by Mark Pagel
Lewis and Clark were encountering just a small number of the many different cultural survival vehicles that had evolved in the interior of that vast continent. Prior to the arrival of Europeans, there were over five hundred distinct Native American languages spoken in what is now the territory of Canada and the United States, and these are just the ones that linguists and archaeologists have been able to document.
The human tendency to separate into distinct societies has given human language a geographical mosaic on which to play out its evolution, and we expect new cultures and languages to form naturally as people spread out. The puzzle is that human groups appear to do just the opposite: it is where people are most closely packed together, as in Papua New Guinea or Vanuatu, that the greatest number of different societies is found. A colored-in linguistic map of the tropics looks as though a patchwork quilt has been laid over the landscape. By comparison in the northern regions of North America, there are only a handful of societies, each one occupying a huge area, in the entire west to east expanse of that vast continent. People need to move over large areas in this sparse landscape just to eke out a living, and this tends to blend culture and language as people continually trade, marry, and talk to each other. Remarkably, it is a pattern human societies share with biological species. Where dozens of species of bats, similar numbers of small mice and rat species, and hundreds or thousands of species of insect live in the tropics, the frozen wastelands of the polar regions of North America can only support a handful of different mammal species, such as the caribou, wolf, and polar bear.
Human cultural groups have historically partitioned the landscape among themselves almost as if they were separate biological species. But why speak a different language every few miles? Why not in regions such as the tropics form one giant cooperative society? We seem confronted with the idea that human groups have had an innate tendency throughout history to divide and form into new groups, distinct from others, and just as soon as the environment will allow it. Is it to establish an identity and to protect our knowledge and wisdom from those who might eavesdrop or, worse, subvert our group? If so, it is a risky thing to do because smaller groups are more easily overrun by others, and more vulnerable to bad luck, the loss of key people, and knowledge. But if a group can split off and survive, its members will be able to compete with and maybe even displace other groups looking to use the same lands. The advantage of forming a new group is that now your offspring rather than someone else’s come to inherit the lands around you, and they, in turn, can use them to have even more children. Our tendency to form into distinct societies might have its origins in our most basic instincts to promote copies of our genes.
CULTURES RESTRICT THE FLOW OF GENES
EVEN IN our modern developed world with roads and other links, people can often differ culturally and linguistically over a few tens of miles, as any trip around the shires of England, the French Départements or the Swiss Cantons will reveal. These differences tell us that we are a species with a long-term history of staying put, or at least of not moving very far. It is easy to dismiss this as a simple consequence of a lack of mobility; but why does that lack of mobility exist? We must remember that we are the species that occupied the world, and we managed to do so before trains, motorbikes, cars, wagons, roads, or even footpaths were invented. So, our apparent lack of mobility really tells us that, historically anyway, once we get to a place we have tended to stay there, and maybe even slow the pace of others seeking to move in.
There is an ancient moor about five miles north of the city of Oxford in England, called Otmoor. The narrow road that winds around the roughly circular moor is about fourteen miles long and runs through seven villages, all of which date back more than 1,000 years, into Anglo-Saxon times: Oddington, Charlton-on-Otmoor, Fencott, Murcott, Horton-cum-Studley, Beckley, and Noke. In the 1960s, the biological anthropologist Geoffrey Harrison, working at Oxford University, became aware that the seven villages had kept detailed parish records of births, deaths, and marriages dating back at least four hundred years. Harrison and his colleagues realized that they could use these records to track the movement of people among the villages. They quickly established that there was very little mobility and that marriage was one of the few ways by which people moved to a different place on the moor. But the bigger surprise was that prior to the eighteenth century, people often did not venture any further than the neighboring village in their search for someone to marry. In fact, because there was no route directly across the swampy moor, people had been moving from village to village around it in a circular pattern for centuries.
This surprising lack of mobility is not a phenomenon confined to small villages in a rural part of England. Walking through New York City’s Little Italy and Chinatown in Manhattan, it is easy to stand in the middle of the street that divides these two communities and hear Italian spoken by third- or fourth-generation descendants of Italian immigrants on one side and Chinese spoken by third- or fourth-generation descendants of Chinese immigrants on the other. If cultures throughout our history have tended to keep to themselves, avoid each other, or even erect barriers, such as the geographical patterns might suggest, then this should be seen in our genes. Anyone can spot genetic differences between the Chinese and Italian groups, but there are more subtle differences even among people who otherwise “look” the same.
Some years ago the statistician Robert Sokal measured a large number of background genetic markers in samples of people from all over Europe. These markers do not influence how we look or feel or what we are like. They are called neutral markers, and they merely identify people who have been separated for some time. Sokal applied a method called wombling (named after the statistician W. H. Womble) to measure the rate of change in genetic markers between these different locations. If people gradually diffuse over an area such as Europe, then no boundaries of abrupt genetic difference are expected. But Sokal discovered thirty-three boundaries in Europe that separated areas of especially sharp differences in the genetic markers. Not surprisingly, most corresponded to physical barriers such as the Alps or the English Channel. But for eleven of them, there was no physical or political barrier to the movement of people. Instead, in nine of these eleven places it was language differences that kept people from mixing. It seems humans prefer to have sex with people they can talk to!
