "chose" the ediblefruit-making bargain, but those that did had to make their fruits attractive in order to compete. It all made perfectly good sense, economically; it was a rational transaction, conducted at a slowerthan-glacial pace over the eons, and of course no plant or animal had to understand any of this in order for the system to flourish. This is an example of what I call a free-floating rationale (Dennett, 1983,1995b). Blind, directionless evolutionary processes "discover" designs that work. They work because they have various features, and these features can be described and evaluated in retrospect as if they were the intended brainchildren of intelligent designers who had worked out the rationale for the design in advance. This is not controversial in the general run of cases. The lens of an eye, for instance, is exquisitely well-designed to do its job, and the engineering rationale for the details is unmistakable, but no designer ever articulated it until the eye was reverse-engineered by scientists. The economic rationality of the quid pro quo bargains of coevolution is unmistakable, but until very recently, with the advent of human trade a few millennia ago, the rationales of such good deals were never represented in any minds.
Digression: This is a sticking point for those who don't yet appreciate just how well established the theory of evolution by natural selection is. According to a recent survey, only about a quarter of the population of the United States understands that evolution is about as well established as the fact that water is H20. This embarrassing statistic requires some explanation, since other scientifically advanced nations don't show the same pattern. Could so many people be wrong? Well, there was a time not so long ago when only a small minority of Earth's inhabitants believed that it was round and that it traveled around the sun, so we know that majorities can be flat wrong. But how, in the face of so much striking confirmation and massive scientific evidence, could so many Americans disbelieve in evolution? It is simple: they have been solemnly told that the theory of evolution is false (or at least unproven) by people they trust more than they trust scientists. Here is an interesting question: who is to blame for this widespread misinforming of the population? Suppose the ministers of your faith, who are wise and good people, assure you that evolution is a false and dangerous theory. If you are a layperson, you may be innocent in taking them at their authoritative word and then passing it on, authoritatively, to your children. We all trust the experts about many things, and these are your experts. But where, then, did your ministers get this misinformation?
If they claim to have gotten it from scientists, they have been duped, since there are no reputable scientists who claim this. Not a one. There are plenty of frauds and charlatans, though. As you see, I will not mince words. What about the Scientific Creationists and Intelligent Design proponents who are so vocal and visible in well-publicized campaigns? They have all been carefully and patiently rebutted by conscientious scientists who have taken the trouble to penetrate their smoke screens of propaganda and expose both their shoddy arguments and their apparently deliberate misrepresentations and evasions. If you disagree heartily with this flat dismissal, you have two good choices to consider at this point:
- Educate yourself in evolutionary theory and its critics and see for yourself whether what I say is true before proceeding. (The endnotes to this chapter provide all the references you will need to get going, and it should take only a few months of hard work.)
- Suspend disbelief temporarily in order to learn what an evolutionist makes of religion as a natural phenomenon. (Perhaps your time and energy as a skeptic would be better spent trying to get to the heart of this evolutionist's perspective in search of a fatal flaw.)
Alternatively, you may believe that you don't need to consider the scientific evidence at all, since "the Bible says" that evolution is false, and that's all there is to it. This is a more extreme position than is sometimes recognized. Even if you believe that the Bible is the last and perfect word on every topic, you must recognize that there are people in the world who do not share your interpretation of the Bible. For instance, many take the Bible to be the Word of God but don't read it to rule out evolution, so it is just a plain everyday fact that the Bible does not speak clearly and unmistakably to all. Since that is so, the Bible is not a plausible candidate as common ground to be shared without farther discussion in a reasonable conversation. If you insist it is, you are thumbing your nose at the whole inquiry. (Good-bye, and I hope to see you back again someday.)
But isn't there an unjustified asymmetry here, with me refusing to defend my anticreationism here and now, while sending the biblical inerrantist off for not playing by the rules of rational discussion? No, because I have directed everyone to the literature that defends the dismissal of creationism against all objections, whereas the inerrantist is refusing to take on even that obligation. To be symmetrical, the inerrantist should encourage me to consult the literature, if it exists, that purports to demonstrate, against all objections, that the Bible is indeed the Word of God and that it rules out evolution. I haven't yet been directed to any such literature, and haven't found it on any Web site, but if it exists, it would indeed warrant consideration as a topic for another day and another project— just like creationism and its critics. Those readers who remain will not demand any further consideration by me of creationism and its variants, since I have told them where to find the answers I endorse, for better or for worse. End of Digression.
