John Durant really likes meat, but he does not keep much of it in his refrigerator—there is not enough room. Instead he stores his meat in a large white freezer chest in his shared Manhattan apartment. Durant, 29, opens the chest and pulls out some frozen chunks of venison wrapped in butcher paper. He digs through the ice to find a couple of cuts of grass-fed beef. He shows me lamb kidneys, pork fatback and ham hocks. As a proponent of what is known as the Paleolithic diet, Durant tries to eat the same way our evolutionary ancestors did. That means big portions of meat, usually red meat—cooked beef, pork, lamb or flesh from other mammals—almost every day.
Durant, who is currently completing a book on the Paleolithic lifestyle, is correct about at least one thing. Without meat, humanity would probably not be where it is today. Evolutionary biologists have shown that hunting game and eating cooked meat significantly altered human anatomy and likely helped us develop bigger brains. Today meat is the largest source of protein in all affluent countries except Japan. Annual global consumption of meat might reach 376 million tons by 2030.
Yet most people in industrial nations live far more sedentary lives than early humans living millions of years ago. Whereas our ancestors worked hard to gather any food at all and most likely confronted the possibility of starvation between successful kills, many of us have easy access to calorie-rich meats whenever we want. Are we in fact eating more meat than is healthy?
Twenty years ago most nutritionists would have said, “Yes,” especially when it comes to fatty cuts, such as hamburger or ribs. After all, the human body readily converts the saturated fat in such meats into cholesterol in the blood, which can in turn lead to atherosclerosis—a leading cause of both heart attack and stroke. In recent years, however, some researchers have questioned whether the link between red meat and cardiovascular disease is as strong as has long been assumed.
A few studies have begun to suggest that some of the ways in which meat is processed—that is, preserved with chemicals—or cooked may be more worrying than its saturated fat content. In addition, researchers now emphasize the importance of looking at the whole diet when trying to figure out what constitutes healthy eating habits. For example, deciding to cut back on red meat while compensating for the loss with comfort foods such as pizza, white bread and ice cream will probably not help anyone. In line with these more nuanced views, many nutritionists have tempered their advice. “A shotgun approach telling people to avoid all red meats may not be the biggest bang for your buck,” says Dariush Mozaffarian, an epidemiologist at Harvard University. “Not all meats are the same. We have choices.” How to make those choices, however, is the subject of ongoing debate.
Man Meets Meat
Before delving into recent, sometimes contradictory, findings about how eating red meat changes our health, it is worthwhile to consider the dietary habits of our evolutionary ancestors. Although the record is by no means complete—and our ancestors' diets varied widely by geography—paleontologists have gathered enough evidence to mark a few milestones. If we travel far enough back in time, to when our predecessors first split off from the last common ancestor we share with chimpanzees, they probably ate fruits, leaves and a smattering of termites. Meat was a very rare treat. As long as three million years ago, however, our ancestors had apparently learned to slice meat off of animal bones with stone tools. At first, these early humans might have primarily scavenged the kills of other predators, stealing bits of meat from a felled gazelle or chasing off smaller carnivores. Learning to cook with fire (at least 400,000 years ago) and the invention of stone spearheads (at least 200,000 years ago) dramatically improved our ancestors' chances of eating their fill.