How We Grew So Big — page 4

That was the condition of pretty much the entire human race when anatomically modern humans first arose, between 150,000 and 100,000 years ago, and things stayed that way until what some anthropologists have called humanity's worst mistake: the invention of agriculture. The ancient Chinese were among the first people to develop farming, growing rice along the banks of the Yangtze River. Nutritionally, the shift away from wild meat, fruits and vegetables to a diet mostly of cultivated grain robbed humans of many of the essential amino acids, vitamins and minerals they had thrived on. Average life span increased and population density exploded, thanks to the greater abundance of food, but average height diminished. Skeletons also began to show a jump in calcium deficiency, anemia, bad teeth and bacterial infections. Most meat that people ate came from domesticated animals, which have more fat than wild game. Livestock also supplied early pastoralists with milk products, which are full of artery-clogging butterfat. But obesity wasn't a problem, because even with animals to help, physical exertion was built into just about everyone's life—as can still be seen in the most rural areas in Asia.

That remained the case practically up to the present. It's really only in the past 100 years that cars and other machinery have dramatically reduced the need for physical labor—in many parts of Asia, those technological changes are even more recent. And while exercise has vanished from everyday life, the technology of food production has become much more sophisticated. In 1700, Britain consumed almost 21,000 tons of sugar. That was about 3.4 kg of sugar per capita. The global consumption of sugar is now some 46 kg per capita. Farmers armed with powerful fertilizers and high-tech equipment are growing enormous quantities of corn, wheat and rice, most of which is processed and refined to be tastier and more convenient but is less nutritious. They are raising vast herds of cattle whose meat is laden with the fat that makes it taste so good. They are producing milk, butter and cheese by the tankerload, again full of the fat that humans crave. And thanks to mass production, all that food is relatively cheap.

For Asians, the rapid shift from undernutrition to caloric overdrive is especially fraught with risk. Some scientists believe that many Asian populations, particularly South Asians, evolved a so-called "starving gene" after living for thousands of years under near-famine conditions. That may have left them with bodies that are paradoxically too metabolically efficient to deal with the relative abundance of modern life. "It's a genetic trait that benefited them in the past when food was often scarce, but when food is plentiful all the time, it becomes detrimental," says Professor Brian Tomlinson of the Chinese University of Hong Kong.

There's no doubt that the obesity epidemic is real and our collective metabolic health has been getting progressively worse. Indeed, says Yale public-health expert Dr. David Katz, "today's kids may be the first generation in history whose life expectancy is projected to be less than that of their parents." But there's plenty of reason for hope. Researchers are hard at work trying to understand the basic biochemistry of hunger and fat metabolism; countries such as Singapore are finding success in actively fighting the rise of obesity; and Asians in general are beginning to wake up to the importance of healthy diets and regular exercise. The WHO World Health Assembly recently passed a landmark global strategy on diet and physical activity that aims to help member countries combat the growing and expensive burden of obesity-related noncommunicable diseases.

In the past, campaigns against infectious diseases and other enemies of public health have dramatically improved the quality of life throughout Asia. Now, a region that had trouble feeding itself just 50 years ago must battle the unintended effects of its amazing economic success. To win this war will require nothing less than conquering millions of years of evolution.

With reporting by David Bjerklie/New York City

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