It cannot refute the laws of mathematics, which pit exponential
population
growth against finite, or at best arithmetically increasing, resources.
Steven-Pinker-The-Blank-Slate 1
29 Similarly, natural flavors -- defined by one food scientist as "a flavor that's been derived with an out-of- date technology" -- are often chemically indistinguishable from their artificial {230} counterparts, and when they are distinguishable, sometimes the natural flavor is the more dangerous one.
When "natural" almond flavor, benzaldehyde, is derived from peach pits, it is accompanied by traces of cyanide; when it is synthesized as an "artificial flavor," it is not.
30
A blanket fear of all artificial and genetically modified foods is patently irrational on health grounds, and it could make food more expensive and hence less available to the poor. Where do these specious fears come from? Partly they arise from the carcinogen-du-jour school of journalism that uncritically reports any study showing elevated cancer rates in rats fed megadoses of chemicals. But partly they come from an intuition about living things that was first identified by the anthropologist James George Frazer in 1890 and has recently been studied in the lab by Paul Rozin, Susan Gelman, Frank Keil, Scott Atran, and other cognitive scientists. 31
People's intuitive biology begins with the concept of an invisible essence residing in living things, which gives them their form and powers. These essentialist beliefs emerge early in childhood, and in traditional cultures they dominate reasoning about plants and animals. Often the intuitions serve people well. They allow preschoolers to deduce that a raccoon that looks like a skunk will have raccoon babies, that a seed taken from an apple and planted with flowers in
? ? ? ? ? ? ? ? ? a pot will produce an apple tree, and that an animal's behavior depends on its innards, not on its appearance. They allow traditional peoples to deduce that different-looking creatures (such as a caterpillar and a butterfly) can belong to the same kind, and they impel them to extract juices and powders from living things and try them as medicines, poisons, and food supplements. They can prevent people from sickening themselves by eating things that have been in contact with infectious substances such as feces, sick people, and rotting meat. 32
But intuitive essentialism can also lead people into error. 33 Children falsely believe that a child of English-speaking parents will speak English even if brought up in a French-speaking family, and that boys will have short hair and girls will wear dresses even if they are brought up with no other member of their sex from which they can learn those habits. Traditional peoples believe in sympathetic magic, otherwise known as voodoo. They think similar-looking objects have similar powers, so that a ground-up rhinoceros horn is a cure for erectile dysfunction. And they think that animal parts can transmit their powers to anything they mingle with, so that eating or wearing a part of a fierce animal will make one fierce.
Educated Westerners should not feel too smug. Rozin has shown that we have voodoolike intuitions ourselves. Most Americans won't touch a sterilized cockroach, or even a plastic one, and won't drink juice that the roach has touched for even a fraction of a second. 34 And even Ivy League students believe that you are what you eat. They judge that a tribe that hunts turtles for their {231} meat and wild boar for their bristles will be good swimmers, and that a tribe that hunts turtles for their shells and wild boar for their meat will be tough fighters. 35 In his history of biology, Ernst Mayr showed that many biologists originally rejected the theory of natural selection because of their belief that a species was a pure type defined by an essence. They could not wrap their minds around the concept that species are populations of variable individuals and that one can blend into another over evolutionary time. 36
In this context, the fear of genetically modified foods no longer seems so strange: it is simply the standard human intuition that every living thing has an essence. Natural foods are thought to have the pure essence of the plant or animal and to carry with them the rejuvenating powers of the pastoral environment in which they grew. Genetically modified foods, or foods containing artificial additives, are thought of as being deliberately laced with a contaminant tainted by its origins in an acrid laboratory or factory. Arguments that invoke genetics, biochemistry, evolution, and risk analysis are likely to fall on deaf ears when pitted against this deep-rooted way of thinking.
Essentialist intuitions are not the only reason that perceptions of danger can be off the mark. Risk analysts have discovered to their bemusement that people's fears are often way out of line with objective hazards. Many people avoid flying, though car travel is eleven times more dangerous. They fear getting eaten by a shark, though they are four hundred times more likely to drown in their bathtub. They clamor for expensive measures to get chloroform and trichloroethylene out of drinking water, though they are hundreds of times more likely to get cancer from a daily peanut butter sandwich (since peanuts can carry a highly carcinogenic mold). 37 Some of these risks may be misestimated because they tap into our innate fears of heights, confinement, predation, and poisoning. 38 But even when people are presented with objective information about danger, they may not appreciate it because of the way the mind assesses probabilities.
A statement like "The chance of dying of botulism poisoning in a given year is . 000001" is virtually incomprehensible. For one thing, magnitudes with lots of zeroes at the beginning or end are beyond the ken of our number sense. The psychologist Paul Slovic and his colleagues found that people are unmoved by a lecture on the hazards of not wearing a seat belt which mentions that a fatal collision occurs once in every 3. 5 million person-trips. But they say they will buckle up when the odds are recalculated to show that their lifetime chance of dying in a collision is one percent. 39
The other reason for the incomprehensibility of many statistics is that the probability of a single event, such as my dying in a plane crash (as opposed to the frequency of some events relative to others, such as the proportion of all airline passengers who die in crashes), is a genuinely puzzling concept, even to mathematicians. What sense can we make of the odds offered by expert {232} bookmakers for particular events, such as that the Archbishop of Canterbury will confirm the second coming within a year (1000 to 1), that a Mr. Braham of Luton, England, will invent a perpetual motion machine (250 to 1), or that Elvis Presley is alive and well (1000 to 1)? 40 Either Elvis is alive or he isn't, so what does it mean to say that the probability that he is alive is . 001? Similarly, what should we think when aviation safety analysts tell us that on average a single landing in a commercial airliner reduces one's life expectancy by fifteen minutes? When the plane comes down, either my life expectancy will be reduced by a lot more than fifteen minutes or it won't be reduced at all. Some mathematicians say that the probability of a single event is more like a gut feeling of confidence, expressed on a scale of 0 to 1, than a meaningful mathematical quantity. 41
The mind is more comfortable in reckoning probabilities in terms of the relative frequency of remembered or imagined events. 42 That can make recent and memorable events -- a plane crash, a shark attack, an anthrax infection -- loom larger in one's worry list than more frequent and boring events, such as the car crashes and ladder falls that
? ? ? ? ? ? ? ? ? ? ? ? ? get printed beneath the fold on page B14. And it can lead risk experts to speak one language and ordinary people to hear another. In hearings for a proposed nuclear waste site, an expert might present a fault tree that lays out the conceivable sequences of events by which radioactivity might escape. For example, erosion, cracks in the bedrock, accidental drilling, or improper sealing might cause the release of radioactivity into groundwater. In turn, groundwater movement, volcanic activity, or an impact of a large meteorite might cause the release of radioactive wastes into the biosphere. Each train of events can be assigned a probability, and the aggregate probability of an accident from all the causes can be estimated. When people hear these analyses, however, they are not reassured but become more fearful than ever -- they hadn't realized there are so many ways for something to go wrong! They mentally tabulate the number of disaster scenarios, rather than mentally aggregating the probabilities of the disaster scenarios. 43
None of this implies that people are dunces or that "experts" should ram unwanted technologies down their throats. Even with a complete understanding of the risks, reasonable people might choose to forgo certain technological advances. If something is viscerally revolting, a democracy should allow people to reject it whether or not it is "rational" by some criterion that ignores our psychology. Many people would reject vegetables grown in sanitized human waste and would avoid an elevator with a glass floor, not because they believe these things are dangerous but because the thought gives them the willies. If they have the same reaction to eating genetically modified foods or living next to a nuclear power plant, they should have the option of rejecting them, too, as long as they do not try to force their preferences on others or saddle them with the costs. {233}
Also, even if technocrats provide reasonable estimates of a risk (which is itself an iffy enterprise), they cannot dictate what level of risk people ought to accept. People might object to a nuclear power plant that has a minuscule risk of a meltdown not because they overestimate the risk but because they feel that the costs of the catastrophe, no matter how remote, are too dreadful. And of course any of these tradeoffs may be unacceptable if people perceive that the benefits would go to the wealthy and powerful while they themselves absorb the risks.
Nonetheless, understanding the difference between our best science and our ancient ways of thinking can only make our individual and collective decisions better informed. It can help scientists and journalists explain a new technology in the face of the most common misunderstandings. And it can help all of us understand the technology so that we can accept or reject it on grounds that we can justify to ourselves and to others.
~
In The Wealth of Nations, Adam Smith wrote that there is "a certain propensity in human nature . . . to truck, barter, and exchange one thing for another. " The exchange of goods and favors is a human universal and may have an ancient history. In archaeological sites tens of millennia old, pretty seashells and sharp flints are found hundreds of miles from their sources, which suggests that they got there by networks of trade. 44
The anthropologist Alan Fiske has surveyed the ethnographic literature and found that virtually all human transactions fall into four patterns, each with a distinctive psychology. 45 The first is Communal Sharing: groups of
people, such as the members of a family, share things without keeping track of who gets what. The second is Authority Ranking: dominant people confiscate what they want from lower-ranking ones. But the other two types of transactions are defined by exchanges.
