Some popular books tell you that because some prehistoric humans lived on large amounts of meat, you should do the same. I think that is lousy advice.
We do know that humans' nutritional needs and system of digesting/processing/using nutrients have not changed significantly in two million years — from our earliest human ancestors.
We are omnivores and can get nutrients from plants, animals or both. The human race has managed to acquire food and survive on every body of land on earth except Antartica, and has adapted to major climate changes. No single food or group of foods is essential; humans can get the nutrients they need from any reasonably varied selection of plants and/or animals as they are found in nature.
We know what our ancestors ate by studying their fossilized feces; as you would expect, they ate whatever was most available in their place and climate – and within their skills. The books that tell you to eat meat focus on groups who had fire and domesticated dogs, hunting weapons, and sparse vegetation – primarily grasses. These people ate mostly meat, as did later people in the far north.
But earlier humans, and those living in more tropical areas, ate huge amounts of plants plus animals that didn't require hunting skills: insects, frogs, snakes, fish, small birds, and scavenged carcasses of animals killed by other predators.
Many of the prehistoric peoples studied appear to have been well-nourished, healthy and not affected by many of our diseases. But their normal life-span was 20-35 years. The diseases and health problems of settled people with agriculture came from many sources: crowding, poor sanitation, higher fertility, reliance on just a few food crops, famines.
The "caveman diet" of the popular authors, based only on meat and those plants that don't need to be cooked, is unreasonably limited and unhealthful for people who expect to live to be 100 or more. Meat from your supermarket is a far from wild game as white bread is from pinenuts. It's 30 percent fat, where game is closer to three percent fat. How can they tell you all our problems come from eating grains and beans, and then say you should eat animals that have been fattened on nothing but grains and beans?
All of the foods in North America today have been transformed through selective breeding from those that were available to our ancestors. They are larger, sweeter, fattier and more prolific. But they still contain the same nutrients as the ancient wild species. Most of our diet problems today stem from man taking things away from the foods that are found in nature – wild or domesticated. (White flour, white rice, milled corn, sugars, extracted oils and fats). When you take away parts of plants and load up just on the parts that taste good, you lose nutrients and end up with too many calories.
Here's my proposal for a hunter-gatherer diet for the 21st century:
Roam around your supermarket and gather anything you can recognize as part of a plant. That means you can pick up just about everything in the produce department. You'll find seeds in the grains section (brown rice, wild rice, barley) and dried beans. Pick some dried fruit, nuts, sunflower seeds. If you find cans or frozen food packages that have pictures of just fruits, vegetables or beans, you can add them too. Go to the spice section and get herbs and spice seeds: poppy seeds, sesame seeds, peppercorns, caraway seeds and the rest. While you're gathering all these plants, if any big game runs down the aisle or flies overhead, you can hunt it down and add it to your cart.