Of berries and bison: stone age standards for modern diets.

Reverting to old habits might not be such a bad idea, at least when they're the dietary habits of prehistoric ancestors. The ancient diets are "genetically what we are designed to eat, digest and metabolize," says S. Boyd Eaton, a physician at Emory University in Atlanta. He and anthropologist Melvin Konner suggest in the Jan. 31 NEW ENGLAND JOURNAL OF MEDICINE that veering from this nutritional genetic program might be why modern humans suffer from "diseases of civilization," while modern hunter-gatherers, who most closely resemble our Stone Age ancestors, do not. Other researchers, however, caution against assuming modern humans should follow ancient diets.

Physicians and nutritionists have become increasingly convinced that modern

diets play a role in the development of cancer, hypertension, diabetes and heart disease. These "diseases of civilization" are among the top killers in Western society, but they are virtually unknown among the few surviving hunter-gatherer populations. For example, when diabetic Australian aborigines living near Melbourne returned to their hunter-gatherer lifestyle, their diabetic abnormalities improved greatly, according to an earlier study reported in the June 1984 DIABETES.

Eaton and Konner used nutrient values for foods eaten by modern hunter-gatherers to estimate the daily nutirent intake of Paleolithic humans, who lived from the first manufacturer of stone tools about 1.6 million years ago to shortlsy before the advent of agriculture 10,000 years ago. The researchers say the diets of these humans might provide standards for modern nutrition.

But the standards would have to be adapted to modern lifestyles. For instance, Paleolithic humans ate much more meat than nutritionists recommend today. Yet changing modern diets to include more meat could be disastrous because the wild game consumed by hunter-gatherers is much less fatty than the highly marbled cuts available in supermarkets today. Eaton suggests substituting fish and pultry for high-fat meats.

Paleolithic humans broke a fundamental rule of modern nutrition by consuming foods from only two food groups -- meats and fruits/vegetables -- rather than the traditional four. They ate cereal grains only rarely and dairy foods not at all. Yet because they ate lots of meat and a wide variety of vegetables, they consumed twice as much calcium and fiber and four times as much vitamin C as modern humans.

Stone Age diets also violated current cholesterol recommendations. The report says the diets "must have greatly exceeded the U.S. Senate Select Committee's recommended cholesterol level." But their serum cholesterol levels were low, Eaton says, because they ate more polyunsaturated and less saturated fat.

Ancient humans ate only one-sixth the sodium in a typical American diet--only one-third the soldium recommended by nutritionists today. The dietary potassium-to-sodium ratio would have been about 16 to 1, the Emory researchers say, compared with today's recommended 1.7 to 1. A recent study suggested that high potassium intake might be worth copying as a protection against high blood pressure (SN: 1/26/85, p. 57).

some researchers question the Emory study's findings. Anthropologist Alan Walker of Johns Hopkins University in Baltimore challenges the assumption that humans haven't had time to make genetic adaptations to dietary changes.

But both Walker and the Emory researchers say that human genes probably won't change to adapt to dietary changes implicated in diseases of civilization. "The diseases that kill us now kill us after child rearing," Eaton says, "so there's not much selective pressure to influence evolutionary change."