Lawyers have a stock Latin phrase, cui bono?, which means "Who benefits from this?," a question that is even more central in evolutionary biology than in the law (Dennett, 1995b). Any phenomenon in the living world that apparently exceeds the functional cries out for explanation. The suspicion is always that we must be missing something, since a gratuitous outlay is, in a word, uneconomical, and as the economists are forever reminding us, there is no such thing as a free lunch. We don't marvel at an animal doggedly grubbing in the earth with its nose, for we figure it is seeking its food, but if it regularly interrupts its rooting with somersaults, we want to know why. Since accidents do happen, it is always possible that some feature of a living thing that appears to be a pointless excess is just as pointless as it appears (rather than a deep and baffling ploy in some game we don't understand). But evolution is remarkably efficient at sweeping pointless accidents off the scene, so if we find a persistent pattern of expensive equipment or activity, we can be quite sure that something benefits from it in the only stocktaking that evolution honors: differential reproduction. We should cast our nets widely when hunting for the beneficiaries, since they are often elusive. Suppose you find rats that extravagantly risk their lives in the presence of cats, and ask the cui bono? question. What good accrues to these rats from this foolhardy behavior? Are they showing off to impress potential mates, or does their extravagant behavior somehow improve their access to good food sources? Conceivably, but probably you are looking in the wrong place for the beneficiary. Like the lancet fluke that has taken up residence in the strenuous ant with which I began this book, there is a parasite, Toxoplasma gondii, that can live in many mammals but needs to get into a cat's stomach to reproduce, and when it infects rats, it has the useful property of interfering with their nervous systems and making them hyperactive and relatively fearless—and hence much more likely to be eaten by any cat in the vicinity! Cui bono? The benefit is to the fitness—the reproductive success—of Toxoplasma gondii, not the rats it infects (Zimmer, 2000).
Every bargain in nature has its rationale, free-floating unless it happens to be a bargain devised by human bargainers, the only rationale-representers yet to have evolved on the planet. But a rationale can become obsolete. As the opportunities and perils in the environment change, a good bargain can lapse. It takes time for evolution to "recognize" this. Our sweet tooth is a good example. Like the coyotes, our hunter-gatherer ancestors lived on very tight energy budgets, and had to avail themselves of every practical opportunity to store away calories for emergency use. A practically insatiable appetite for sweets made good sense then. Now that we have developed methods for creating a superabundance of sugar, that insatiability has become a serious design flaw. Recognizing the evolutionary source of this glitch helps us figure out how to deal with it. Our sweet tooth is not just an accident or a pointless bug in an otherwise excellent system; it was designed to do the work it does, and if we underestimate its resourcefulness, its resistance to perturbation and suppression, our efforts to cope with it are apt to be counterproductive. There is a reason why we love sugar, and it is—or used to be—a very good reason. We may find other superannuated loves that need our attention. I mentioned music in the previous chapter, and we will eventually turn to a more detailed examination of its possible evolutionary sources, but I want to warm up first on some easier things we love. What about alcohol? What about money? What about sex? Sex presents some of the most interesting and challenging problems in evolutionary theory, because, on the face of it, sexual reproduction is a bad bargain indeed. Forget—for the moment—about our human kind of sex (sexy sex), and consider the most basic varieties of sexual reproduction in the living world: the sexual reproduction of almost all multicellular life-forms, from insects and clams to apple trees, and even many single-celled organisms. The great evolutionary biologist Francois Jacob once quipped that the dream of every cell is to become two cells. Every time this fission happens, a complete copy of the cell's genome is copied into the offspring. The parent clones itself, in other words; the resulting organism shares 100 percent of its genes. If you can make perfect genetic copies of yourself, why would you go to the expense of reproducing sexually, which involves not just finding a mate but, much more important, passing on only half of your genes to your offspring? This 50 percent reduction (from the gene's point of view) is known as the cost of meiosis (the kind of fission that occurs in sex cells, to distinguish it from the cloning fission of mitosis). Something must pay for this cost, and it must pay on delivery, not at some future date, since evolution lacks foresight and cannot approve bargains on the speculative basis of eventual return at some distant time.