The most common kind of exchange is what Fiske calls Equality Matching. Two people exchange goods or favors at different times, and the traded items are identical or at least highly similar or easily comparable. The trading partners assess their debts by simple addition or subtraction and are satisfied when the favors even out. The partners feel that the exchange binds them in a relationship, and often people will consummate exchanges just to maintain it. For example, in the trading rings of the Pacific Islands, gifts circulate from chief to chief, and the original giver may eventually get his gift back. (Many Americans suspect that this is what happens to Christmas fruitcakes. ) When someone violates an Equality Matching relationship by taking a benefit without returning it in kind, the other party feels cheated and may retaliate aggressively. Equality Matching is the only mechanism of trade in most hunter- gatherer societies. Fiske notes that it is supported by a mental model of tit-for-tat reciprocity, and Leda Cosmides and John Tooby have shown that {234} this way of thinking comes easily to Americans as well. 46 It appears to be the core of our intuitive economics.
Fiske contrasts Equality Matching with a very different system called Market Pricing, the system of rents, prices, wages, and interest rates that underlies modern economies. Market Pricing relies on the mathematics of multiplication, division, fractions, and large numbers, together with the social institutions of money, credit, written contracts, and complex divisions of labor. Market Pricing is absent in hunter-gatherer societies, and we know it played no role in our evolutionary history because it relies on technologies like writing, money, and formal mathematics, which appeared only recently. Even today the exchanges carried out by Market Pricing may involve causal chains that are impossible for any individual to grasp in full. I press some keys to enter characters into this
? ? ? ? ? ? manuscript today and entitle myself to receive some groceries years from now, not because I will barter a copy of The Blank Slate to a banana grower but because of a tangled web of third and fourth and fifth parties (publishers, booksellers, truckers, commodity brokers) that I depend on without fully understanding what they do.
When people have different ideas about which of these four modes of interacting applies to a current relationship, the result can range from blank incomprehension to acute discomfort or outright hostility. Think about a dinner guest offering to pay the host for her meal, a person barking an order to a friend, or an employee helping himself to a shrimp off the boss's plate. Misunderstandings in which one person thinks of a transaction in terms of Equality Matching and another thinks in terms of Market Pricing are even more pervasive and can be even more dangerous. They tap into very different psychologies, one of them intuitive and universal, the other rarefied and learned, and clashes between them have been common in economic history.
Economists refer to "the physical fallacy": the belief that an object has a true and constant value, as opposed to being worth only what someone is willing to pay for it at a given place and time. 47 This is simply the difference between the
Equality Matching and Market Pricing mentalities. The physical fallacy may not arise when three chickens are exchanged for one knife, but when the exchanges are mediated by money, credit, and third parties, the fallacy can have ugly consequences. The belief that goods have a "just price" implies that it is avaricious to charge anything higher, and the result has been mandatory pricing schemes in medieval times, communist regimes, and many Third World countries. Such attempts to work around the law of supply and demand have usually led to waste, shortages, and black markets. Another consequence of the physical fallacy is the widespread practice of outlawing interest, which comes from the intuition that it is rapacious to demand additional money from someone who has paid back exactly what he borrowed. Of course, the only reason people borrow at one time and repay it later is that the {235} money is worth more to them at the time they borrow it than it will be at the time they repay it. So when regimes enact sweeping usury laws, people who could put money to productive use cannot get it, and everyone's standards of living go down. 48
Just as the value of something may change with time, which creates a niche for lenders who move valuable things around in time, so it may change with space, which creates a niche for middlemen who move valuable things around in space. A banana is worth more to me in a store down the street than it is in a warehouse a hundred miles away, so I am willing to pay more to the grocer than I would to the importer -- even though by "eliminating the middleman" I could pay less per banana. For similar reasons, the importer is willing to charge the grocer less than he would charge me.
But because lenders and middlemen do not cause tangible objects to come into being, their contributions are difficult to grasp, and they are often thought of as skimmers and parasites. A recurring event in human history is the outbreak of ghettoization, confiscation, expulsion, and mob violence against middlemen, often ethnic minorities who learned to specialize in the middleman niche. 49 The Jews in Europe are the most familiar example, but the expatriate Chinese, the Lebanese, the Armenians, and the Gujeratis and Chettyars of India have suffered similar histories of persecution. One economist in an unusual situation showed how the physical fallacy does not depend on any unique historical circumstance but easily arises from human psychology. He watched the entire syndrome emerge before his eyes when he spent time in a World War II prisoner-of-war camp. Every month the prisoners received identical packages from the Red Cross. A few prisoners circulated through the camp, trading and lending chocolates, cigarettes, and other commodities among prisoners who valued some items more than others or who had used up their own rations before the end of the month. The middlemen made a small profit from each transaction, and as a result they were deeply resented -- a microcosm of the tragedy of the middleman minority. The economist wrote: "[The middleman's] function, and his hard work in bringing buyer and seller together, were ignored; profits were not regarded as a reward for labour, but as the result of sharp practises. Despite the fact that his very existence was proof to the contrary, the middleman was held to be redundant. "50 The obvious cure for the tragic shortcomings of human intuition in a high- tech world is education. And this offers priorities for educational policy: to provide students with the cognitive tools that are most important for grasping the modern world and that are most unlike the cognitive tools they are born with. The perilous fallacies we have seen in this chapter, for example, would give high priority to economics, evolutionary biology, and probability and statistics in any high school or college curriculum. Unfortunately, most curricula have barely changed since medieval times, and are barely changeable, because {236} no one wants to be the philistine who seems to be saying that it is unimportant to learn a foreign language, or English literature, or trigonometry, or the classics. But no matter how valuable a subject may be, there are only twenty-four hours in a day, and a decision to teach one subject is also a decision not to teach another one. The question is not whether trigonometry is important, but whether it is more important than statistics; not whether an educated person should know the classics, but whether it is more important for an educated person to know the classics than to know elementary economics. In a world whose complexities are constantly challenging our intuitions, these tradeoffs cannot responsibly be avoided.
? ? ? ? ? ? ~
"Our nature is an illimitable space through which the intelligence moves without coming to an end," wrote the poet Wallace Stevens in 1951. 51 The limitlessness of intelligence comes from the power of a combinatorial system. Just as a few notes can combine into any melody and a few characters can combine into any printed text, a few ideas -- person, place, thing, cause, change, move, and, or, not -- can combine into an illimitable space of thoughts. 52 The ability to conceive an unlimited number of new combinations of ideas is the powerhouse of human intelligence and a key to our success as a species. Tens of thousands of years ago our ancestors conceived new sequences of actions that could drive game, extract a poison, treat an illness, or secure an alliance. The modern mind can conceive of a substance as a combination of atoms, the plan for a living thing as the combination of DNA nucleotides, and a relationship among quantities as a combination of mathematical symbols. Language, itself a combinatorial system, allows us to share these intellectual fruits.
The combinatorial powers of the human mind can help explain a paradox about the place of our species on the planet. Two hundred years ago the economist Thomas Malthus (1766-1834) called attention to two enduring features of human nature. One is that "food is necessary for the existence of man. " The other is that "the passion between the sexes is necessary and will remain nearly in its present state. " He famously deduced:
The power of population is indefinitely greater than the power in the earth to produce subsistence for man. Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetic ratio. A slight acquaintance with numbers will show the immensity of the first power in comparison with the second.
Malthus depressingly concluded that an increasing proportion of humanity would starve, and that efforts to aid them would only lead to more misery because the poor would breed children doomed to hunger in their turn. Many recent prophets of gloom reiterated his argument. In 1967 William and Paul {237} Paddock wrote a book called Famine 1975! and in 1970 the biologist Paul Ehrlich, author of The Population Bomb, predicted that sixty-five million Americans and four billion other people would starve to death in the 1980s. In 1972 a group of big thinkers known as the Club of Rome predicted that either natural resources would suffer from catastrophic declines in the ensuing decades or that the world would choke in pollutants.
The Malthusian predictions of the 1970s have been disconfirmed. Ehrlich was wrong both about the four billion victims of starvation and about declining resources. In 1980 he bet the economist Julian Simon that five strategic metals would become increasingly scarce by the end of the decade and would thus rise in price. He lost five out of five bets. The famines and shortages never happened, despite increases both in the number of people on Earth (now six billion and counting) and in the amount of energy and resources consumed by each one. 53 Horrific famines still occur, of course, but not because of a worldwide discrepancy between the number of mouths and the amount of food. The economist Amartya Sen has shown that they can almost always be traced to short-lived conditions or to political and military upheavals that prevent food from reaching the people who need it. 54
The state of our planet is a vital concern, and we need the clearest possible understanding of where the problems lie so as not to misdirect our efforts. The repeated failure of simple Malthusian thinking shows that it cannot be the best way to analyze environmental challenges. Still, Malthus's logic seems impeccable. Where did it go wrong?
