How does a psychological event—an invention, an affectation, a decision to treat a certain kind of person in a certain way—turn into a sociocultural fact—a tradition, a custom, an ethos, a way of life? We should understand culture, according to the cognitive anthropologist Dan Sperber, as the epidemiology of mental representations: the spread of ideas and practices from person to person.18 Many scientists now use the mathematical tools of epidemiology (how diseases spread) or of population biology (how genes and organisms spread) to model the evolution of culture.19 They have shown how a tendency of people to adopt the innovations of other people can lead to effects that we understand using metaphors like epidemics, wildfire, snowballs, and tipping points. Individual psychology turns into collective culture.
CULTURE, THEN, IS a pool of technological and social innovations that people accumulate to help them live their lives, not a collection of arbitrary roles and symbols that happen to befall them. This idea helps explain what makes cultures different and similar. When a splinter group leaves the tribe and is cut off by an ocean, a mountain range, or a demilitarized zone, an innovation on one side of the barrier has no way of diffusing to the other side. As each group modifies its own collection of discoveries and conventions, the collections will diverge and the groups will have different cultures. Even when two groups stay within shouting distance, if their relationship has an edge of hostility they may adopt behavioral identity badges that advertise which side someone is on, further exaggerating any differences. This branching and differentiation is easily visible in the evolution of languages, perhaps the clearest example of cultural evolution. And as Darwin pointed out, it has a close parallel in the origin of species, which often arise when a population splits in two and the groups of descendants evolve in different directions.20 As with languages and species, cultures that split apart more recently tend to be more similar. The traditional cultures of Italy and France, for example, are more similar to each other than either is to the cultures of the Maoris and Hawaiians.
The psychological roots of culture also help explain why some bits of culture change and others stay put. Some collective practices have enormous inertia because they impose a high cost on the first individual who would try to change them. A switch from driving on the left to driving on the right could not begin with a daring nonconformist or a grass-roots movement but would have to be imposed from the top down (which is what happened in Sweden at 5 A.M., Sunday, September 3, 1967). Other examples are laying down your weapons when hostile neighbors are armed to the teeth, abandoning the QWERTY keyboard layout, and pointing out that the emperor is not wearing any clothes.
But traditional cultures can change, too, and more dramatically than most people realize. Preserving cultural diversity is considered a supreme virtue today, but the members of the diverse cultures don’t always see it that way. People have wants and needs, and when cultures rub shoulders, people in one culture are bound to notice when their neighbors are satisfying those desires better than they are. When they do notice, history tells us, they shamelessly borrow whatever works best. Far from being self-preserving monoliths, cultures are porous and constantly in flux. Language, once again, is a clear example. Notwithstanding the perennial lamentations of purists and the sanctions of language academies, no language is ever spoken the way it was centuries before. Just compare contemporary English with the language of Shakespeare, or the language of Shakespeare with the language of Chaucer. Many other “traditional” practices are surprisingly recent. The ancestors of the Hasidic Jews did not wear black coats and fur-lined hats in Levantine deserts, nor did the Plains Indians ride horses before the arrival of the Europeans. National cuisines, too, have shallow roots. Potatoes in Ireland, paprika in Hungary, tomatoes in Italy, hot chile peppers in India and China, and cassava in Africa come from New World plants, and were brought to their “traditional” homes in the centuries after the arrival of Columbus in the Americas.21
The idea that a culture is a tool for living can even explain the fact that first led Boas to argue the opposite, that a culture is an autonomous system of ideas. The most obvious cultural difference on the planet is that some cultures are materially more successful than others. In past centuries, cultures from Europe and Asia decimated the cultures of Africa, the Americas, Australia, and the Pacific. Even within Europe and Asia the fortunes of cultures have varied widely, some developing expansive civilizations rich in art, science, and technology, others stuck in poverty and helpless to resist conquest. What allowed small groups of Spaniards to cross the Atlantic and defeat the great empires of the Incas and Aztecs, rather than the other way around? Why didn’t African tribes colonize Europe instead of vice versa? The immediate answer is that the wealthy conquerors had better technology and a more complex political and economic organization. But that simply pushes back the question of why some cultures develop more complex ways of life than others.
Boas helped overthrow the bad racial science of the nineteenth century that attributed these disparities to differences in how far each race had biologically evolved. In its place his successors stipulated that behavior is determined by culture and that culture is autonomous from biology.22 Unfortunately, that left the dramatic differences among cultures unexplained, as if they were random outcomes of the lottery in Babylon. Indeed, the differences were not just unexplained but unmentionable, out of a fear that people would misinterpret the observation that some cultures were more technologically sophisticated than others as some kind of moral judgment that advanced societies were better than primitive ones. But no one can fail to notice that some cultures can accomplish things that all people want (like health and comfort) better than others. The dogma that cultures vary capriciously is a feeble refutation of any private opinion that some races have what it takes to develop science, technology, and government and others don’t.
