Abstract
Our human ancestors thrived on a diet high in fat and protein of animal or fish origin for at least 2.5 million years. Foods with a high-energy content and nutritional density were required for the development of the large, energy-expensive human brain. A reduction in human height and deterioration in our health followed the introduction of agriculture 2 000-12 000 years ago. In 1977, the United States Department of Agriculture (USDA) introduced novel dietary guidelines based on an untested hypothesis of Keys that dietary fat, especially of animal origin, increases the blood cholesterol concentration, “clogging” the coronary arteries and causing heart attacks, i.e. the diet-heart hypothesis.