The immediate problem with Malthusian prophecies is that they underestimate the effects of technological change in increasing the resources that support a comfortable life. 55 In the twentieth century food supplies increased exponentially, not linearly. Farmers grew more crops on a given plot of land. Processors transformed more of the crops into edible food. Trucks, ships, and planes got the food to more people before it spoiled or was eaten by pests. Reserves of oil and minerals increased, rather than decreased, because engineers could find more of them and figure out new ways to get at them.
Many people are reluctant to grant technology this seemingly miraculous role. A technology booster sounds too much like the earnest voiceover in a campy futuristic exhibit at the world's fair. Technology may have bought us a temporary reprieve, one might think, but it is not a source of inexhaustible magic.
It cannot refute the laws of mathematics, which pit exponential population growth against finite, or at best arithmetically increasing, resources. Optimism would seem to require a faith that the circle can be squared.
But recently the economist Paul Romer has invoked the combinatorial nature of cognitive information processing to show how the circle might be squared after all. 56 He begins by pointing out that human material existence is limited
by ideas, not by stuff. People don't need coal or copper wire or paper {238} per se; they need ways to heat their homes, communicate with other people, and store information. Those needs don't have to be satisfied by increasing the availability of physical resources. They can be satisfied by using new ideas -- recipes, designs, or techniques -- to rearrange existing resources to yield more of what we want. For example, petroleum used to be just a contaminant
? ? ? ? ? ? ? ? of water wells; then it became a source of fuel, replacing the declining supply of whale oil. Sand was once used to make glass; now it is used to make microchips and optical fiber.
Romer's second point is that ideas are what economists call "nonrival goods. " Rival goods, such as food, fuel, and tools, are made of matter and energy. If one person uses them, others cannot, as we recognize in the saying "You can't eat your cake and have it. " But ideas are made of information, which can be duplicated at negligible cost. A recipe for bread, a blueprint for a building, a technique for growing rice, a formula for a drug, a useful scientific law, or a computer program can be given away without anything being subtracted from the giver. The seemingly magical proliferation of nonrival goods has recently confronted us with new problems concerning intellectual property, as we try to adapt a legal system that was based on owning stuff to the problem of owning information -- such as musical recordings -- that can easily be shared over the Internet.
The power of nonrival goods may have been a presence throughout human evolutionary history. The anthropologists John Tooby and Irven De-Vore have argued that millions of years ago our ancestors occupied the "cognitive niche" in the world's ecosystem. By evolving mental computations that can model the causal texture of the environment, hominids could play out scenarios in their mind's eye and figure out new ways of exploiting the rocks, plants, and animals around them. Human practical intelligence may have co-evolved with language (which allows know-how to be shared at low cost) and with social cognition (which allows people to cooperate without being cheated), yielding a species that literally lives by the power of ideas.
Romer points out that the combinatorial process of creating new ideas can circumvent the logic of Malthus:
Every generation has perceived the limits to growth that finite resources and undesirable side effects would pose if no new recipes or ideas were discovered. And every generation has underestimated the potential for finding new recipes and ideas. We consistently fail to grasp how many ideas remain to be discovered. The difficulty is the same one we have with compounding. Possibilities do not add up. They multiply. 57
For example, a hundred chemical elements, combined serially four at a time and in ten different proportions, can yield 330 billion compounds. If scientists {239} evaluated them at a rate of a thousand a day, it would take them a million years to work through the possibilities. The number of ways of assembling instructions into computer programs or parts into machines is equally mind-boggling. At least in principle, the exponential power of human cognition works on the same scale as the growth of the human population, and we can resolve the paradox of the Malthusian disaster that never happened. None of this licenses complacency about our use of natural resources, of course. The fact that the space of possible ideas is staggeringly large does not mean that the solution to a given problem lies in that space or that we will find it by the time we need it. It only means that our understanding of humans' relation to the material world has to acknowledge not just our bodies and our resources but also our minds.
~
The truism that all good things come with costs as well as benefits applies in full to the combinatorial powers of the human mind. If the mind is a biological organ rather than a window onto reality, there should be truths that are literally inconceivable, and limits to how well we can ever grasp the discoveries of science.
The possibility that we might come to the end of our cognitive rope has been brought home by modern physics. We have every reason to believe that the best theories in physics are true, but they present us with a picture of reality that makes no sense to the intuitions about space, time, and matter that evolved in the brains of middle-sized primates. The strange ideas of physics -- for instance, that time came into existence with the Big Bang, that the universe is curved in the fourth dimension and possibly finite, and that a particle may act like a wave -- just make our heads hurt the more we ponder them. It's impossible to stop thinking thoughts that are literally incoherent, such as "What was it like before the Big Bang? " or "What lies beyond the edge of the universe? " or "How does the damn particle manage to pass through two slits at the same time? " Even the physicists who discovered the nature of reality claim not to understand their theories. Murray Gell-Mann described quantum mechanics as "that mysterious, confusing discipline which none of us really understands but which we know how to use. "58 Richard Feynman wrote, "I think I can safely say that no one understands quantum mechanics. . . . Do not keep asking yourself, if you can possibly avoid it, 'But how can it be like that? '. . . Nobody knows how it can be like that. "59 In another interview, he added, "If you think you understand quantum theory, you don't understand quantum theory! "60
Our intuitions about life and mind, like our intuitions about matter and space, may have run up against a strange world forged by our best science. We have seen how the concept of life as a magical spirit united with our bodies doesn't get along with our understanding of the mind as the activity of a gradually developing brain. Other intuitions about the mind find themselves just {240} as flat-footed in pursuit of the advancing frontier of cognitive neuroscience. We have every reason to believe that consciousness and decision making arise from the
? ? ? ? ? ? electrochemical activity of neural networks in the brain. But how moving molecules should throw off subjective feelings (as opposed to mere intelligent computations) and how they bring about choices that we freely make (as opposed to behavior that is caused) remain deep enigmas to our Pleistocene psyches.
These puzzles have an infuriatingly holistic quality to them. Consciousness and free will seem to suffuse the neurobiological phenomena at every level, and cannot be pinpointed to any combination or interaction among parts. The best analyses from our combinatorial intellects provide no hooks on which we can hang these strange entities, and thinkers seem condemned either to denying their existence or to wallowing in mysticism. For better or worse, our world might always contain a wisp of mystery, and our descendants might endlessly ponder the age-old conundrums of religion and philosophy, which ultimately hinge on concepts of matter and mind. 61 Ambrose Bierce's The Devil's Dictionary contains the following entry:
? ? <<
Mind, n. A mysterious form of matter secreted by the brain. Its chief activity consists in the endeavor to ascertain its own nature, the futility of the attempt being due to the fact that it has nothing but itself to know itself with.
{241} >> Chapter 14
The Many Roots of Our Suffering
? ? ? ? The first edition of Richard Dawkins's The Selfish Gene contained a foreword by the biologist who originated some of its key ideas, Robert Trivers. He closed with a flourish:
Darwinian social theory gives us a glimpse of an underlying symmetry and logic in social relationships which, when more fully comprehended by ourselves, should revitalize our political understanding and provide the intellectual support for a science and medicine of psychology. In the process it should also give us a deeper understanding of the many roots of our suffering. 1
These were arresting claims for a book on biology, but Trivers knew he was onto something. Social psychology, the science of how people behave toward one another, is often a mishmash of interesting phenomena that are "explained" by giving them fancy names. Missing is the rich deductive structure of other sciences, in which a few deep principles can generate a wealth of subtle predictions -- the kind of theory that scientists praise as "beautiful" or "elegant. " Trivers derived the first theory in social psychology that deserves to be called elegant. He showed that a deceptively simple principle -- follow the genes -- can explain the logic of each of the major kinds of human relationships: how we feel toward our parents, our children,our siblings, our lovers, our friends, and ourselves. 2 But Trivers knew that the theory did something else as well. It offered a scientific explanation for the tragedy of the human condition. "Nature is a hanging judge," goes an old saying. Many tragedies come from our physical and cognitive makeup. Our bodies are extraordinarily improbable arrangements of matter, with many ways for things to go wrong and only a few ways for things to go right. We are certain to die, and smart enough to know it. Our minds are adapted to a world that no longer exists, prone to {242} misunderstandings correctable only by arduous education, and condemned to perplexity about the deepest questions we can entertain.
