Q: You've mentioned that certain foods are healthy because our bodies evolved to benefit from these plants and animals. What do you think of the Paleolithic diet? — Maria Velasquez, San Diego
A: I am a strong proponent of mimicking much of our early ancestors' way of eating, but that doesn't always go hand in hand with the so-called Paleolithic diet that has been popularized in recent years. The theory behind this approach is that by eating the food we, as a species, evolved to digest, we can help reduce our risk of heart disease, cancer, and obesity.
But there's actually some disagreement over what that diet really looked like. The term Paleolithic refers to the early Stone Age, an era of hunting and gathering. Some experts have emphasized the hunting part, recommending that we eat plenty of meat. However, many anthropologists prefer describing our ancestors as gatherer-hunters because about two-thirds of their diet was plant based.
Another discrepancy between today's version of the diet and the original is that the meat we eat today just isn't the same as it was a million or so years ago. The flesh of antelope, which paleontologists believe most resembles the flesh our Stone Age ancestors would have eaten, has a very low fat content, roughly 16 percent of total calories. Contrast that with beef, which can be 30 percent fat or higher. Even more important is the quality of the fat. Meat from animals that graze on grass contains a much higher proportion of polyunsaturated fat, including those heart-healthy omega-3s. These are mostly missing from corn-fed domesticated livestock, whose meat delivers much more saturated fat.
So I'm sorry to say that the modern Paleolithic diet isn't an excuse to load up on hamburgers and hot dogs. The most accurate interpretation in my opinion is that you should get 60 to 70 percent of your calories from plant foods, nuts, and seeds, and the rest from game—not domestic meat.
There are, in addition, limits to how knowledge of evolutionary biology can be applied to nutritional health. Our Stone Age ancestors lived to only about the age of 40—who knows how their health would have fared after 80 years of eating like this? The dietary plan I prefer to espouse is one supported by both anthropology and modern science: plenty of vegetables, fruits, and whole grains as a stand-in for the wild plants our ancestors ate, nuts and seeds, beans, seafood, lean meats, eggs, and low-fat or nonfat dairy. That's a plan inspired by the Stone Age but not stuck in it.