But recently two scholars, working independently, have decisively shown that there is no need to invoke race to explain differences among cultures. Both arrived at that conclusion by eschewing the Standard Social Science Model, in which cultures are arbitrary symbol systems that exist apart from the minds of individual people. In his trilogy Race and Culture, Migrations and Cultures, and Conquests and Cultures, the economist Thomas Sowell explained his starting point for an analysis of cultural differences:
A culture is not a symbolic pattern, preserved like a butterfly in amber. Its place is not in a museum but in the practical activities of daily life, where it evolves under the stress of competing goals and other competing cultures. Cultures do not exist as simply static “differences” to be celebrated but compete with one another as better and worse ways of getting things done—better and worse, not from the standpoint of some observer, but from the standpoint of the peoples themselves, as they cope and aspire amid the gritty realities of life.23
The physiologist Jared Diamond is a proponent of ideas in evolutionary psychology and of consilience between the sciences and the humanities, particularly history.24 In Guns, Germs, and Steel he rejected the standard assumption that history is just one damn thing after another and tried to explain the sweep of human history over tens of thousands of years in the context of human evolution and ecology.25 Sowell and Diamond have made an authoritative case that the fates of human societies come neither from chance nor from race but from the human drive to adopt the innovations of others, combined with the vicissitudes of geography and ecology.
Diamond begins at the beginning. For most of human evolutionary history we lived as hunter-gatherers. The trappings of civilization—sedentary living, cities, a division of labor, government, professional armies, writing, metallurgy—sprang from a recent development, farming, about ten thousand years ago. Farming depends on plants and animals that can be tamed and exploited, and only a few species are suited to it. They happened to be concentrated in a few parts of the world, including the Fertile Crescent, China, and Central and South America. The first civilizations arose in those regions.
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om then on, geography was destiny. Diamond and Sowell point out that Eurasia, the world’s largest landmass, is an enormous catchment area for local innovations. Traders, sojourners, and conquerors can collect them and spread them, and people living at the crossroads can concentrate them into a hightech package. Also, Eurasia runs in an east-west direction, whereas Africa and the Americas run north-south. Crops and animals that are domesticated in one region can easily be spread to others along lines of latitude, which are also lines of similar climate. But they cannot be spread as easily along lines of longitude, where a few hundred miles can spell the difference between temperate and tropical climates. Horses domesticated in the Asian steppes, for example, could make their way westward to Europe and eastward to China, but llamas and alpacas domesticated in the Andes never made it northward to Mexico, so the Mayan and Aztec civilizations were left without pack animals. And until recently the transportation of heavy goods over long distances (and with them traders and their ideas) was possible only by water. Europe and parts of Asia are blessed by a notchy, furrowed geography with many natural harbors and navigable rivers. Africa and Australia are not.
So Eurasia conquered the world not because Eurasians are smarter but because they could best take advantage of the principle that many heads are better than one. The “culture” of any of the conquering nations of Europe, such as Britain, is in fact a greatest-hits collection of inventions assembled across thousands of miles and years. The collection is made up of cereal crops and alphabetic writing from the Middle East, gunpowder and paper from China, domesticated horses from Ukraine, and many others. But the necessarily insular cultures of Australia, Africa, and the Americas had to make do with a few homegrown technologies, and as a result they were no match for their pluralistic conquerors. Even within Eurasia and (later) the Americas, cultures that were isolated by mountainous geography—for example, in the Appalachians, the Balkans, and the Scottish highlands—remained backward for centuries in comparison with the vast network of people around them.
The extreme case, Diamond points out, is Tasmania. The Tasmanians, who were nearly exterminated by Europeans in the nineteenth century, were the most technologically primitive people in recorded history. Unlike the Aborigines on the Australian mainland, the Tasmanians had no way of making fire, no boomerangs or spear throwers, no specialized stone tools, no axes with handles, no canoes, no sewing needles, and no ability to fish. Amazingly, the archaeological record shows that their ancestors from the Australian mainland had arrived with these technologies ten thousand years before. But then the land bridge connecting Tasmania to the mainland was submerged and the island was cut off from the rest of the world. Diamond speculates that any technology can be lost from a culture at some point in its history. Perhaps a raw material came to be in short supply and people stopped making the products that depended on it. Perhaps all the skilled artisans in a generation were killed by a freak storm. Perhaps some prehistoric Luddite or ayatollah imposed a taboo on the practice for one inane reason or another. Whenever this happens in a culture that rubs up against other ones, the lost technology can eventually be reacquired as the people clamor for the higher standard of living enjoyed by their neighbors. But in lonely Tasmania, people would have had to reinvent the proverbial wheel every time it was lost, and so their standard of living ratcheted downward.