But some of the most painful shocks come from the social world -- from the manipulations and betrayals of other people. According to the fable, a scorpion asked a frog to carry him across a river, reassuring the frog that he wouldn't sting him because if he did, he would drown too. Halfway across, the scorpion did sting him, and when the sinking frog asked why, the scorpion replied, "It's in my nature. " Technically speaking, a scorpion with this nature could not have evolved, but Trivers has explained why it sometimes seems as if human nature is like the fabled scorpion nature, condemned to apparently pointless conflict.
It's no mystery why organisms sometimes harm one another. Evolution has no conscience, and if one creature hurts another to benefit itself, such as by eating, parasitizing, intimidating, or cuckolding it, its descendants will come to predominate, complete with those nasty habits. All this is familiar from the vernacular sense of "Darwinian" as a synonym for "ruthless" and from Tennyson's depiction of nature as red in tooth and claw. If that were all there was to the evolution of the human condition, we would have to agree with the rock song: Life sucks, then you die.
But of course life doesn't always suck. Many creatures cooperate, nurture, and make peace, and humans in particular find comfort and joy in their families, friends, and communities. This, too, should be familiar to readers of The Selfish Gene and the other books on the evolution of altruism that have appeared in the years since. 3 There are several reasons why organisms may evolve a willingness to do good deeds. They may help other creatures while pursuing
? ? ? ? their own interests, say, when they form a herd that confuses predators or live off each other's by-products. This is called mutualism, symbiosis, or cooperation. Among humans, friends who have common tastes, hobbies, or enemies are a kind of symbiont pair. The two parents of a brood of children are an even better example. Their genes are tied up in the same package, their children, so what is good for one is good for the other, and each has an interest in keeping the other alive and healthy. These shared interests set the stage for compassionate love and marital love to evolve.
And in some cases organisms may benefit other organisms at a cost to themselves, which biologists call altruism. Altruism in this technical sense can evolve in two main ways. First, since relatives share genes, any gene that inclines an organism toward helping a relative will increase the chance of survival of a copy of itself that sits inside that relative, even if the helper sacrifices its own fitness in the generous act. Such genes will, on average, come to predominate, as long as the cost to the helper is less than the benefit to the recipient discounted by their degree of relatedness. Family love -- the cherishing of children, {243} siblings, parents, grandparents, uncles and aunts, nieces and nephews, and cousins -- can evolve. This is called nepotistic altruism.
Altruism can also evolve when organisms trade favors. One helps another by grooming, feeding, protecting, or backing him, and is helped in turn when the needs reverse. This is called reciprocal altruism, and it can evolve when the parties recognize each other, interact repeatedly, can confer a large benefit on others at small cost to themselves, keep a memory for favors offered or denied, and are impelled to reciprocate accordingly. Reciprocal altruism can evolve because cooperators do better than hermits or misanthropes. They enjoy the gains of trading their surpluses, pulling ticks out of one another's hair, saving each other from drowning or starvation, and baby-sitting each other's children. Reciprocators can also do better over the long run than the cheaters who take favors without returning them, because the reciprocators will come to recognize the cheaters and shun or punish them.
The demands of reciprocal altruism can explain why the social and moralistic emotions evolved. Sympathy and trust prompt people to extend the first favor. Gratitude and loyalty prompt them to repay favors. Guilt and shame deter them from hurting or failing to repay others. Anger and contempt prompt them to avoid or punish cheaters. And among humans, any tendency of an individual to reciprocate or cheat does not have to be witnessed firsthand but can be recounted by language. This leads to an interest in the reputation of others, transmitted by gossip and public approval or condemnation, and a concern with one's own reputation. Partnerships, friendships, alliances, and communities can emerge, cemented by these emotions and concerns.
Many people start to get nervous at this point, but the discomfort is not from the tragedies that Trivers explained. It comes instead from two misconceptions, each of which we have encountered before. First, all this talk about genes that influence behavior does not mean that we are cuckoo clocks or player pianos, mindlessly executing the dictates of DNA. The genes in question are those that endow us with the neural systems for conscience, deliberation, and will, and when we talk about the selection of such genes, we are talking about the various ways those faculties could have evolved. The error comes from the Blank Slate and the Ghost in the Machine: if one starts off thinking that our higher mental faculties are stamped in by society or inhere in a soul, then when biologists mention genetic influence the first alternatives that come to mind are puppet strings or trolley tracks. But if higher faculties, including learning, reason, and choice, are products of a nonrandom organization of the brain, there have to be genes that help do the organizing, and that raises the question of how those genes would have been selected in the course of human evolution.
The second misconception is to imagine that talk about costs and benefits {244} implies that people are Machiavellian cynics, coldly calculating the genetic advantages of befriending and marrying. To fret over this picture, or denounce it because it is ugly, is to confuse proximate and ultimate causation. People don't care about their genes; they care about happiness, love, power, respect, and other passions. The cost-benefit calculations are a metaphorical way of describing the selection of alternative genes over millennia, not a literal description of what takes place in a human brain in real time. Nothing prevents the amoral process of natural selection from evolving a brain with genuine big-hearted emotions. It is said that those who appreciate legislation and sausages should not see them being made. The same is true for human emotions.
So if love and conscience can evolve, where's the tragedy? Trivers noticed that the confluence of genetic interests that gave rise to the social emotions is only partial. Because we are not clones, or even social insects (who can share up to three-quarters of their genes), what ultimately is best for one person is not identical to what ultimately is best for another. Thus every human relationship, even the most devoted and intimate, carries the seeds of conflict. In the movie AntZ, an ant with the voice of Woody Allen complains to his psychoanalyst:
It's this whole gung-ho superorganism thing that I just can't get. I try, but I just don't get it. What is it, I'm supposed to do everything for the colony and . . . what about my needs?
The humor comes from the clash between ant psychology, which originates in a genetic system that makes workers more closely related to one another than they would be to their offspring, and human psychology, in which our
? ? genetic distinctness leads us to ask, "What about my needs? " Trivers, following on the work of William Hamilton and George Williams, did some algebra that predicts the extent to which people should ask themselves that question. 4
The rest of this chapter is about that deceptively simple algebra and how its implications overturn many conceptions of human nature. It discredits the Blank Slate, which predicts that people's regard for their fellows is determined by their "role," as if it were a part assigned arbitrarily to an actor. But it also discredits some nai? ve views of evolution that are common among people who don't believe in the Blank Slate. Most people have intuitions about the natural state of affairs. They may believe that if we acted as nature "wants" us to, families would function as harmonious units, or individuals would act for the good of the species, or people would show the true selves beneath their social masks, or, as Newt Gingrich said in 1995, the male of our species would hunt giraffes and wallow in ditches like little piglets. 5 Understanding the patterns of genetic overlap that bind and divide us can replace simplistic views of all kinds {245} with a more subtle understanding of the human condition. Indeed, it can illuminate the human condition in ways that complement the insights of artists and philosophers through the millennia.
~
The most obvious human tragedy comes from the difference between our feelings toward kin and our feelings toward non-kin, one of the deepest divides in the living world. When it comes to love and solidarity among people, the relative viscosity of blood and water is evident in everything from the clans and dynasties of traditional societies to the clogging of airports during holidays with people traveling across the world to be with their families. 6 It has also been borne out by quantitative studies. In traditional foraging societies, genetic relatives are more likely to live together, work in each other's gardens, protect each other, and adopt each other's needy or orphaned children, and are less likely to attack, feud with, and kill each other. 7 Even in modern societies, which tend to sunder ties of kinship, the more closely two people are genetically related, the more inclined they are to come to one another's aid, especially in life-or-death situations. 8
But love and solidarity are relative. To say that people are more caring toward their relatives is to say that they are more callous toward their nonrelatives. The epigraph to Robert Wright's book on evolutionary psychology is an excerpt from Graham Greene's The Power and the Glory in which the protagonist broods about his daughter: "He said, 'Oh god, help her. Damn me, I deserve it, but let her live forever. ' This was the love he should have felt for every soul in the world: all the fear and the wish to save concentrated unjustly on the one child. He began to weep. . . . He thought: This is what I should feel all the time for everyone. "
Family love indeed subverts the ideal of what we should feel for every soul in the world. Moral philosophers play with a hypothetical dilemma in which people can run through the left door of a burning building to save some number of children or through the right door to save their own child. 9 If you are a parent, ponder this question: Is there any number of children that would lead you to pick the left door? Indeed, all of us reveal our preference with our pocketbooks when we spend money on trifles for our own children (a bicycle, orthodontics, an education at a private school or university) instead of saving the lives of unrelated children in the developing world by donating the money to charity. Similarly, the practice of parents bequeathing their wealth to their children is one of the steepest impediments to an economically egalitarian society. Yet few people would allow the government to confiscate 100 percent of their estate, because most people see their children as an extension of themselves and thus as the proper beneficiaries of their lifelong striving.
