Why is diabetes low in Europeans?
Diabetologists used to point to Pimas and Nauruans as the glaring exceptions of high diabetes prevalence, standing out from a world in which the relatively low diabetes prevalence of Europeans was taken as the norm. But the information that has become available in recent decades shows that, instead, Europeans are the exception in their low prevalence, contrasting with the high prevalence reached by Westernized populations of everyone else. Pimas and Nauruans are “merely” the highest of that normal high prevalence, already approached closely by some Aboriginal Australians and New Guinean groups. For every well-studied large non-European population grouping, we now know of some Westernized subgroup with a prevalence above 11%, usually above 15%: Native Americans, North Africans, sub-Saharan Black Africans, Middle Easterners, Indians, East Asians, New Guineans, Aboriginal Australians, Micronesians, and Polynesians. Compared to that norm, Europeans, and overseas Europeans in Australia, Canada, New Zealand, and the U.S., are unique among the modern world’s populations in their relatively low prevalence. All 41 national European values for the prevalence of diabetes (Table 11.1, first row) fall between 2% and 10%, with a mean value of only 6%.
That’s astonishing when one reflects that Europeans in Europe itself and overseas are the world’s richest and best-fed people, and the originators of the Western lifestyle. We refer to our indolent, obese, supermarket way of life as Western precisely because it arose first among Europeans and white Americans and is only now spreading to other peoples. How can we account for this paradox? Why don’t Europeans now have the highest, rather than the lowest, prevalence of diabetes?
Several experts in the study of diabetes have suggested to me informally that perhaps Europeans traditionally had little exposure to famine, so that they would have undergone little selection for a thrifty genotype. Actually, though, history provides abundant documentation of famines that caused widespread severe mortality in medieval and Renaissance Europe and earlier. Those repeated famines should have selected for thrifty genes in Europe, just as everywhere else. Instead, a more promising hypothesis is based on Europe’s recent food history since the Renaissance. The periodic widespread and prolonged famines that used to rack Europe, like the rest of the world, disappeared between about 1650 and 1900 at different times in different parts of Europe, beginning in the late 1600s in Britain and the Netherlands, and continuing into the late 1800s in southern France and southern Italy. With one famous exception, Europe’s famines were ended by a combination of four factors: increasingly efficient state intervention that rapidly redistributed surplus grain to famine areas; increasingly efficient food transport by land and especially by sea; increasingly diversified European agriculture after Columbus’s voyage of AD 1492, thanks to European voyagers bringing back many New World crops (such as potatoes and corn); and, finally, Europe’s reliance not on irrigation agriculture (as in many populous areas of the world outside Europe) but instead on rain agriculture, which reduced the risk of a crop failure too widespread to be solved by food transport within Europe.
The famous exception to the end of Europe’s famines was of course the Irish potato famine of the 1840s. Actually, that was the exception that proved the rule, by illustrating what happened even in Europe when the first three above-mentioned factors ending famines elsewhere in Europe didn’t operate. The Irish potato famine was due to a disease of a single strain of potato in an agricultural economy that was unusual in Europe in its reliance on that single crop. The famine occurred on an island (Ireland) governed by an ethnically different state centered on another island (Britain) and notorious for the inefficiency or lack of motivation of its response to the Irish famine.
These facts of Europe’s food history lead me to offer the following speculation. Several centuries before the advent of modern medicine, Europeans, like modern Nauruans, may have undergone an epidemic of diabetes that resulted from the new reliability of adequate food supplies, and that eliminated most diabetes-prone bearers of the thrifty genotype, leaving Europe with its low prevalence of diabetes today. Those gene-bearers may have been undergoing elimination in Europe for centuries, as a result of many infants of diabetic mothers dying at birth, diabetic adults dying younger than other adults, and children and grandchildren of those diabetic adults dying of neglect or reduced material support. However, there would have been big differences between that postulated cryptic earlier European epidemic and the well-documented modern epidemics among Nauruans and so many other peoples today. In the modern epidemics, abundant and continually reliable food arrived suddenly—within a decade for Nauruans, and within just a month for Yemenite Jews. The results were sharply peaked surges in diabetes’s prevalence to 20%–50% that have been occurring right under the eyes of modern diabetologists. Those increases will probably wane quickly (as already observed among Nauruans), as individuals with a thrifty genotype become eliminated by natural selection within a mere generation or two. In contrast, Europe’s food abundance increased gradually over the course of several centuries. The result would have been an imperceptibly slow rise in diabetes prevalence in Europe, between the 1400s and the 1700s, long before there were any diabetologists to take note. In effect, Pimas, Nauruans, Wanigelas, educated urban Indians, and citizens of wealthy oil-producing Arab nations are telescoping into a single generation the lifestyle changes and consequent rise and fall of diabetes that unfolded over the course of many centuries in Europe.
