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What Should We Eat and How Should We Live?
Around the world, people are increasingly beset with vexing conditions like obesity, type 2 diabetes, gout, hypertension, breast cancer, food allergies, acne, and myopia. Dubbed the “diseases of Western civilization,” these conditions have become more common in recent centuries and decades, with emigrants to more affluent regions of the world often at higher risk for developing afflictions as they adopt the customs and diet of their new home. It’s true that better medical care and longer life spans are exposing people to new kinds of diseases. Still, the rapid advance in these conditions signals that something else is going wrong—but what?
The principal argument of 100 Million Years of Food is that a plethora of health woes have surfaced in contemporary times due to our alterations to our ancestors’ diets, lifestyles, and environments. I will explain how our ancestors used to eat and live and will offer practical suggestions for tweaking ancestral habits and inserting them into our daily lives to avoid or delay the onset of major chronic diseases.
Eating and living like our ancestors seems common sense, and many books have attempted to relate how this can be done. Unfortunately, there is great disagreement about what aspects of ancestral eating and living should be adopted. For example, in some versions of ancestral diets, readers are advised to avoid agricultural staples like bread, rice, beans, and milk in favor of meat and vegetables, while others argue that traditional American farm diets that included bread, beans, and milk are best for health.
My parents immigrated from Vietnam to Canada in the 1960s. They met at a college in Montreal and brought up three boys in the maple-lined suburbs of Ottawa. Due to my obsession with insects and other critters, I was designated the family science nerd. I received a microscope as my Christmas present in fourth grade, which I used to peruse squished mosquitoes on glass slides. The following year, a paperback edition of Charles Darwin’s On the Origin of Species arrived under the Christmas tree. The letters in the book were extremely small, and the language was unintelligible to an elementary school kid, but I sensed there was something revolutionary between the pages.
When I was eight years old, my grandmother arrived from Vietnam. When I first met her she was wrapped in a shawl, hunched and wizened, a mage. Grandma opened her luggage and handed me a belt wrought from links of varnished wood, along with an exquisite slice of dried banana, the honeylike taste of which lingers with me to this day. During a school holiday when my younger brother and I visited the apartment that Grandma shared with my aunt, I found no high-energy snacks of nuts and dried fruits, no fruit bars, no yogurt, no blaring TV, just a rocking chair, a few shelves of incomprehensible books, a bottle of fish sauce, a rice cooker, some crumpled old linen towels, and the soft light of day streaming through the window. Oblivious to official pronouncements on nutrition—she spoke no English—Grandma went on living the way she had always lived, eating the way her ancestors had: a bowl of rice, clumps of dried shredded pork, a sprinkling of fish sauce, and a pile of stir-fried spinach. I was glad to head back home that evening to my video games and high-energy snacks.
The significance of my grandmother’s diet didn’t hit me until I visited Vietnam for the first time when I was twenty-five. Wherever I traveled in the country, I drew attention because I towered over the local Vietnamese. Despite being under average height and weight among my peers in Canada at 5'8" and 150 pounds, I was still four inches taller and twenty-seven pounds heavier than my peers in northern Vietnam, who were in turn one inch taller and eighteen pounds heavier than their peers a generation earlier.1 Why the rapid change? When I was invited to meals around Vietnam, hosts often prepared a feast with pork, chicken, or fish in bountiful proportions. However, when I showed up unexpectedly at mealtimes with ordinary folks, I glimpsed the real side of everyday rural cuisine: rice, paddy or jungle vegetables, fermented fish or soybean sauce for flavoring, tofu, and bits of crab and fish. North American diets rich in meat and milk had evidently made me taller, but as I later learned, such fare also put people who consumed it at greater risk of certain chronic diseases.
Back in Canada, my mother developed breast cancer, which metastasized to her lungs. After I finished my doctoral studies in Los Angeles, I spent three months at home, helping to tend to my mother’s needs. She passed away at the age of sixty-six, only two years after her own mother passed away at ninety-two. In the aftermath, everyone in our family had a different means of coping. Dad channeled his energies into community activities; my brothers had their wives and children to occupy them. I decided to focus on researching ancestral diets and lifestyles and learning about the risk factors behind breast cancer and other diseases commonly associated with Western civilization.