Nepotism is a universal human bent and a universal scourge of large organizations. It is notorious for sapping countries led by hereditary dynasties {246} and for bogging down governments and businesses in the Third World. A recurring historic solution was to give positions of local power to people who had no family ties, such as eunuchs, celibates, slaves, or people a long way from home. 10 A more recent solution is to outlaw or regulate nepotism, though the regulations always come with tradeoffs and exceptions.
A blanket fear of all artificial and genetically modified foods is patently irrational on health grounds, and it could make food more expensive and hence less available to the poor. Where do these specious fears come from? Partly they arise from the carcinogen-du-jour school of journalism that uncritically reports any study showing elevated cancer rates in rats fed megadoses of chemicals. But partly they come from an intuition about living things that was first identified by the anthropologist James George Frazer in 1890 and has recently been studied in the lab by Paul Rozin, Susan Gelman, Frank Keil, Scott Atran, and other cognitive scientists. 31
People's intuitive biology begins with the concept of an invisible essence residing in living things, which gives them their form and powers. These essentialist beliefs emerge early in childhood, and in traditional cultures they dominate reasoning about plants and animals. Often the intuitions serve people well. They allow preschoolers to deduce that a raccoon that looks like a skunk will have raccoon babies, that a seed taken from an apple and planted with flowers in
? ? ? ? ? ? ? ? ? a pot will produce an apple tree, and that an animal's behavior depends on its innards, not on its appearance. They allow traditional peoples to deduce that different-looking creatures (such as a caterpillar and a butterfly) can belong to the same kind, and they impel them to extract juices and powders from living things and try them as medicines, poisons, and food supplements. They can prevent people from sickening themselves by eating things that have been in contact with infectious substances such as feces, sick people, and rotting meat. 32
But intuitive essentialism can also lead people into error. 33 Children falsely believe that a child of English-speaking parents will speak English even if brought up in a French-speaking family, and that boys will have short hair and girls will wear dresses even if they are brought up with no other member of their sex from which they can learn those habits. Traditional peoples believe in sympathetic magic, otherwise known as voodoo. They think similar-looking objects have similar powers, so that a ground-up rhinoceros horn is a cure for erectile dysfunction. And they think that animal parts can transmit their powers to anything they mingle with, so that eating or wearing a part of a fierce animal will make one fierce.
Educated Westerners should not feel too smug. Rozin has shown that we have voodoolike intuitions ourselves. Most Americans won't touch a sterilized cockroach, or even a plastic one, and won't drink juice that the roach has touched for even a fraction of a second. 34 And even Ivy League students believe that you are what you eat. They judge that a tribe that hunts turtles for their {231} meat and wild boar for their bristles will be good swimmers, and that a tribe that hunts turtles for their shells and wild boar for their meat will be tough fighters. 35 In his history of biology, Ernst Mayr showed that many biologists originally rejected the theory of natural selection because of their belief that a species was a pure type defined by an essence. They could not wrap their minds around the concept that species are populations of variable individuals and that one can blend into another over evolutionary time. 36
In this context, the fear of genetically modified foods no longer seems so strange: it is simply the standard human intuition that every living thing has an essence. Natural foods are thought to have the pure essence of the plant or animal and to carry with them the rejuvenating powers of the pastoral environment in which they grew. Genetically modified foods, or foods containing artificial additives, are thought of as being deliberately laced with a contaminant tainted by its origins in an acrid laboratory or factory. Arguments that invoke genetics, biochemistry, evolution, and risk analysis are likely to fall on deaf ears when pitted against this deep-rooted way of thinking.
Essentialist intuitions are not the only reason that perceptions of danger can be off the mark. Risk analysts have discovered to their bemusement that people's fears are often way out of line with objective hazards. Many people avoid flying, though car travel is eleven times more dangerous. They fear getting eaten by a shark, though they are four hundred times more likely to drown in their bathtub. They clamor for expensive measures to get chloroform and trichloroethylene out of drinking water, though they are hundreds of times more likely to get cancer from a daily peanut butter sandwich (since peanuts can carry a highly carcinogenic mold). 37 Some of these risks may be misestimated because they tap into our innate fears of heights, confinement, predation, and poisoning. 38 But even when people are presented with objective information about danger, they may not appreciate it because of the way the mind assesses probabilities.
A statement like "The chance of dying of botulism poisoning in a given year is . 000001" is virtually incomprehensible. For one thing, magnitudes with lots of zeroes at the beginning or end are beyond the ken of our number sense. The psychologist Paul Slovic and his colleagues found that people are unmoved by a lecture on the hazards of not wearing a seat belt which mentions that a fatal collision occurs once in every 3. 5 million person-trips. But they say they will buckle up when the odds are recalculated to show that their lifetime chance of dying in a collision is one percent. 39
The other reason for the incomprehensibility of many statistics is that the probability of a single event, such as my dying in a plane crash (as opposed to the frequency of some events relative to others, such as the proportion of all airline passengers who die in crashes), is a genuinely puzzling concept, even to mathematicians. What sense can we make of the odds offered by expert {232} bookmakers for particular events, such as that the Archbishop of Canterbury will confirm the second coming within a year (1000 to 1), that a Mr. Braham of Luton, England, will invent a perpetual motion machine (250 to 1), or that Elvis Presley is alive and well (1000 to 1)? 40 Either Elvis is alive or he isn't, so what does it mean to say that the probability that he is alive is . 001? Similarly, what should we think when aviation safety analysts tell us that on average a single landing in a commercial airliner reduces one's life expectancy by fifteen minutes? When the plane comes down, either my life expectancy will be reduced by a lot more than fifteen minutes or it won't be reduced at all. Some mathematicians say that the probability of a single event is more like a gut feeling of confidence, expressed on a scale of 0 to 1, than a meaningful mathematical quantity. 41
The mind is more comfortable in reckoning probabilities in terms of the relative frequency of remembered or imagined events. 42 That can make recent and memorable events -- a plane crash, a shark attack, an anthrax infection -- loom larger in one's worry list than more frequent and boring events, such as the car crashes and ladder falls that
? ? ? ? ? ? ? ? ? ? ? ? ? get printed beneath the fold on page B14. And it can lead risk experts to speak one language and ordinary people to hear another. In hearings for a proposed nuclear waste site, an expert might present a fault tree that lays out the conceivable sequences of events by which radioactivity might escape. For example, erosion, cracks in the bedrock, accidental drilling, or improper sealing might cause the release of radioactivity into groundwater. In turn, groundwater movement, volcanic activity, or an impact of a large meteorite might cause the release of radioactive wastes into the biosphere. Each train of events can be assigned a probability, and the aggregate probability of an accident from all the causes can be estimated. When people hear these analyses, however, they are not reassured but become more fearful than ever -- they hadn't realized there are so many ways for something to go wrong! They mentally tabulate the number of disaster scenarios, rather than mentally aggregating the probabilities of the disaster scenarios. 43
None of this implies that people are dunces or that "experts" should ram unwanted technologies down their throats. Even with a complete understanding of the risks, reasonable people might choose to forgo certain technological advances. If something is viscerally revolting, a democracy should allow people to reject it whether or not it is "rational" by some criterion that ignores our psychology. Many people would reject vegetables grown in sanitized human waste and would avoid an elevator with a glass floor, not because they believe these things are dangerous but because the thought gives them the willies. If they have the same reaction to eating genetically modified foods or living next to a nuclear power plant, they should have the option of rejecting them, too, as long as they do not try to force their preferences on others or saddle them with the costs. {233}
Also, even if technocrats provide reasonable estimates of a risk (which is itself an iffy enterprise), they cannot dictate what level of risk people ought to accept. People might object to a nuclear power plant that has a minuscule risk of a meltdown not because they overestimate the risk but because they feel that the costs of the catastrophe, no matter how remote, are too dreadful. And of course any of these tradeoffs may be unacceptable if people perceive that the benefits would go to the wealthy and powerful while they themselves absorb the risks.
Nonetheless, understanding the difference between our best science and our ancient ways of thinking can only make our individual and collective decisions better informed. It can help scientists and journalists explain a new technology in the face of the most common misunderstandings. And it can help all of us understand the technology so that we can accept or reject it on grounds that we can justify to ourselves and to others.
~
In The Wealth of Nations, Adam Smith wrote that there is "a certain propensity in human nature . . . to truck, barter, and exchange one thing for another. " The exchange of goods and favors is a human universal and may have an ancient history. In archaeological sites tens of millennia old, pretty seashells and sharp flints are found hundreds of miles from their sources, which suggests that they got there by networks of trade. 44
The anthropologist Alan Fiske has surveyed the ethnographic literature and found that virtually all human transactions fall into four patterns, each with a distinctive psychology. 45 The first is Communal Sharing: groups of
people, such as the members of a family, share things without keeping track of who gets what. The second is Authority Ranking: dominant people confiscate what they want from lower-ranking ones. But the other two types of transactions are defined by exchanges.