A possible victim of this cryptic epidemic of diabetes that I postulate in Europe was the composer Johann Sebastian Bach (born in 1685, died in 1750). While Bach’s medical history is too poorly documented to permit certainty as to the cause of his death, the corpulence of his face and hands in the sole authenticated portrait of him (Plate 28), the accounts of deteriorating vision in his later years, and the obvious deterioration of his handwriting possibly secondary to his failing vision and/or nerve damage are consistent with a diagnosis of diabetes. The disease certainly occurred in Germany during Bach’s lifetime, being known there as honigsüsse Harnruhr (“honey-sweet urine disease”).
The future of non-communicable diseases
In this chapter I’ve discussed just two among the many currently exploding non-communicable diseases (NCDs) linked to the Western lifestyle: hypertension and its consequences, and Type-2 diabetes. Other major NCDs that I haven’t had space to discuss, but that S. Boyd Eaton, Melvin Konner, and Marjorie Shostak do discuss, include coronary artery disease and other heart diseases, arteriosclerosis, peripheral vascular diseases, many kidney diseases, gout, and many cancers including lung, stomach, breast, and prostate cancer. Within the Western lifestyle I’ve discussed only some risk factors—especially salt, sugar, high calorie intake, obesity, and sedentariness. Other important risk factors that I have mentioned only briefly include smoking, high alcohol consumption, cholesterol, triglycerides, saturated fats, and trans fats.
We’ve seen that NCDs are overwhelmingly the leading causes of death in Westernized societies, to which most readers of this book belong. Nor is it the case that you’ll have a wonderful carefree healthy life until you suddenly drop dead of an NCD at age 78 to 81 (the average lifespan in long-lived Western societies): NCDs are also major causes of declining health and decreased quality of life for years or decades before they eventually kill you. But the same NCDs are virtually non-existent in traditional societies. What clearer proof could there be that we have much to learn, of life-and-death value, from traditional societies? However, what they have to teach us is not a simple matter of just “live traditionally.” There are many aspects of traditional life that we emphatically don’t want to emulate, such as cycles of violence, frequent risk of starvation, and short lifespans resulting from infectious diseases. We need to figure out which specific components of traditional lifestyles are the ones protecting those living them against NCDs. Some of those desirable components are already obvious (e.g., exercise repeatedly, reduce your sugar intake), while others are not obvious and are
still being debated (e.g., optimal levels of dietary fat).
The current epidemic of NCDs will get much worse before it gets better. Sadly, it has already reached its peak in Pimas and Nauruans. Of special concern now are populous countries with rapidly rising standards of living. The epidemic may be closest to reaching its peak in wealthy Arab oil countries, further short of its peak in North Africa, and under way but still due to become much worse in China and India. Other populous countries in which the epidemic is well launched include Bangladesh, Brazil, Egypt, Indonesia, Iran, Mexico, Pakistan, the Philippines, Russia, South Africa, and Turkey. Countries with lower populations in which the epidemic is also under way include all countries of Latin America and Southeast Asia. It is just beginning among the not-quite 1 billion people of sub-Saharan Africa. When one contemplates those prospects, it’s easy to become depressed.
But we’re not inevitably the losers in our struggles with NCDs. We ourselves are the only ones who created our new lifestyles, so it’s completely in our power to change them. Some help will come from molecular biological research, aimed at linking particular risks to particular genes, and hence at identifying for each of us the particular dangers to which our particular genes predispose us. However, society as a whole doesn’t have to wait for such research, or for a magic pill, or for the invention of low-calorie potato chips. It’s already clear which changes will minimize many (though not all) risks for most of us. Those changes include: not smoking; exercising regularly; limiting our intake of total calories, alcohol, salt and salty foods, sugar and sugared soft drinks, saturated and trans fats, processed foods, butter, cream, and red meat; and increasing our intake of fiber, fruits and vegetables, calcium, and complex carbohydrates. Another simple change is to eat more slowly. Paradoxically, the faster you wolf down your food, the more you end up eating and hence gaining weight, because eating rapidly doesn’t allow enough time for release of hormones that inhibit appetite. Italians are slim not only because of their diet composition but also because they linger talking over their meals. All of those changes could spare billions of people around the world the fates that have already befallen the Pimas and the Nauruans.
This advice is so banally familiar that it’s embarrassing to repeat it. But it’s worth repeating the truth: we already know enough to warrant our being hopeful, not depressed. Repetition merely re-emphasizes that hypertension, the sweet death of diabetes, and other leading 20th-century killers kill us only with our own permission.
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EPILOGUE
At Another Airport
From the jungle to the 405 Advantages of the modern world Advantages of the traditional world What can we learn?
From the jungle to the 405
At the end of an expedition of several months to New Guinea, mostly spent with New Guineans at campsites in the jungle, my emotional transition back to the modern industrial world doesn’t begin at Papua New Guinea’s Port Moresby airport, with which I began this book’s Prologue. That’s because, on the long plane flight from New Guinea back to Los Angeles, I use the time to transcribe my field notes, relive daily events of my months in the jungle, and remain mentally in New Guinea. Instead, the emotional transition begins in the baggage claim area of Los Angeles airport, and it continues with the reunion with my family waiting outside baggage claim, the drive home along the 405 Freeway, and my confrontation with piles of accumulated mail and e-mails on my desk. Shifting from New Guinea’s traditional world to Los Angeles pummels me with a conflicting mixture of feelings. What are some of them?