Sexual reproduction is thus a costly investment that has to pay for itself in the short run. The details of theory and experiment on this topic are fascinating (see, e.g., Maynard Smith, 1978; Ridley, 1993), but for our purposes a few highlights from the currently front-running theory are most instructive: sex (in vertebrates like us, at least) pays for itself by making our offspring relatively inscrutable to the parasites we endow them with from birth. Parasites have short lifespans compared with their hosts, and typically reproduce many times during their host's lifetime. Mammals, for instance, are hosts to trillions of parasites. (Yes, right now, no matter how healthy and clean you are, there are trillions of parasites of thousands of different species inhabiting your gut, your blood, your skin, your hair, your mouth, and every other part of your body. They have been rapidly evolving to survive against the onslaught of your defenses since the day you were born.) Before a female can mature to reproductive age, her parasites evolve to fit her better than any glove. (Meanwhile, her immune system evolves to combat them, a standoff—if she is healthy—in an ongoing arms race.) If she gave birth to a clone, her parasites would leap to it and find themselves at home from the outset. They would be already optimized to their new surroundings. If instead she uses sexual reproduction to endow her offspring with a mixed set of genes (half from her mate), many of these genes—or, more directly, their products, in the offspring's internal defenses—will be alien or cryptic to the ship-jumping parasites. Instead of home sweet home, the parasites will find themselves in terra incognita. This gives the offspring a big head start in the arms race.
Could such a bargain pay for itself? That is the question at the heart of current research in evolutionary biology, and if the positive answer holds up to further scrutiny, then we will have found the ancient but ongoing source, in evolution, of the huge system of activities and products that we normally think of when we think of sex: marriage rituals and taboos against adultery, clothing and hairstyles, breath fresheners and pornography and condoms and HIV and all the rest. To explain why each and every facet of this huge complex exists, we will have to resort to many different kinds and levels of theory, not all of it biological. But none of this would exist if we weren't sexually reproducing creatures, and we need to understand the biological underpinnings first if we are to have a clear view of what is optional or mere historical accident, what is highly resistant to perturbation, what is exploitable. There are reasons why we love sex, and they are more complicated than you might think.
With alcohol, a somewhat different perspective emerges. What pays for the breweries, the vineyards and distilleries, and the massive delivery systems that bring alcoholic beverages within easy reach of almost every human being on the planet? We know that al, cohol, like nicotine, caffeine, and the active ingredients in chocolate, has quite specific effects on receptor molecules in our brains. Let us suppose that these effects are just coincidences at the outset. That some large molecules in some plants happen to be biochemically similar to large molecules that play important modulating roles in animal brains is, let us suppose, as likely as not. Evolution must always begin with an element of brute chance. But, then, it is not surprising that, over millions of years of exploratory ingestion, our species and others should discover the plants with psychoactive ingredients and develop preferential or aversive dispositions regarding them. Elephants—and baboons and other African animals-have been known to get falling-down drunk eating fermenting fruit from marula trees, and there is evidence that elephants will travel great distances to arrive at the marula trees just when their fruits ripen. It seems that the fruit ferments in their stomachs when yeast cells resident on the fruit undergo a population explosion, consuming the sugar and excreting carbon dioxide and alcohol. The alcohol happens to create the same sort of pleasurable effects in the elephants' brains that it does in ours.
It may be that the basic bargain struck between fruit trees and frugivores—the seed-spreading-for-sugar deal—is enhanced by an additional partnership of yeast and fruit tree. This would create an added attraction that pays off by enhancing the reproductive prospects of both the yeast and the trees, or it may be just an accident in the wild. In any case, another species, Homo sapiens, has closed the loop and initiated just such a coevolutionary bargain: we domesticated both the yeast and the fruit, and for thousands of years we have been artificially selecting for the varieties that best engender the effects we love. The yeast cells provide a service for which they are paid off in protection and nutrients. That means that the yeast cultures carefully husbanded by brewers, vintners, and bakers are human symbionts just as much as the E. coli bacteria that inhabit our intestines. Unlike endosymbiont bacteria, such as Toxoplasma gondii, which have to get into the bodies of both rat and cat, the yeast cells are a sort of ectosymbiont, like the "cleaner" fish that groom larger fish, depending on another species, us, but not having to enter our bodies. They may—like a wayward cleaner fish—get ingested by us more or less by accident, but it is really only their excretions that need to get inside us for them to prosper!