The most common kind of exchange is what Fiske calls Equality Matching. Two people exchange goods or favors at different times, and the traded items are identical or at least highly similar or easily comparable. The trading partners assess their debts by simple addition or subtraction and are satisfied when the favors even out. The partners feel that the exchange binds them in a relationship, and often people will consummate exchanges just to maintain it. For example, in the trading rings of the Pacific Islands, gifts circulate from chief to chief, and the original giver may eventually get his gift back. (Many Americans suspect that this is what happens to Christmas fruitcakes. ) When someone violates an Equality Matching relationship by taking a benefit without returning it in kind, the other party feels cheated and may retaliate aggressively. Equality Matching is the only mechanism of trade in most hunter- gatherer societies. Fiske notes that it is supported by a mental model of tit-for-tat reciprocity, and Leda Cosmides and John Tooby have shown that {234} this way of thinking comes easily to Americans as well. 46 It appears to be the core of our intuitive economics.
Fiske contrasts Equality Matching with a very different system called Market Pricing, the system of rents, prices, wages, and interest rates that underlies modern economies. Market Pricing relies on the mathematics of multiplication, division, fractions, and large numbers, together with the social institutions of money, credit, written contracts, and complex divisions of labor. Market Pricing is absent in hunter-gatherer societies, and we know it played no role in our evolutionary history because it relies on technologies like writing, money, and formal mathematics, which appeared only recently. Even today the exchanges carried out by Market Pricing may involve causal chains that are impossible for any individual to grasp in full. I press some keys to enter characters into this
? ? ? ? ? ? manuscript today and entitle myself to receive some groceries years from now, not because I will barter a copy of The Blank Slate to a banana grower but because of a tangled web of third and fourth and fifth parties (publishers, booksellers, truckers, commodity brokers) that I depend on without fully understanding what they do.
When people have different ideas about which of these four modes of interacting applies to a current relationship, the result can range from blank incomprehension to acute discomfort or outright hostility. Think about a dinner guest offering to pay the host for her meal, a person barking an order to a friend, or an employee helping himself to a shrimp off the boss's plate. Misunderstandings in which one person thinks of a transaction in terms of Equality Matching and another thinks in terms of Market Pricing are even more pervasive and can be even more dangerous. They tap into very different psychologies, one of them intuitive and universal, the other rarefied and learned, and clashes between them have been common in economic history.
Economists refer to "the physical fallacy": the belief that an object has a true and constant value, as opposed to being worth only what someone is willing to pay for it at a given place and time. 47 This is simply the difference between the
Equality Matching and Market Pricing mentalities. The physical fallacy may not arise when three chickens are exchanged for one knife, but when the exchanges are mediated by money, credit, and third parties, the fallacy can have ugly consequences. The belief that goods have a "just price" implies that it is avaricious to charge anything higher, and the result has been mandatory pricing schemes in medieval times, communist regimes, and many Third World countries. Such attempts to work around the law of supply and demand have usually led to waste, shortages, and black markets. Another consequence of the physical fallacy is the widespread practice of outlawing interest, which comes from the intuition that it is rapacious to demand additional money from someone who has paid back exactly what he borrowed. Of course, the only reason people borrow at one time and repay it later is that the {235} money is worth more to them at the time they borrow it than it will be at the time they repay it. So when regimes enact sweeping usury laws, people who could put money to productive use cannot get it, and everyone's standards of living go down. 48
Just as the value of something may change with time, which creates a niche for lenders who move valuable things around in time, so it may change with space, which creates a niche for middlemen who move valuable things around in space. A banana is worth more to me in a store down the street than it is in a warehouse a hundred miles away, so I am willing to pay more to the grocer than I would to the importer -- even though by "eliminating the middleman" I could pay less per banana. For similar reasons, the importer is willing to charge the grocer less than he would charge me.
But because lenders and middlemen do not cause tangible objects to come into being, their contributions are difficult to grasp, and they are often thought of as skimmers and parasites. A recurring event in human history is the outbreak of ghettoization, confiscation, expulsion, and mob violence against middlemen, often ethnic minorities who learned to specialize in the middleman niche. 49 The Jews in Europe are the most familiar example, but the expatriate Chinese, the Lebanese, the Armenians, and the Gujeratis and Chettyars of India have suffered similar histories of persecution. One economist in an unusual situation showed how the physical fallacy does not depend on any unique historical circumstance but easily arises from human psychology. He watched the entire syndrome emerge before his eyes when he spent time in a World War II prisoner-of-war camp. Every month the prisoners received identical packages from the Red Cross. A few prisoners circulated through the camp, trading and lending chocolates, cigarettes, and other commodities among prisoners who valued some items more than others or who had used up their own rations before the end of the month. The middlemen made a small profit from each transaction, and as a result they were deeply resented -- a microcosm of the tragedy of the middleman minority. The economist wrote: "[The middleman's] function, and his hard work in bringing buyer and seller together, were ignored; profits were not regarded as a reward for labour, but as the result of sharp practises. Despite the fact that his very existence was proof to the contrary, the middleman was held to be redundant. "50 The obvious cure for the tragic shortcomings of human intuition in a high- tech world is education. And this offers priorities for educational policy: to provide students with the cognitive tools that are most important for grasping the modern world and that are most unlike the cognitive tools they are born with. The perilous fallacies we have seen in this chapter, for example, would give high priority to economics, evolutionary biology, and probability and statistics in any high school or college curriculum. Unfortunately, most curricula have barely changed since medieval times, and are barely changeable, because {236} no one wants to be the philistine who seems to be saying that it is unimportant to learn a foreign language, or English literature, or trigonometry, or the classics. But no matter how valuable a subject may be, there are only twenty-four hours in a day, and a decision to teach one subject is also a decision not to teach another one. The question is not whether trigonometry is important, but whether it is more important than statistics; not whether an educated person should know the classics, but whether it is more important for an educated person to know the classics than to know elementary economics. In a world whose complexities are constantly challenging our intuitions, these tradeoffs cannot responsibly be avoided.
? ? ? ? ? ? ~
"Our nature is an illimitable space through which the intelligence moves without coming to an end," wrote the poet Wallace Stevens in 1951. 51 The limitlessness of intelligence comes from the power of a combinatorial system. Just as a few notes can combine into any melody and a few characters can combine into any printed text, a few ideas -- person, place, thing, cause, change, move, and, or, not -- can combine into an illimitable space of thoughts. 52 The ability to conceive an unlimited number of new combinations of ideas is the powerhouse of human intelligence and a key to our success as a species. Tens of thousands of years ago our ancestors conceived new sequences of actions that could drive game, extract a poison, treat an illness, or secure an alliance. The modern mind can conceive of a substance as a combination of atoms, the plan for a living thing as the combination of DNA nucleotides, and a relationship among quantities as a combination of mathematical symbols. Language, itself a combinatorial system, allows us to share these intellectual fruits.
The combinatorial powers of the human mind can help explain a paradox about the place of our species on the planet. Two hundred years ago the economist Thomas Malthus (1766-1834) called attention to two enduring features of human nature. One is that "food is necessary for the existence of man. " The other is that "the passion between the sexes is necessary and will remain nearly in its present state. " He famously deduced:
The power of population is indefinitely greater than the power in the earth to produce subsistence for man. Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetic ratio. A slight acquaintance with numbers will show the immensity of the first power in comparison with the second.
Malthus depressingly concluded that an increasing proportion of humanity would starve, and that efforts to aid them would only lead to more misery because the poor would breed children doomed to hunger in their turn. Many recent prophets of gloom reiterated his argument. In 1967 William and Paul {237} Paddock wrote a book called Famine 1975! and in 1970 the biologist Paul Ehrlich, author of The Population Bomb, predicted that sixty-five million Americans and four billion other people would starve to death in the 1980s. In 1972 a group of big thinkers known as the Club of Rome predicted that either natural resources would suffer from catastrophic declines in the ensuing decades or that the world would choke in pollutants.
The Malthusian predictions of the 1970s have been disconfirmed. Ehrlich was wrong both about the four billion victims of starvation and about declining resources. In 1980 he bet the economist Julian Simon that five strategic metals would become increasingly scarce by the end of the decade and would thus rise in price. He lost five out of five bets. The famines and shortages never happened, despite increases both in the number of people on Earth (now six billion and counting) and in the amount of energy and resources consumed by each one. 53 Horrific famines still occur, of course, but not because of a worldwide discrepancy between the number of mouths and the amount of food. The economist Amartya Sen has shown that they can almost always be traced to short-lived conditions or to political and military upheavals that prevent food from reaching the people who need it. 54
The state of our planet is a vital concern, and we need the clearest possible understanding of where the problems lie so as not to misdirect our efforts. The repeated failure of simple Malthusian thinking shows that it cannot be the best way to analyze environmental challenges. Still, Malthus's logic seems impeccable. Where did it go wrong?