We think of Europe as one of the most crisscrossed, settled, and resettled areas of the planet, and so genes should be thoroughly mixed. But even in Europe knowing a person’s genetic profile can often place them within a hundred or so miles of their birthplace, or if not them, their parents’ birthplace. In fact, plotting measures of genetic similarity among people of European ancestry produces a pattern that resembles the shape of Europe. Clusters on the lower left of the grid are from Spain and Portugal, the United Kingdom samples fall in the upper left, with French samples in between, those from Scandinavia and Germany fill the upper right, and samples from Romania, Bulgaria, and the nations of the former Yugoslavia fill in the lower right.
If we measure large numbers of neutral genetic markers from populations around the entire world and then use them to form clusters, we get back groupings that bear a striking resemblance to what have conventionally been recognized as the major divisions of people on the planet: Europeans and Western Asians, Africans, people from the Americas, Eastern Asians, and Australasians. But this is merely a statistical statement and should not be used to say that there are “races” of people with abrupt or clear genetic boundaries between them—there are not. All of humanity shares the same genes and we can all happily and successfully interbreed. And contrary to the pronouncements of some well-known public figures right up until recently, there is not a shred of evidence that human groups differ in the genetic factors that cause intelligence or even in general cognitive abilities. But the existence of distinct clusters of genetic similarity and dissimilarity seen all over the world tell us that we are a species that has made a habit of maintaining our
differences.
CULTURES SLOW THE FLOW OF INFORMATION
FROM “OUTSIDE”
THE ENGLISH famously lost an important battle to William, Duke of Normandy, at Hastings in the year 1066. William the Conqueror’s reign and the Norman conquest of England that he brought with him carried with it many elements of the French language. French was even the official language at the English court for around three hundred years, and the effects can still be heard in the words of government like “parliament,” “legislature,” “executive,” “judicial,” “bureaucracy,” and of course “government.” But the English language, like its people, stubbornly refused to be overrun. It is true that English today boasts a large vocabulary because about half of its words derive from the Romance or Latinate languages, of which French is one. But the other half proudly shows off its Germanic ancestry, and its core vocabulary words are more likely to be of Germanic than French origin. For example, English speakers say “good” (from German gut) not bon, “mother” and “father” (from German mutter and vater) not mère and père, and “milk” (from the German milch), not lait. On the other hand, this large mixed vocabulary gives English a freedom and variety of expression other languages will not enjoy. English speakers sitting down to dinner (from the French dîner) can refer to “beef” (from the French boeuf) or “cow” from the German kuh. And there is pork and swine, mutton and sheep.
It can be revealing of our sentiments to see how cultures treat instances of traits coming in from “outside.” When cultural traits are transmitted vertically from parents to offspring or teachers to the young, no one takes much notice. But traits acquired from other cultures are far more likely to be regarded with suspicion or even indignation, the home population being seen as an unwilling and impotent victim. The French are convinced their language is now suffering the reverse of what happened to English after William the Conqueror. France, in a spasm of linguistic isolationism, now devotes a government ministry to slowing or banning what is portrayed as an overwhelming march of English and American words, customs, and phrases into the French language and culture. Phrases like le weekend or “fast food” just won’t do for this ministry. The result is that while the other nations of the world work away on their computers, the French resolutely sit at their ordinateur (and the Swedes at their dator). The British are alert and often piqued at what they perceive to be Americanisms invading their language. But one review of the English language by the Oxford English Dictionary researchers revealed that English had admitted at least 90,000 new “meanings” (being what a word refers to) over the past century, but only 5 percent were acquired from outside British culture. If change is an enemy, it resides within, but it would appear that cultures like to shoot messengers.
So sensitive are cultures to their use of language that George Bernard Shaw once purportedly remarked that Britain and America are “two nations divided by a common language.” Some attribute the quote to Oscar Wilde or even Winston Churchill, but regardless of who said it, it is not hard to find examples. Older British hotel staff might still ask visiting American guests what time they would like to be “knocked up” in the morning. An American family hosting a British visitor might be disappointed to hear their guest describing their house as “homely,” which to Americans means unprepossessing. American visitors can elicit similar reactions in their British hosts when they comment on a person’s trousers by saying “nice pants” (suggesting to the uneasy Britons that the Americans have somehow gained knowledge of their underwear). Or as so often happens in a pub, an American guest might request two drinks at the bar by holding up two fingers to the bartender—a dangerous gesture in the UK at best, but plainly rude when it is the back of your hand that faces someone.
These anecdotal accounts can be placed upon a firmer footing. If cultures routinely swap traits with other cultures, they should tend to share the most traits with those of their nearest geographical neighbors. If, on the other hand, cultures are more closed than this and tend to acquire their traits from previous generations, then they should tend to have the traits of the cultures from which they descend; that is, of their ancestral culture. Geography and ancestry are normally correlated, but measures that can separate the two show that traits related to hunting and fishing practices, family structure and kinship, are often handed down over generations rather than acquired from neighbors. Techniques and patterns of Iranian rugs and even Native American longhouse designs tend to be handed down from generation to generation rather than acquired from neighbors.