I studied biological anthropology (the study of human evolution) at the University of California, Los Angeles (UCLA), then spent two years researching food and food-related illnesses around the world, observing and sampling what people ate and chatting with food producers, health experts, and other people connected to eating and nutrition. I began to understand why health experts disagree sharply on which foods are healthy. First, there is a lot of confusion over the difference between short-term and long-term health. A diet that makes a person taller, a weight lifter stronger, and a woman more fertile is healthy to a degree, but generally not a diet that would make a person live longer. This makes perfect sense from an evolutionary point of view, as will be discussed in this book, but the distinction between short-term and long-term health is often overlooked or misinterpreted by many health researchers. This brings us to the second major mental stumbling block encountered by nutritionists and food writers: the tendency to ignore or misunderstand human evolution and to focus instead on simplistic models of human nutrition and physiology. Trying to understand human nutrition and health without understanding evolution is like trying to eavesdrop on a snippet of conversation without knowing the context—it makes little sense or can be very misleading.
As a result of my observations and reinterpretation of scientific studies related to food, I discovered a series of measures that people can take to improve their health. These interventions are discussed throughout the book and summarized in the afterword. However, there are three steps that I consider the most important to improve the health of someone living in modern societies today. They are:
Keep moving. The vast majority of food-related illnesses stem from a profound shift in human lifestyle, from constant, challenging physical and mental activity to sedentary life, punctuated only (if at all) by spurts of frantic exercise. Paradoxically, although a common belief is that our ancestors burned a lot more calories doing physical activity than people today, the evidence does not support this assumption. Moreover, although physical exercise has exploded in popularity in recent decades, obesity rates in North America also rose during that period. Critics of the link between physical exercise and obesity have pointed out that exercise just makes people hungrier, leading them to eat more, and the body compensates by lowering metabolism, obliterating any gains from working out.
As it turns out, the clincher may lie in patterns—rather than amount—of physical activity. (Decreased mental activity may also be a health risk, as discussed later.) Our male ancestors covered around nine miles per day on foot, while women walked around six miles each day. Walking decreases IGF-1 (insulin-like growth factor-1) hormone levels, which implies lower risk of hormone-related conditions like breast and prostate cancer and acne. Prolonged walking also reduces the risk of diabetes and is associated with weight loss. By comparison, the average American covers about two and a half miles on foot each day and spends the rest of the time sitting, driving, and watching nearly five hours of television. Watching TV is associated with an increased risk of obesity, type 2 diabetes, cardiovascular disease, and simply outright dying.
Eat less meat and dairy when younger. Avoid sugar and deep-fried foods. Meat was an important part of the human diet starting from at least two million years ago, but for most of the last twelve thousand years, almost all humans have had much less access to it. Cows and goats were milked by some populations beginning around nine thousand years ago, but for most of these populations, dairy was a much-appreciated substitute for meat and animal fat. Meat and milk are extremely nutritious, providing all the required amino acids, minerals, fatty acids, and vitamins to sustain human life, but the combination of these two nutritionally rich items in recent times was unprecedented in human history—and too much. Furthermore, as nations became richer, people were also able to purchase sugar and vegetable oils.
Hormonal activity, such as that of insulin and IGF-1, goes haywire when we consume a lot of animal protein and sugary and fried foods.2 Eating more animal foods will probably make you taller, stronger, more fertile, and feel better, but these foods will also likely shorten your life span. Meat is most hazardous for the long-term health of younger people, because cancers and other chronic conditions generally take decades to develop and manifest. On the other hand, older people’s health may benefit from the rich nutritional properties of animal foods. The irony is that we spoil our children by letting them eat liberally and then counsel ourselves to restraint when we are in our advanced years and suffering from chronic diseases. This is exactly the wrong strategy. If helping kids avoid chronic diseases is the goal, parents should limit their children’s intake of animal foods; on the other hand, we can encourage elders to eat meat and be merry.
Eat traditionally. Rather than worry about what to eat and what to avoid, a good fallback is to eat traditionally. Traditional diets took centuries to develop and are based on how well combinations of food supported health and on how good ingredients tasted together. Faced with depleting meat stocks, our ancestors devised innumerable methods of cooking delicious and healthy meals that balanced nutrients. Furthermore, in societies where people lived on particular diets for hundreds or thousands of years, their bodies gradually became adapted to the diets, such as the case of lactose (milk sugar) digestion for people in northern Europe and India, and in East Africa. Eat traditionally and eat what your ancestors ate.
One problem with this strategy is that many people don’t know what their ancestors ate. In 100 Million Years of Food, we’ll venture through the major stages of food history, from fruits, meat, starches, alcohol, and dairy to aquaculture and genetically modified crops, explaining why we ate various foods and the impact these foods have on our health. First, though, we’ll step back a hundred million years in time and consider a food that some of our most distant ancestors evidently relished: insects and their creepy-crawly kin. Good enough for our ancestors—and good enough for us?
Copyright © 2016 by Stephen Le