The "cave man" diet was low-fat and/or vegetarian.
Our Neolithic ancestors were hunter-gatherers, and two schools of thought have developed as to what their diet was like. One group argues for a high-fat and animal-based diet supplemented with seasonal fruits, berries, nuts, root vegetables and wild grasses. The other argues that primitive peoples consumed small amounts of lean meats and large amounts of plant foods. Once again, such notions of a "low-fat diet" are hard to reconcile with what we know of modern-day hunter-gatherer societies. Present-day African tribes readily consume the fatty portions of animals, especially organs such as the brain, liver and tongue. The Aborigines, another hunter-gatherer society, also have a diet rich in saturated animal fats (47).
Explorers such as Stefansson reported that the Innuit and North American Indian tribes would worry when their caches of caribou were too lean: they knew sickness would follow if they did not consume enough fat (48).
Canadian Indians would deliberately hunt older male caribou and elk, for these animals carried a 50-pound slab of back fat on them which the Indians would eat with relish. Native Americans would also refrain from hunting bison in the springtime (when the animals' fat stores were low, due to scarce food supply during the winter), preferring to hunt, kill and consume them in the fall when they were fattened up.
More interesting is the way political prisoners are sometimes tortured in South and Central America: they're fed a diet of lean meat and they die quickly. Why? Without the fat-soluble vitamins contained in animal lipids, the body is unable to utilise and synthesise the proteins and other nutrients present in the meat (49).
On his journeys, Dr Price never once found a totally vegetarian culture. Anthropological data support this: throughout the globe, all societies show a preference for animal foods and fats and people only turn to vegetarianism when they have to (50). Nutritional anthropologist H. Leon Abrams, Jr, has shown that prehistoric man's quest for more animal foods spurred his expansion over the Earth, and that he apparently hunted certain species to extinction (50).
Price also found that those peoples who, out of necessity, consumed more grains and legumes, had higher rates of dental decay than those who consumed more animal products (51). Archaeological evidence supports this finding: skulls of prehistoric peoples who were largely vegetarian have teeth containing caries and abscesses and show evidence of tuberculosis (50, 51).
Based on all of this evidence, it is certain that the diets of our ancestors, the progenitors of humanity, ate a very NON-vegetarian diet that was rich in saturated animal fat.