Cultures can and do acquire ideas and skills from those nearby, but neighboring societies often differ far more at a cultural level than might be expected because they resist such influences—just think of Québec and the rest of Canada, or the outpouring of cultural diversity that occurred when the Soviet Union collapsed: in Central Asia alone, Turkmenistan, Uzbekistan, Kazakhstan, Chechnya, Tajikistan, Moldova, Kyrgyzstan, and Dagestan reappeared, all differentiated by culture, ethnicity, and language. Even under the influence of close geographical neighbors, or oppressive regimes, cultures can remain stable and coherent units. Cultural evolution is not the free fair exchange of ideas it could be.
CULTURE AND THE MISSING YEARS
IF THE genetic changes that defined our species were in place by 160,000–200,000 years ago, and social learning has been the force we think, why then did it take until 60,000–70,000 years ago before we were able to leave Africa and successfully colonize the rest of the globe? These are sometimes called the missing years for modern humans, and so staggering is the space of time for a species not to make use of its full capabilities that many authors suggest there was a very late genetic change, perhaps even as late as 40,000 years ago, that finally made us “fully” human. Forty thousand years ago is identified as the likely candidate time period because this was the time of a great flowering of human cultural innovations, including ornamentation and painting, but also tools and other aspects of what archaeologists call “material culture,” or the things we made that leave a trace in the archaeological record—for example, fine hand axes, small and complicated blades, art and decoration and arrowheads.
But such a late genetic change is unlikely since it implies that the change occurred after modern humans had left Africa. Then to explain how all modern humans came to have the same capabilities requires awkward scenarios in which, for example, some genetically superior group arises perhaps 40,000 years ago in Europe, or Asia Minor, or Australia, or New Guinea, and then resettles the entire world; or worse, that they don’t, implying some groups are inferior to others. Another suggestion is that the same mysterious late genetic change occurred repeatedly in separate groups, at all the different places in the world we were to be found at that time. Neither of these scenarios is correct. The genetic evidence shows that we all trace our ancestry back to African populations that lived probably 60,000 to 80,000 years ago, not to some more recently inhabited part of the world where a supposedly superior group arose.
Instead, our missing years might be the product of a phenomenon known as random drift that can cause small populations to lose information, and thereby slowed the pace of cultural evolution early in our history. In small populations, chance or random events from one generation to the next can strongly influence whether something or someone survives. This can slow the rate at which they can adapt if the effects of drift oppose useful changes. Its consequences can be worked out precisely using mathematical arguments, but the idea readily surrenders to a verbal one. Imagine you live in a small island tribe of around fifty people and there are five among you who carry a gene that improves celestial navigational skills. I do not suggest that there are genes for celestial navigation, but if you have ever tried to use the nighttime stars to navigate, as the Polynesians did to dramatic effect in occupying the Pacific, you will recognize that any genetic differences among people that made some better at this than others would have been strongly favored. Suppose now that all five of these people set out in a larg
e boat on a seagoing journey, and during that journey a terrible storm blows up and they all drown at sea. In one stroke of bad luck this valuable gene has been driven to extinction, at least in this society.
But now, instead of fifty people in the tribe, let’s consider there are five hundred, and that as before 10 percent of the people or fifty carry this special gene. It would take a particularly extreme spell of bad luck—or perhaps a very big boat—for all fifty of these people to find themselves in the same boat on the same stormy night. There is no reason to restrict the argument to genes. In a small group, ideas, technologies, and skills can easily be lost owing to the effects of random drift. The reasons could be bad luck, or perhaps there are not enough models for others to imitate, key people might die, there are fewer people to come up with new ideas, and fewer people to correct others’ mistakes. We must also bear in mind that learning by watching and imitation is difficult, and so knowledge and skills are prone to drifting away from their starting points. Most of the time when you try to imitate someone doing something complicated, you get the task or the behavior wrong the first time around: just watch someone fly-fishing or hitting a golf ball and then try to repeat the action. Now imagine someone is trying to learn that same skill by watching you.
In his book Guns, Germs, and Steel, Jared Diamond describes how isolation and small population sizes can even cause societies to lose traits directly related to survival and prosperity. Diamond tells us how when Europeans first landed on Tasmania in the eighteenth century, they sent back descriptions of a culture that had lost many of the technologies originally taken there from the Australian mainland. People had reached Tasmania by 34,000 years ago but became cut off from mainland Australia when sea levels began to rise around 24,000 years ago. By the time the European explorers arrived tens of thousands of years later, the Tasmanians had no bone tools, no fishhooks, no hafted tools or spears, and no spear throwers. They had even lost their appetite for fish! Having lost bone tools they could not sew clothes. They had resorted—as did the Tierra del Fuegians of South America—to smearing their bodies with seal or other marine mammal body fat to preserve their own body heat.
