Lawyers have a stock Latin phrase, cui bono?, which means âWho benefits from this?,â 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 donât 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 donât 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 catâs 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 fearlessâand hence much more likely to be eaten by any cat in the vicinity! Cui bono? The benefit is to the fitnessâthe reproductive successâof 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 ârecognizeâ 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 isâor used to beâa 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. Forgetâfor the momentâabout 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 François Jacob once quipped that the dream of every cell is to become two cells. Every time this fission happens, a complete copy of the cellâs 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?4 This 50 percent reduction (from the geneâs 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 hostâs 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 standoffâif she is healthyâin 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 genesâor, more directly, their products, in the offspringâs internal defensesâwill 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 werenât 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 alcohol, 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 spec
ies and others should discover the plants with psychoactive ingredients and develop preferential or aversive dispositions regarding them. Elephantsâand baboons and other African animalsâhave 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 elephantsâ brains that it does in ours.
It may be that the basic bargain struck between fruit trees and frugivoresâthe seed-spreading-for-sugar dealâis 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 âcleanerâ fish that groom larger fish, depending on another species, us, but not having to enter our bodies. They mayâlike a wayward cleaner fishâget 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 âmore biologicalâ 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 Trickâa move in design space that will be âdiscoveredâ 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 âinventionsâ 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.6 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 doesnât 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).7 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 surveyedâsugar, sex, alcohol, music, moneyâare 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 manyâby the Muslims in particularâbut among those who appreciate itâsuch as the Roman Catholicsâa 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 âfilthy lucre,â something to be enjoyed only for what it can provide in the way of more worthy things of value, things with âintrinsicâ value.8 As the old song says, not entirely convincingly, the best things in life are free. Is this because money is âartificialâ and the others are all ânaturalâ? 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 âintrinsicâ value is the capacity of something to provoke a preference response in the brain quite directly. Pain is âintrinsically bad,â but this negative valence is just as dependent on an evolutionary rationale as the âintrinsic goodnessâ 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.9 Biology insists on delving beneath the surface of âintrinsicâ 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 isâor once wasâreally instrumental, not intrinsic, even if we donât see it that way. A truly intrinsic value couldnât 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 âintrinsicâ 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 meanâby definitionâthat we like them without needing any ulterior reason to like them.)
3 Asking what pays for religion
But what are the benefits; why do people want religion at all? They want it because religion is the only plausible source of certain rewards for which there is a general and inexhaustible demand.
âRodney Stark and Roger Finke, Acts of Faith
Whatever else religion is as a human phenomenon, it is a hugely costly endeavor, and evolutionary biology shows that nothing so costly just happens. Any such regular expenditure of time and energy has to be balanced by something of âvalueâ obtained, and the ultimate measure of evolutionary âvalueâ is fitness: the capacity to replicate more successfully than the competition does. (This does not mean that we ought to value replication above all! It means only that nothing can evolve and persist for long in this demanding world unless it somehow provokes its own replication better than the replication of its rivals.) Since money is such a recent innovation from the perspective of evolutionary history, it is weirdly anachronistic to ask what pays for one evolved biological feature or another as if there were actual transactions and ledgers in Darwinâs countinghouse. But this metaphor nevertheless nicely captures the underlying balance of forces observed everywhere in nature, and we know of no exceptions to the rule. So, risking offense but shrugging off that risk as just one more aspect of the taboo that must be broken, I ask: what pays for religion? Abhor the language if you must, but that gives you no good reason to ignore the question. Any claim to the effect that religionâyour religion or all religionâstands above the biosphere and does not have to answer to this demand is simply bluster. It might be that God implants each human being with an immortal soul that thirsts for opportunities to
worship God. That would indeed explain the bargain struck, the exchange of human time and energy for religion. The only honest way to defend that proposition, or anything like it, is to give fair consideration to alternative theories of the persistence and popularity of religion and rule them out by showing that they are unable to account for the phenomena observed. Besides, you might want to defend the hypothesis that God set up the universe so that we would evolve to have a love of God. If so, we would want to understand how that evolution occurred.
The same sort of investigation that has unlocked the mysteries of sweetness and alcohol and sex and money can be undertaken for the many facets of religion. There was a time, not so very long ago by evolutionary standards, when there was no religion on this planet, and now there is lots of it. Why? It may have one primary evolutionary source or many, or it may defy evolutionary analysis altogether, but we wonât know until we look. Do we really need to inquire about this? Canât we just accept the obvious fact that religion is a human phenomenon and that humans are mammals, and hence products of evolution, and then leave the biological underpinnings of religion at that? People make religions but they also make automobiles and literature and sports, and surely we donât need to look deep into biological prehistory to understand the differences between a sedan, a poem, and a tennis tournament. Arenât most of the religious phenomena that need investigation cultural and socialâideological, philosophical, psychological, political, economic, historicalâand hence somehow âaboveâ the biological level?
Breaking the Spell Page 8