The immediate problem with Malthusian prophecies is that they underestimate the effects of technological change in increasing the resources that support a comfortable life. 55 In the twentieth century food supplies increased exponentially, not linearly. Farmers grew more crops on a given plot of land. Processors transformed more of the crops into edible food. Trucks, ships, and planes got the food to more people before it spoiled or was eaten by pests. Reserves of oil and minerals increased, rather than decreased, because engineers could find more of them and figure out new ways to get at them.
Many people are reluctant to grant technology this seemingly miraculous role. A technology booster sounds too much like the earnest voiceover in a campy futuristic exhibit at the world's fair. Technology may have bought us a temporary reprieve, one might think, but it is not a source of inexhaustible magic.
It cannot refute the laws of mathematics, which pit exponential population growth against finite, or at best arithmetically increasing, resources. Optimism would seem to require a faith that the circle can be squared.
But recently the economist Paul Romer has invoked the combinatorial nature of cognitive information processing to show how the circle might be squared after all. 56 He begins by pointing out that human material existence is limited
by ideas, not by stuff. People don't need coal or copper wire or paper {238} per se; they need ways to heat their homes, communicate with other people, and store information. Those needs don't have to be satisfied by increasing the availability of physical resources. They can be satisfied by using new ideas -- recipes, designs, or techniques -- to rearrange existing resources to yield more of what we want. For example, petroleum used to be just a contaminant
? ? ? ? ? ? ? ? of water wells; then it became a source of fuel, replacing the declining supply of whale oil. Sand was once used to make glass; now it is used to make microchips and optical fiber.
Romer's second point is that ideas are what economists call "nonrival goods. " Rival goods, such as food, fuel, and tools, are made of matter and energy. If one person uses them, others cannot, as we recognize in the saying "You can't eat your cake and have it. " But ideas are made of information, which can be duplicated at negligible cost. A recipe for bread, a blueprint for a building, a technique for growing rice, a formula for a drug, a useful scientific law, or a computer program can be given away without anything being subtracted from the giver. The seemingly magical proliferation of nonrival goods has recently confronted us with new problems concerning intellectual property, as we try to adapt a legal system that was based on owning stuff to the problem of owning information -- such as musical recordings -- that can easily be shared over the Internet.
The power of nonrival goods may have been a presence throughout human evolutionary history. The anthropologists John Tooby and Irven De-Vore have argued that millions of years ago our ancestors occupied the "cognitive niche" in the world's ecosystem. By evolving mental computations that can model the causal texture of the environment, hominids could play out scenarios in their mind's eye and figure out new ways of exploiting the rocks, plants, and animals around them. Human practical intelligence may have co-evolved with language (which allows know-how to be shared at low cost) and with social cognition (which allows people to cooperate without being cheated), yielding a species that literally lives by the power of ideas.
Romer points out that the combinatorial process of creating new ideas can circumvent the logic of Malthus:
Every generation has perceived the limits to growth that finite resources and undesirable side effects would pose if no new recipes or ideas were discovered. And every generation has underestimated the potential for finding new recipes and ideas. We consistently fail to grasp how many ideas remain to be discovered. The difficulty is the same one we have with compounding. Possibilities do not add up. They multiply. 57
For example, a hundred chemical elements, combined serially four at a time and in ten different proportions, can yield 330 billion compounds. If scientists {239} evaluated them at a rate of a thousand a day, it would take them a million years to work through the possibilities. The number of ways of assembling instructions into computer programs or parts into machines is equally mind-boggling. At least in principle, the exponential power of human cognition works on the same scale as the growth of the human population, and we can resolve the paradox of the Malthusian disaster that never happened. None of this licenses complacency about our use of natural resources, of course. The fact that the space of possible ideas is staggeringly large does not mean that the solution to a given problem lies in that space or that we will find it by the time we need it. It only means that our understanding of humans' relation to the material world has to acknowledge not just our bodies and our resources but also our minds.
~
The truism that all good things come with costs as well as benefits applies in full to the combinatorial powers of the human mind. If the mind is a biological organ rather than a window onto reality, there should be truths that are literally inconceivable, and limits to how well we can ever grasp the discoveries of science.
The possibility that we might come to the end of our cognitive rope has been brought home by modern physics. We have every reason to believe that the best theories in physics are true, but they present us with a picture of reality that makes no sense to the intuitions about space, time, and matter that evolved in the brains of middle-sized primates. The strange ideas of physics -- for instance, that time came into existence with the Big Bang, that the universe is curved in the fourth dimension and possibly finite, and that a particle may act like a wave -- just make our heads hurt the more we ponder them. It's impossible to stop thinking thoughts that are literally incoherent, such as "What was it like before the Big Bang? " or "What lies beyond the edge of the universe? " or "How does the damn particle manage to pass through two slits at the same time? " Even the physicists who discovered the nature of reality claim not to understand their theories. Murray Gell-Mann described quantum mechanics as "that mysterious, confusing discipline which none of us really understands but which we know how to use. "58 Richard Feynman wrote, "I think I can safely say that no one understands quantum mechanics. . . . Do not keep asking yourself, if you can possibly avoid it, 'But how can it be like that? '. . . Nobody knows how it can be like that. "59 In another interview, he added, "If you think you understand quantum theory, you don't understand quantum theory! "60
Our intuitions about life and mind, like our intuitions about matter and space, may have run up against a strange world forged by our best science. We have seen how the concept of life as a magical spirit united with our bodies doesn't get along with our understanding of the mind as the activity of a gradually developing brain. Other intuitions about the mind find themselves just {240} as flat-footed in pursuit of the advancing frontier of cognitive neuroscience. We have every reason to believe that consciousness and decision making arise from the
? ? ? ? ? ? electrochemical activity of neural networks in the brain. But how moving molecules should throw off subjective feelings (as opposed to mere intelligent computations) and how they bring about choices that we freely make (as opposed to behavior that is caused) remain deep enigmas to our Pleistocene psyches.
These puzzles have an infuriatingly holistic quality to them. Consciousness and free will seem to suffuse the neurobiological phenomena at every level, and cannot be pinpointed to any combination or interaction among parts. The best analyses from our combinatorial intellects provide no hooks on which we can hang these strange entities, and thinkers seem condemned either to denying their existence or to wallowing in mysticism. For better or worse, our world might always contain a wisp of mystery, and our descendants might endlessly ponder the age-old conundrums of religion and philosophy, which ultimately hinge on concepts of matter and mind. 61 Ambrose Bierce's The Devil's Dictionary contains the following entry:
? ? <<
Mind, n. A mysterious form of matter secreted by the brain. Its chief activity consists in the endeavor to ascertain its own nature, the futility of the attempt being due to the fact that it has nothing but itself to know itself with.
{241} >> Chapter 14
The Many Roots of Our Suffering
? ? ? ? The first edition of Richard Dawkins's The Selfish Gene contained a foreword by the biologist who originated some of its key ideas, Robert Trivers. He closed with a flourish:
Darwinian social theory gives us a glimpse of an underlying symmetry and logic in social relationships which, when more fully comprehended by ourselves, should revitalize our political understanding and provide the intellectual support for a science and medicine of psychology. In the process it should also give us a deeper understanding of the many roots of our suffering. 1
These were arresting claims for a book on biology, but Trivers knew he was onto something. Social psychology, the science of how people behave toward one another, is often a mishmash of interesting phenomena that are "explained" by giving them fancy names. Missing is the rich deductive structure of other sciences, in which a few deep principles can generate a wealth of subtle predictions -- the kind of theory that scientists praise as "beautiful" or "elegant. " Trivers derived the first theory in social psychology that deserves to be called elegant. He showed that a deceptively simple principle -- follow the genes -- can explain the logic of each of the major kinds of human relationships: how we feel toward our parents, our children,our siblings, our lovers, our friends, and ourselves. 2 But Trivers knew that the theory did something else as well. It offered a scientific explanation for the tragedy of the human condition. "Nature is a hanging judge," goes an old saying. Many tragedies come from our physical and cognitive makeup. Our bodies are extraordinarily improbable arrangements of matter, with many ways for things to go wrong and only a few ways for things to go right. We are certain to die, and smart enough to know it. Our minds are adapted to a world that no longer exists, prone to {242} misunderstandings correctable only by arduous education, and condemned to perplexity about the deepest questions we can entertain.
But some of the most painful shocks come from the social world -- from the manipulations and betrayals of other people. According to the fable, a scorpion asked a frog to carry him across a river, reassuring the frog that he wouldn't sting him because if he did, he would drown too. Halfway across, the scorpion did sting him, and when the sinking frog asked why, the scorpion replied, "It's in my nature. " Technically speaking, a scorpion with this nature could not have evolved, but Trivers has explained why it sometimes seems as if human nature is like the fabled scorpion nature, condemned to apparently pointless conflict.
