On a recent visit to New York City, I stopped in to see my prehistoric ancestors. They reside at an enviable address on Central Park West, with floor- to-ceiling windows and a Maxfield Parrish-like mural of the sun fading into an expanse of glowing peaks. With their bulging quads and taut abs, they could (after a good waxjob) resemble a buff couple in the weight room at the local health club.
This prehistoric twosome are my fitness role models. When their contemporaries inhabited the planet about 120,000 years ago, a bench press was just a boulder, Dean Ornish was a gazillion cell divisions in the future, and Central Park West was a hunk of low-rent bedrock. But the Neanderthals were in terrific shape. They hiked many miles a day, burned calories like rocket fuel and gorged themselves unabashedly. They didn't sully mealtime with discussions about cholesterol and trans fatty acids. They were my kind of dinner companions.
I'm not the first to look to the distant past for health and fitness wisdom. Today, as obesity levels in the United States have ballooned to more than 32 percent of the population, putting us at risk for health problems from heart disease to diabetes and cancer, experts are pointing to changes in dietary habits to explain this disturbing trend. "Humans are the only free-living animals who eat food that's unrecognizable in its original form: things like ice cream, bread and macaroni," says S. Boyd Eaton, a physician at Emory University. in his book The Paleolithic Prescription, Eaton refers, in all seriousness, to adhering to a "Stone Age diet" and "foraging" for food in the supermarket. Last year, protein-diet enthusiast Raymond V. Audette even published a tome entitled NeanderThin, which promotes eating beefjerky and shunning potatoes.
In urging us to be true to our origins, Eaton and others hearken back not just to the first Homo sapiens (our own species), who arrived on the scene a mere 50,000 years ago, but way back to their predecessors, Homo erectus, the upright hominids who existed 1.8 million years ago. "Genetically, we've changed only about three one-thousandths of one percent since the Stone Age," Eaton says. But foodwise, we've mutated tremendously.
Our ancestors' lives were shaped by physical activity, but their habitual, vigorous motion had nothing to do with meeting a mate on the StairMaster. Early man and woman worked for their food, toiling over its acquisition, transport and preparation, expending twice as many calories a day as we do. In those days folks got their calories the old-fashioned way: They earned them. It's a simple formula: The more you move, the more calories you burn. Consume more than you burn, and the excess gets stored as fat.
I've been fiddling around with this formula for as long as I can remember. In college, I learned how many calories we burn by just staying alive (about 1,200 for me) and keeping our bodies awake and warm in the cold. Armed with this knowledge, my roommate and I embarked on a creative weight-loss strategy: We stayed up all night and turned off the heat. Our new regimen lasted about two days (we kept ourselves awake by baking cookies), but ever since, I've been aware that my body is a machine and that food is its basic fuel.
For most of us, however, the biological connection between food and work died with the woolly mammoth. Unable to preserve or protect food, our ancestors gobbled down every last morsel to tide them over till the next hunt. We inhale food just to get us through a half-hour sitcom. "Calories are so easy for us to come by," says John Fleagle, Ph.D., a prima- tologist and professor of anatomical sciences at the State University of New York at Stony Brook. Like other primates,Fleagle explains, we're still wired to go for the most calories in the smallest package, like sugar cane or a Snickers bar.
Today the planet's few remaining hunting and foraging societies, such as the !Kung and Hadza of eastern and southern Africa, still exhibit a pattern that Eaton dubs the Paleolithic work rhythm. Amazingly, it could have come straight from the American College of Sports Medicine. These hunter-gatherers walk long distances while stalking wild game.'The women hit the trail to collect fruit, vegetables and seeds, and to haul water, food or firewood, often while carrying an infant or toddler. Activity is strenuous but sporadic, including gathering wood, making tools, butchering meat or postmeal dancing. Among
these tribes, diseases such as obesity and diabetes are rare to nonexistent. One modern pursuit serves as the reference point for my personal Paleolithic prescription: backpacking. A typical day on a mountain trail will cost me an estimated 3,000 calories or more. Those sweaty raimbles put me in Paleolithic mode, during which the notion of cutting calories seems absurd. Eaton concurs that backpacking is as Stone Age as a modern woman can get. We've reduced physical exertion the point where the normal cues aren't operative," he says packing gets us back to were programmed for."
The essence of the hunter-gatherer diet is not only a matter of dietary rhythms but of eating what is freshly picked or killed.  Our Stone Age ancestors consumed about 3,000 calories a day in a diet composed mainly of protein and plant fiber, according to Eaton. As a result, people like Eaton minimize their intake of milk, cheese, rice, pasta and bread. Eaton believes modem foods such as breakfast cereal and ice cream--all dairy as well a refined sugar and processed grains-are alien to our evolution-honed genes, and our bodies have responded to the confusion with a surge in diabetes, heart disease, stroke and obesity.  "No one claims that ice cream is basic for survival," agrees New York
nutritionist Heidi Skolnik, "but it's the amount of these foods we consume and the lack of physical exertion that has led to these diseases." While I'm content marching to the Paleolithic work rhythm and building up calorie credits, I'm less of a purist when it comes to diet. I've never taken a shot at anything live. As for foraging, there is that one week out of the year when I hike into the dunes near my house to gather wild cranberries for my Thanksgiving table. But this pursuit doesn't smack of Paleolithic resourcefulness; it smacks of Martha Stewart.
  Still, I've found that it's possible to incorporate some Stone Age wisdom into my lnformation Age life. I try to get places on my own steam--by bicycle, inline skates or on foot-and I've injected a little spontaneity into my meals by foraging in the market for whatever is freshest. I try to eat raw foods and foods that take a little muscle to prepare, like fresh oranges instead of juice, raw oats instead of processed cereal. Although I'm not NeanderThin, I feel a lot healthier.
   Move habitually, eat guiltlessly: It's a wise, rewarding way to five. It works for me. I may not possess the bod for a swimsuit spread, but I would fare just fine alongside my pals in the Hall of Human Biology and Evolufion.
-Susan V Seligson