Now consider a strikingly different sort of good thing: money. Unlike the other goods we have considered, it is restricted (so far) to a single species, us, and its design is transmitted through culture, not genes. I will have more to say about cultural evolution in later chapters. In this introductory overview I want to point out just a few striking similarities between money and the "more biological" treasures we have just surveyed. Like eyesight and flight, money has evolved more than once,5 and hence is a compelling candidate for what I call a Good Trick—a move in design space that will be "discovered" again and again by blind evolutionary processes simply because so many different adaptive paths lead to it and thereby endorse it (Dennett, 1995b). Economists have worked out the rationale for money in some detail.
Money is clearly one of the most effective "inventions" of our clever species, but that rationale was free-floating until very recently. We used, and relied on, and valued money, and occasionally killed and died for money, long before the rationale of its value was made explicit in any minds. Money is not the only cultural invention to lack a specific inventor or author. Nobody invented language or music either. An entertaining coincidence is that an old term for money in the form of coin and paper issue is specie (from the same Latin root as species), and, as many have noted, the free-floating rationale of specie could lapse in the foreseeable future, and it could go extinct in the wake of credit cards and other forms of electronic funds transfer. Specie, like a virus, travels light, and doesn't carry its own reproductive machinery with it, but, rather, depends for the persistence of its kind on provoking a host (us) to make copies of it using our expensive reproduction machinery (printing presses, stamps and dies). Individual coins and pieces of paper money wear out over time, and unless more are made and adopted, the whole system may go extinct. (You may confirm this by trying to buy a boat with a pile of cowrie shells.) But since money is a Good Trick, expect some other species of money to take over the niche left vacant by the departing specie.
I have another, ulterior motive for bringing up money. The goods being surveyed—sugar, sex, alcohol, music, money—are all problematic because in each case we can develop an obsession, and crave too much of a good thing, but money has perhaps the worst reputation as a good thing. Alcohol is condemned by many—by the Muslims in particular—but among those who appreciate it—such as the Roman Catholics—a person who loves it in moderation is not considered ignoble or a fool. But we are all supposed to despise money as a thing in itself and value it only instrumentally. Money is "filthy lucre," something to be enjoyed only for what it can provide in the way of more worthy things of value, things with "intrinsic" value. As the old song says, not entirely convincingly, the best things in life are free. Is this because money is "artificial" and the others are all "natural"? Not likely. Is a string quartet or a single-malt whisky or a chocolate truffle any less artificial than a gold coin?
What we should make of this theme in human culture is an interesting question, about which I will say more later, but in the meantime we should note that the only anchor we have seen so far for "intrinsic" value is the capacity of something to provoke a preference response in the brain quite directly Pain is "intrinsically bad," but this negative valence is just as dependent on an evolutionary rationale as the "intrinsic goodness" of satisfied hunger. A rose by any other name would smell as sweet, no doubt, but it is also true that if poking around in rotting elephant carcases was as good for our reproductive prospects as it is for those of vultures, such a dead elephant would smell as sweet as a rose to us. Biology insists on delving beneath the surface of "intrinsic" values and asking why they exist, and any answer that is supported by the facts has the effect of showing that the value in question is—or once was—really instrumental, not intrinsic, even if we don't see it that way. A truly intrinsic value couldn't have such an explanation of course. It would be good just because it was good, not because it was good for something. A hypothesis to consider seriously, then, is that all our "intrinsic" values started out as instrumental values, and now that their original purpose has lapsed, at least in our eyes, they remain as things we like just because we like them. (That would not mean that we are wrong to like them! It would mean—by definition— that we like them without needing any ulterior reason to like them.)