Do Humans Need Meat?

Environmentalists encourage us to cut down on meat consumption in favor of vegetable foods that are less damaging to the environment. Given that our ancestors likely had plenty of meat in their diet, is going meatless a good idea?

The History of Meat-Eating

Our chimpanzee-like ancestors were mostly vegetarian, judging from the diet of modern chimpanzees that subsist mainly on fruit, leaves, and nuts, with a rare morsel of hunted meat. After they left forests in favor of open grasslands, hominids likely increased the proportion of meat in their diet—they would have encountered large herds of game animals.

Initially, meat was consumed raw. About 200,000 years ago, the first hearths appeared, and there is genetic evidence that the human brain began to burn a great deal of energy (1). Cooking partially breaks down food, making it easier to digest. Thanks to the culinary arts, the human gut had less work to do and became much smaller than the digestive system of a herbivorous ape.

At this point, it seems that our ancestors were partly specialized as meat-eaters, although they likely continued to eat a wide range of vegetable foods.

With increased energy use in the brain, we suddenly became a lot smarter. Key evidence for this is that our ancestors refined their toolkit into the efficient technology for killing at a distance that drove many large prey species into extinction around the globe (an event known as the Pleistocene overkill). Everywhere humans migrated, the extinction of many large prey animals soon followed.

Assuming that humans were responsible, our forbears must have eaten a great deal of meat. Ultimately, they may have depleted prey animals so much that they were forced into agriculture to avoid starvation (2).

Even today, meat occupies a special place in the diet, being a preferred food in many societies and therefore taking pride of place at celebrations from the Thanksgiving turkey in this country to the pig feasts that the Enga of New Guinea hosted before making war on their enemies (2).

Meat Hunger and Nutritional Deficiency

We can assume that meat was an important component of the diet right up to the Agricultural Revolution when people began to rely heavily on a small number of cereal crops, such as wheat and rice.

The immediate consequence of this dietary shift was a decline in health and life expectancy. Early agriculturalists were shorter in stature and had lower life expectancy compared with their forager ancestors (2). It seems likely that their health problems were caused more by a decline in nutritional variety than by the loss of meat per se.

There is an ongoing controversy about the adequacy of vegetarian diets. Although vegans—who avoid meat, eggs, and fish—are at risk of nutritional deficiency problems, most experts agree that a wise choice of foods can ameliorate the problems. So, lack of calcium can be addressed by eating collard greens, or tofu, for instance. A scarcity of vitamin B12 can cause anemia and nerve damage but is easily addressed by taking supplements.

In general, modern-day vegetarians are as healthy as their meat-eating counterparts and actually have lower rates of heart disease.

Meat as an Addiction?

Despite limited evidence of the nutritional necessity for meat, people behave very much as though it were a vital component of the diet. A recent book (3) argues that humans are obsessed with meat, noting that in many languages a distinction is made between hunger in general and deprivation of meat.

People who have plenty of vegetables experience “meat hunger.” For that reason, African forest peoples who live largely by hunting have trouble accepting a diet dominated by grains and vegetables (4).

People are hooked on meat due to its taste properties that combine umami (a delicious taste also associated with tomatoes), saltiness, and the distinctive taste of seared fats.

Meat hunger is doubtless controlled by the sensory pleasures of eating animal foods. Why are people so obsessed with meat if vegetable foods provide equivalent nutrients. One long-standing theory, developed by anthropologist Marvin Harris is that people living in a protein-poor environment value meat highly because it is the quickest way for them to secure a balanced diet. Hence the phenomenon of indigenous people, who are well-fed on foods such as bananas, experiencing a powerful sense of meat deprivation.

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Instead of hunting large game, they could theoretically look for alternative protein sources, such as nuts, legumes, or mushrooms. The problem is that such foods are characteristically in short supply for much of the year so that hunted food may be a quick fix for deficiencies of protein and other vital nutrients.

Of course, a solution that worked for our remote ancestors may be out of place in a world where the planet is crowded with people so that meat production is a strain on global resources. In the current environment, it makes more sense to satisfy our cravings with ingeniously contrived substitutes like soy meat.