Most of us have healthy intentions when it comes to the food we eat. But it can be tough. Especially when you consider that our bodies have not properly adapted to our highly processed fast-food diets.

One hundred years ago, the leading causes of death in the industrial world were infectious diseases such as tuberculosis, influenza, and pneumonia. Since then the emergence of antibiotics, vaccines, and public health controls has reduced the impact of infectious disease. Today, the top killers are non-infectious illnesses related essentially to lifestyle (diet smoking, and lack of exercise). The main causes of death in the United States in 1997 were heart disease, cancer, and stroke. Chronic health problems, such as obesity, non insulin-dependent diabetes, and osteoporosis, which are not necessarily lethal but nonetheless debilitating, are steadily increasing. It is clear that economic and technical progress is no assurance of good health.

Humans are quantitatively different from other animals because we manipulate the flow of energy and resources through the ecosystem to our advantage, and consequently to the detriment of other organisms. That is why we compete so successfully with other species. But with this success come some inherent failings, particularly in terms of our health.

According to physician Boyd Eaton and his anthropologist colleagues, despite all our technological wizardry and intellectual advances, modern humans are seriously malnourished. The human body evolved to eat a very different diet from that which most of us consume today. Before the advent of agriculture, about ten thousand years ago, people were hunter-gatherers, the food varied with the seasons and climate, and all were obtained from local sources. Our ancestors rarely, if ever, ate grains or drank the milk of other animals.

Although ten thousand years seems a long time ago, 99.99 percent of our genetic material was already formed. Thus we are not well adapted to an agriculturally based diet of cereals and dairy products. At least 100,000 generations of people were hunter-gatherers, only 500 generations have depended on agriculture, only ten generations have lived since the onset of the industrial age and only two generations have grown up with highly processed fast foods. Physicians Randolph Nesse and George Williams write: ‘Our bodies were designed over the course of millions of years of lives spent in small groups hunting and gathering on the plains of Africa. Natural selection has not had time to revise our bodies for coping with fatty diets, automobiles, drugs, artificial lights, and central heating. From this mismatch between our design and our environment arises much, perhaps most, preventable modern disease.’

Do we really want to eat like prehistoric humans’? Surely cavemen were not healthy? Surely their life was hard and short? Apparently not. Archaeological evidence indicates that these hunter- gatherer ancestors were robust, strong, and lean with no sign of osteoporosis or arthritis —- even at more advanced ages. Paleolithic humans ate a diet similar to that of wild chimpanzees and gorillas today: raw fruit, nuts, seeds, vegetation, fresh untreated water, insects, and wild-game meat low in saturated fats. Much of their food was hard and bitter. Most important, like chimpanzees and gorillas, prehistoric humans ate a wide variety of plants — an estimated 100 to 300 different types in one year. Nowadays, even health-conscious, rich westerners seldom consume more than twenty to thirty different species of plants.

The early human diet is estimated to have included more than 100 grams of fiber a day. Today, the recommended level of 30 grams is rarely achieved by most of us. Humans and lowland gorillas share similar digestive tracts — in particular, the colon — but, while gorillas derive up to 60 percent of their total energy from fiber fermentation in the colon, modern humans get only about 4 percent. When gorillas are brought into captivity and fed on lower-fiber diets containing meat and eggs, they suffer from many common human disorders: cardiovascular disease, ulcerative colitis, and high cholesterol. Their natural diet, rich in antioxidants and fiber apparently prevents these diseases in the wild, suggesting that such a diet may have serious implications for our own health.

Not all agricultural societies have taken the same road. Many traditional agriculturalists maintain the diversity of their diet by eating a variety of herbs and other plant compounds, along with meat and grain. The Hausa people of northern Nigeria, for example, traditionally include up to twenty wild medicinal plants in their grain-based soups, and peoples who have become heavily reliant on animal products have found ways of countering the negative effects of such a diet. While the Masai of Africa eat meat and drink blood, milk, and animal fat as their only sources of protein, they suffer less heart trouble than Westerners. One reason is that they always combine theiranimal products with strong, bitter antioxidant herbs. In other words, the Masai have balanced the intake of oxidizing and anti-oxidizing compounds. According to Timothy Johns, it is not the high intake of animal fat or the low intake of antioxidants that creates so many health problems in industrial countries; it is the lack of balance between the two.

Eating the right foods and natural medicines requires sensitivity to subtle changes in appetite. Do | fancy something sweet, sour, salty, stimulating, or sedating? What sort of hunger is it? And after consumption, has the need been satisfied? Such subtleties are easily overridden by artificially created super-stimuli in processed foods that leave us unable to select a healthy diet. We need to listen more carefully to our bodies’ cravings and take an intentional role in maintaining our health before disease sets in.