First and foremost are the joy and relief of being back with my wife and children. The U.S. is my home, my country. I was born and grew up here. Americans include friends whom I’ve known for 60 or 70 years, and who share and understand my life history, my culture, and many of my interests. I’ll always speak English better than any other language. I’ll always understand Americans better than I understand New Guineans. The U.S. has big advantages as a base to live. I can expect to have enough food, to enjoy physical comfort and security, and to live almost twice as long as the average traditional New Guinean. It’s much easier to satisfy my love of Western music, and to pursue my career as an author and university geographer, in the U.S. than in New Guinea. All of those are reasons why I choose to live in the U.S. Much as I love New Guinea and New Guineans, I’ve never considered moving there.
A different emotion hits me when I exit the Los Angeles airport onto the 405 Freeway. The landscape around me on the freeway consists entirely of an asphalt road grid, buildings, and motor vehicles. The sound environment is traffic noise. Sometimes but not always, the Santa Monica Mountains, rising 10 miles north of the airport, are visible as a blur through the smog. The contrast with New Guinea’s pure clear air, the variegated green shades of its dense jungle, and the excitement of its hundreds of bird songs could not be starker. Reflexively, I turn down the volume knobs on my senses and my emotional state, knowing that they will stay turned down for most of the time during the following year until my next New Guinea trip. Of course one can’t generalize about differences between the traditional world and the industrial world just by contrasting New Guinea jungle with the 405 Freeway. The advantage of beauty and of emotional opening-up would be reversed if I were instead returning from months in Port Moresby itself (one of the world’s most dangerous cities) to our summer home in Montana’s gorgeous Bitterroot Valley, under the snow-capped forested peaks of North America’s Continental Divide. Nevertheless, there are compelling reasons why I choose Los Angeles as my base, and why I choose New Guinea jungle and the Bitterroot Valley just for trips. But LA’s advantages come at a heavy price.
Returning to urban life in the U.S. means returning to time pressures, schedules, and stress. Just the thought of it raises my pulse rate and my blood pressure. In New Guinea jungle there is no time pressure, no schedule. If it’s not raining, I walk out of camp each day before dawn to listen to the last night bird songs and the first morning bird songs—but if it’s raining, I sit in camp, waiting for the rain to stop; who knows when that will be. A New Guinean from the nearest village may have promised me yesterday that he’ll visit camp “tomorrow” to teach me bird names in his local language: but he doesn’t have a wristwatch and can’t tell me when he’ll come, and perhaps he’ll come another day instead. In Los Angeles, though, life is heavily scheduled. My pocket diary tells me what I shall be doing at what hour on what day, with many entries months or a year or more off in the future. E-mails and phone calls flood in all day every day, and have to be constantly re-prioritized into piles or numbered lists for responding.
Back in Los Angeles, I gradually shed the health precautions that I adopted as reflexes in New Guinea. I no longer press my lips tightly shut while showering, lest I inadvertently contract dysentery by licking a few drops of infected water off my lips. I no longer have to be so scrupulous about frequently washing my hands, nor about keeping an eye on how the plates and spoons in camp are washed or on who touched them. I no longer have to monitor each scratch on my skin, lest it develop into a tropical ulcer. I stop taking my weekly anti-malaria pills and constantly carrying vials of three types of antibiotics. (No, all those precautions are not paranoid: there are serious consequences to omitting any of them.) I no longer have to wonder whether a twinge in my abdomen might mean appendicitis, at a jungle location from which I couldn’t get to a hospital in time.
Returning to Los Angeles from New Guinea jungle carries for me big changes in my social environment: much less constant, direct, and intense interactions with people. During my waking hours in New Guinea jungle, I’m almost constantly within a few feet of New Guineans and ready to talk with them, whether we are sitting in camp or out on a trail looking for birds. When we talk, we have each other’s full attention; none of us is distracted by texting or checking e-mail on a cell phone. Camp convers
ations tend to switch back and forth between several languages, depending on who is in camp at the moment, and I have to know at least the bird names in each of those languages even if I can’t speak the language. In contrast, in Westernized society, we spend far less time in direct face-to-face conversation with other people. It’s estimated that the average American instead spends eight hours per day in front of a screen (of a computer, TV, or hand-held device). Out of the time that we do spend interacting with other people, most of that interaction is indirect: by e-mail, phone, text-messaging, or (decreasingly) letters. By far most of my interactions in the U.S. are monolingual in English: I count myself lucky if I get to converse in any other language for a few hours a week. Of course, those differences don’t mean that I constantly cherish New Guinea’s direct, intense, omnipresent, full-attention, multilingual social environment: New Guineans can be frustrating as well as delightful, just as can Americans.
The World Until Yesterday: What Can We Learn From Traditional Societies? Page 55