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Stone Age Aerobics

SPECIAL TO THE TIMES

Instead of heading to the gym at lunch, you might become more physically fit by chasing your lunch, subduing it and dragging it back to your house.

Colorado State University professor of exercise and sports science Loren Cordain has estimated the “exercise regimens” of our prehistoric ancestors--the people who provided the genetic blueprint for modern humans. He concludes that Paleolithic man had a much higher energy expenditure than the modern human.

Consequently, modern humans are genetically predisposed to a more active life than most currently pursue. And that, according to Cordain, is the bad news: Whatever you are doing for exercise, it probably isn’t enough.

To achieve maximum health and fitness, he said, we should take a clue from our more vigorous ancestors. How vigorous? To mimic the hunter-gatherers of the Stone Age, you should strap a 25-pound pack on your back and run 10 miles a day. And, oh yes, change your diet.

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Cordain computed the energy expenditure of Stone Age humans from remains discovered around the world. Then he verified his estimated prehistoric energy expenditure data by comparing it to information collected from existing hunter-gatherer societies such as the Ache in South America, the !Kung in Africa, and the Inuit in the Arctic.

From the shape and size of the bones, scientists can estimate the height, weight and energy expenditure of an individual. Using a formula known as the “Cleaver equation,” Cordain calculated the energy expenditure among prehistoric humans.

Humans in prehistoric times would often spend a day or more tracking and hunting animals at a running or jogging pace--something the African !Kung still do-- and then carry the animal back to camp, again at a pace faster than a walk.

Cordain calculates that primitive men must have run 10 miles a day carrying the equivalent of 25 pounds--a tough day at the office. Women did not get off any easier, carrying children, moving camps, finding and hauling vegetables and other foods and curing meat and hides. That is the kind of exercise regimen built into the human genetic blueprint.

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He does not advocate taking up a hunter-gatherer life during a lunchtime workout. “But,” he said, “by determining the parameters under which we evolved, we can determine the parameters of what we need for optimal health.”

Cordain’s co-researcher, Dr. Boyd Eaton, a radiologist at Emory University School of Medicine in Atlanta and a pioneer in the field of evolutionary medicine, said: “It is not unusual to see an endurance athlete who expends 5,000 calories a day. Construction workers and rural agricultural workers might expend 3,500 calories a day. As best we could determine, hunter-gatherers used 3,000 calories a day. A sedentary American expends about 1,800 calories a day.”

Exercise today is “supplemental,” Cordain said, and in order to achieve our best bodily health, modern people ought to exercise considerably more than they do. He proposes a regimen that includes vigorous workouts, and suggests that daily activities be made more physically demanding--like climbing the stairs instead of taking an elevator at work. But Eaton--who was the director of Olympic Village Polyclinic during last summer’s Olympic Games--said that while any increase in exercise would be marginally beneficial, “some minimal exercise is not going to cut it. In essence, you should be stretching every day, and get aerobic and strength training every other day, for an hour or two hours.”

One implication is the importance of cross-training, including aerobic and weight training, in any fitness regime. “The level of activity needed is more than the minimal level suggested by governing bodies,” Cordain said. Prehistoric man didn’t just jog or lift weights. He took out after his prey at a steady jog, sometimes for many hours and then returned to camp carrying the meat.

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A second result of Cordain’s work is a reconsideration of the human diet. He said it shows that people should eat foods more like those available to their ancestors. The basis of the modern “food pyramid” is cereal grains. “Paleolithic primitive man had only wild, lean game meats and wild vegetables. He didn’t have bread. He didn’t have dairy products,” Cordain said.

So, he maintains, modern humans should concentrate on lean meat and plenty of fruit and vegetables, reducing carbohydrates, dairy products and oily foods to concentrate on fish, chicken and “game meat if possible.”

There is no surviving genetic material with which to compare modern and Paleolithic humans, but most other evidence indicates that there has been relatively little genetic evolution since the Stone Age. There have been some changes since the adoption of agriculture. Caucasians, for instance, have developed an adult lactase gene that allows them to digest dairy products without ill effects. This gene is lacking in most other races, who can’t digest more than about a cup of milk without difficulties.

“This gene has been incorporated in only the last 5,000 years,” Cordain said. “There are other genetic changes in the way red blood cells work that are thought to have occurred only in the last 5,000 or 10,000 years. But we suspect that our genetic makeup is almost identical to our Stone Age ancestors.

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“The closer we can reproduce the environment in which we evolved, the closer we can come to optimizing health and fitness. Hopefully, this means freedom from the common degenerative diseases, heart disease, mental problems and stress. Obviously you can’t go back and be hunter-gatherers. But by emulating what we can of their worlds and leaving out the worst of it , we can get a better shot at optimizing our own health.”

Knowledge about the evolutionary roots of exercise can help guide people through the bewildering and sometimes contradictory exercise advice that inundates the airwaves. “The recommendations are constantly changing,” Eaton said, “Here is a way of looking at something that is not new--it’s old. It doesn’t change.”


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