It's no mystery why organisms sometimes harm one another. Evolution has no conscience, and if one creature hurts another to benefit itself, such as by eating, parasitizing, intimidating, or cuckolding it, its descendants will come to predominate, complete with those nasty habits. All this is familiar from the vernacular sense of "Darwinian" as a synonym for "ruthless" and from Tennyson's depiction of nature as red in tooth and claw. If that were all there was to the evolution of the human condition, we would have to agree with the rock song: Life sucks, then you die.
But of course life doesn't always suck. Many creatures cooperate, nurture, and make peace, and humans in particular find comfort and joy in their families, friends, and communities. This, too, should be familiar to readers of The Selfish Gene and the other books on the evolution of altruism that have appeared in the years since. 3 There are several reasons why organisms may evolve a willingness to do good deeds. They may help other creatures while pursuing
? ? ? ? their own interests, say, when they form a herd that confuses predators or live off each other's by-products. This is called mutualism, symbiosis, or cooperation. Among humans, friends who have common tastes, hobbies, or enemies are a kind of symbiont pair. The two parents of a brood of children are an even better example. Their genes are tied up in the same package, their children, so what is good for one is good for the other, and each has an interest in keeping the other alive and healthy. These shared interests set the stage for compassionate love and marital love to evolve.
And in some cases organisms may benefit other organisms at a cost to themselves, which biologists call altruism. Altruism in this technical sense can evolve in two main ways. First, since relatives share genes, any gene that inclines an organism toward helping a relative will increase the chance of survival of a copy of itself that sits inside that relative, even if the helper sacrifices its own fitness in the generous act. Such genes will, on average, come to predominate, as long as the cost to the helper is less than the benefit to the recipient discounted by their degree of relatedness. Family love -- the cherishing of children, {243} siblings, parents, grandparents, uncles and aunts, nieces and nephews, and cousins -- can evolve. This is called nepotistic altruism.
Altruism can also evolve when organisms trade favors. One helps another by grooming, feeding, protecting, or backing him, and is helped in turn when the needs reverse. This is called reciprocal altruism, and it can evolve when the parties recognize each other, interact repeatedly, can confer a large benefit on others at small cost to themselves, keep a memory for favors offered or denied, and are impelled to reciprocate accordingly. Reciprocal altruism can evolve because cooperators do better than hermits or misanthropes. They enjoy the gains of trading their surpluses, pulling ticks out of one another's hair, saving each other from drowning or starvation, and baby-sitting each other's children. Reciprocators can also do better over the long run than the cheaters who take favors without returning them, because the reciprocators will come to recognize the cheaters and shun or punish them.
The demands of reciprocal altruism can explain why the social and moralistic emotions evolved. Sympathy and trust prompt people to extend the first favor. Gratitude and loyalty prompt them to repay favors. Guilt and shame deter them from hurting or failing to repay others. Anger and contempt prompt them to avoid or punish cheaters. And among humans, any tendency of an individual to reciprocate or cheat does not have to be witnessed firsthand but can be recounted by language. This leads to an interest in the reputation of others, transmitted by gossip and public approval or condemnation, and a concern with one's own reputation. Partnerships, friendships, alliances, and communities can emerge, cemented by these emotions and concerns.
Many people start to get nervous at this point, but the discomfort is not from the tragedies that Trivers explained. It comes instead from two misconceptions, each of which we have encountered before. First, all this talk about genes that influence behavior does not mean that we are cuckoo clocks or player pianos, mindlessly executing the dictates of DNA. The genes in question are those that endow us with the neural systems for conscience, deliberation, and will, and when we talk about the selection of such genes, we are talking about the various ways those faculties could have evolved. The error comes from the Blank Slate and the Ghost in the Machine: if one starts off thinking that our higher mental faculties are stamped in by society or inhere in a soul, then when biologists mention genetic influence the first alternatives that come to mind are puppet strings or trolley tracks. But if higher faculties, including learning, reason, and choice, are products of a nonrandom organization of the brain, there have to be genes that help do the organizing, and that raises the question of how those genes would have been selected in the course of human evolution.
The second misconception is to imagine that talk about costs and benefits {244} implies that people are Machiavellian cynics, coldly calculating the genetic advantages of befriending and marrying. To fret over this picture, or denounce it because it is ugly, is to confuse proximate and ultimate causation. People don't care about their genes; they care about happiness, love, power, respect, and other passions. The cost-benefit calculations are a metaphorical way of describing the selection of alternative genes over millennia, not a literal description of what takes place in a human brain in real time. Nothing prevents the amoral process of natural selection from evolving a brain with genuine big-hearted emotions. It is said that those who appreciate legislation and sausages should not see them being made. The same is true for human emotions.
So if love and conscience can evolve, where's the tragedy? Trivers noticed that the confluence of genetic interests that gave rise to the social emotions is only partial. Because we are not clones, or even social insects (who can share up to three-quarters of their genes), what ultimately is best for one person is not identical to what ultimately is best for another. Thus every human relationship, even the most devoted and intimate, carries the seeds of conflict. In the movie AntZ, an ant with the voice of Woody Allen complains to his psychoanalyst:
It's this whole gung-ho superorganism thing that I just can't get. I try, but I just don't get it. What is it, I'm supposed to do everything for the colony and . . . what about my needs?
The humor comes from the clash between ant psychology, which originates in a genetic system that makes workers more closely related to one another than they would be to their offspring, and human psychology, in which our
? ? genetic distinctness leads us to ask, "What about my needs? " Trivers, following on the work of William Hamilton and George Williams, did some algebra that predicts the extent to which people should ask themselves that question. 4
The rest of this chapter is about that deceptively simple algebra and how its implications overturn many conceptions of human nature. It discredits the Blank Slate, which predicts that people's regard for their fellows is determined by their "role," as if it were a part assigned arbitrarily to an actor. But it also discredits some nai? ve views of evolution that are common among people who don't believe in the Blank Slate. Most people have intuitions about the natural state of affairs. They may believe that if we acted as nature "wants" us to, families would function as harmonious units, or individuals would act for the good of the species, or people would show the true selves beneath their social masks, or, as Newt Gingrich said in 1995, the male of our species would hunt giraffes and wallow in ditches like little piglets. 5 Understanding the patterns of genetic overlap that bind and divide us can replace simplistic views of all kinds {245} with a more subtle understanding of the human condition. Indeed, it can illuminate the human condition in ways that complement the insights of artists and philosophers through the millennia.
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The most obvious human tragedy comes from the difference between our feelings toward kin and our feelings toward non-kin, one of the deepest divides in the living world. When it comes to love and solidarity among people, the relative viscosity of blood and water is evident in everything from the clans and dynasties of traditional societies to the clogging of airports during holidays with people traveling across the world to be with their families. 6 It has also been borne out by quantitative studies. In traditional foraging societies, genetic relatives are more likely to live together, work in each other's gardens, protect each other, and adopt each other's needy or orphaned children, and are less likely to attack, feud with, and kill each other. 7 Even in modern societies, which tend to sunder ties of kinship, the more closely two people are genetically related, the more inclined they are to come to one another's aid, especially in life-or-death situations. 8
But love and solidarity are relative. To say that people are more caring toward their relatives is to say that they are more callous toward their nonrelatives. The epigraph to Robert Wright's book on evolutionary psychology is an excerpt from Graham Greene's The Power and the Glory in which the protagonist broods about his daughter: "He said, 'Oh god, help her. Damn me, I deserve it, but let her live forever. ' This was the love he should have felt for every soul in the world: all the fear and the wish to save concentrated unjustly on the one child. He began to weep. . . . He thought: This is what I should feel all the time for everyone. "
Family love indeed subverts the ideal of what we should feel for every soul in the world. Moral philosophers play with a hypothetical dilemma in which people can run through the left door of a burning building to save some number of children or through the right door to save their own child. 9 If you are a parent, ponder this question: Is there any number of children that would lead you to pick the left door? Indeed, all of us reveal our preference with our pocketbooks when we spend money on trifles for our own children (a bicycle, orthodontics, an education at a private school or university) instead of saving the lives of unrelated children in the developing world by donating the money to charity. Similarly, the practice of parents bequeathing their wealth to their children is one of the steepest impediments to an economically egalitarian society. Yet few people would allow the government to confiscate 100 percent of their estate, because most people see their children as an extension of themselves and thus as the proper beneficiaries of their lifelong striving.
Nepotism is a universal human bent and a universal scourge of large organizations. It is notorious for sapping countries led by hereditary dynasties {246} and for bogging down governments and businesses in the Third World. A recurring historic solution was to give positions of local power to people who had no family ties, such as eunuchs, celibates, slaves, or people a long way from home. 10 A more recent solution is to outlaw or regulate nepotism, though the regulations always come with tradeoffs and exceptions.