The ultimate irony of the Standard Social Science Model is that it failed to accomplish the very goal that brought it into being: explaining the different fortunes of human societies without invoking race. The best explanation today is thoroughly cultural, but it depends on seeing a culture as a product of human desires rather than as a shaper of them.
HISTORY AND CULTURE, then, can be grounded in psychology, which can be grounded in computation, neuroscience, genetics, and evolution. But this kind of talk sets off alarms in the minds of many nonscientists. They fear that consilience is a smokescreen for a hostile takeover of the humanities, arts, and social sciences by philistines in white coats. The richness of their subject matter would be dumbed down into a generic palaver about neurons, genes, and evolutionary urges. This scenario is often called “reductionism,” and I will conclude the chapter by showing why consilience does not call for it.
Reductionism, like cholesterol, comes in good and bad forms. Bad reductionism—also called “greedy reductionism” or “destructive reductionism”—consists of trying to explain a phenomenon in terms of its smallest or simplest constituents. Greedy reductionism is not a straw man. I know several scientists who believe (or at least say to granting agencies) that we will make break-throughs in education, conflict resolution, and other social concerns by studying the biophysics of neural membranes or the molecular structure of the synapse. But greedy reductionism is far from the majority view, and it is easy to show why it is wrong. As the philosopher Hilary Putnam has pointed out, even the simple fact that a square peg won’t fit into a round hole cannot be explained in terms of molecules and atoms but only at a higher level of analysis involving rigidity (regardless of what makes the peg rigid) and geometry.26 And if anyone really thought that sociology or literature or history could be replaced by biology, why stop there? Biology could in turn be ground up into chemistry, and chemistry into physics, leaving one struggling to explain the causes of World War I in terms of electrons and quarks. Even if World War I consisted of nothing but a very, very large number of quarks in a very, very complicated pattern of motion, no insight is gained by describing it that way.
Good reductionism (also called hierarchical reductionism) consists not of replacing one field of knowledge with another but of connecting or unifying them. The building blocks used by one field are put under a microscope by another. The black boxes get opened; the promissory notes get cashed. A geographer might explain why the coastline of Africa fits into the coastline of the Americas by saying that the landmasses were once adjacent but sat on different plates, which drifted apart. The question of why the plates move gets passed on to the geologists, who appeal to an upwelling of magma that pushes them apart. As for how the magma got so hot, they call in the physicists to explain the reactions in the Earth’s core and mantle. None of the scientists is dispensable. An isolated geographer would have to invoke magic to move the continents, and an isolated physicist could not have predicted the shape of South America.
So, too, for the bridge between biology and culture. The big thinkers in the sciences of human nature have been adamant that mental life has to be understood at several levels of analysis, not just the lowest one. The linguist Noam Chomsky, the computational neuroscientist David Marr, and the ethologist Niko Tinbergen have independently marked out a set of levels of analysis for understanding a faculty of the mind. These levels include its function (what it accomplishes in an ultimate, evolutionary sense); its real-time operation (how it works proximately, from moment to moment); how it is implemented in neural tissue; how it develops in the individual; and how it evolved in the species.27 For example, language is based on a combinatorial grammar designed to communicate an unlimited number of thoughts. It is utilized by people in real time via an interplay of memory lookup and rule application. It is implemented in a network of regions in the center of the left cerebral hemisphere that must coordinate memory, planning, word meaning, and grammar. It develops in the first three years of life in a sequence from babbling to words to word combinations, including errors in which rules may be overapplied. It evolved through modifications of a vocal tract and brain circuitry that had other uses in earlier primates, because the modifications allowed our ancestors to prosper in a socially interconnected, knowledge-rich lifestyle. None of these levels can be replaced by any of the others, but none can be fully understood in isolation from the others.
Chomsky distinguishes all of these from yet another level of analysis (one that he himself has little use for but that other language scholars invoke). The vantage points I just mentioned treat language as an internal, individual entity, such as the knowledge of Canadian Engl
ish that I possess in my head. But language can also be understood as an external entity: the “English language” as a whole, with its fifteen-hundred-year history, its countless dialects and hybrids spanning the globe, its half a million words in the Oxford English Dictionary. An external language is an abstraction that pools the internal languages of hundreds of millions of people living in different places and times. It could not exist without the internal languages in the minds of real humans conversing with one another, but it cannot be reduced to what any of them knows either. For example, the statement “English has a larger vocabulary than Japanese” could be true even if no English speaker has a larger vocabulary than any Japanese speaker.
The English language was shaped by broad historical events that did not take place inside a single head. They include the Scandinavian and Norman invasions in medieval times, which infected it with non-Anglo-Saxon words; the Great Vowel Shift of the fifteenth century, which scrambled the pronunciation of the long vowels and left its spelling system an irregular mess; the expansion of the British Empire, which budded off a variety of Englishes (American, Australian, Singaporean); and the development of global electronic media, which may rehomogenize the language as we all read the same web pages and watch the same television shows.