Big Brains, Small Guts, and the Politics of Meat
If you search the Internet for images of “Paleolithic hunting,” your computer likely won’t show you early Homo chasing hedgehogs. Instead, you will mostly find pictures of mammoths, some elephants, and a few giant rhinos. We seem to have this romantic image of our ancestors taking down only the fiercest and largest of beasts. Does this mean that big game was the best source of nutrition for Homo erectus or, later, for Homo sapiens and the Neanderthals? Not really. Man’s love affair with meat, it appears, was as much about politics and sex as it was about nutrition—if not mostly about politics and sex. Take the story of mammoths, for example.
Mammoth Helmut (so named by his discoverers) is packed into dozens of boxes, stacked high in the French National Institute for Preventive Archaeological Research in Paris. I’m meeting Helmut’s two young discoverers, Grégory Bayle and Stéphane Péan, in front of silicone replicas of the scattered bones, which are so realistic my dogs would probably try to chew them. Just half an hour earlier, Bayle and Péan announced at a small conference that they had found an incision on one of Helmut’s ribs, an incision that might be a cut mark made by Neanderthals scraping off the mammoth’s meat. What’s so unusual about it (if it’s indeed a cut mark) is that we have few such direct proofs of hominins butchering mammoths. That is why many scientists believe that the popular image of our ancestors as expert mammoth hunters is not exactly accurate. There is quite a lot of evidence showing that Pleistocene hunters went mostly for midsized animals, such as bison or reindeer. And yes, sometimes for hedgehogs, too.
Even when humans did hunt mammoths, it might not have always been for their meat. In 2008, far north on the Yana River in Siberia, a massive grave of at least thirty-one mammoths was discovered. The animals were indeed killed by humans—but not necessarily for their flesh. The scientists working on this Siberian site claim that the true booty was the ivory. Just like Greenland Inuits, who used the tusks of narwhals to make spears when wood was scarce, the Siberians of yesteryear used the tusks of mammoths. The meat was just a nice “extra,” not the goal in itself.
Péan, Helmut’s researcher, believes that there were some Paleolithic cultures related to modern humans in Central and Eastern Europe that did hunt mammoths occasionally. In the spring, as the ground thawed and turned soggy with mud, it became difficult for large animals to plod through, so they were easier to kill. But even these mammoth hunters didn’t chase the likes of Helmut solely for their meat. “Hunting mammoths could provide other supplies, such as large bones and tusk ivory to produce varied tools, personal adornment, and art items. It was probably also important for cultural reasons for a group of people to know they can take down such a powerful animal. It might have made them feel stronger and more united,” Péan told me.
In most cases, hunting big game such as mammoths was not necessarily the best way to support a family. It’s true that one dead elephant is equivalent to about five hundred thousand calories, as much as 909 Big Macs. But hunting hippos, buffaloes, or other large game is highly unpredictable and dangerous. Some anthropologists argue that if hunter-gatherers, whether Paleolithic or modern, truly wanted to provide well for their wives and children, they would do better to go for small animals, even insects, and gather seeds and nuts rather than run after elephants.
Killing large game is difficult. The modern Hadza hunters of Tanzania, with their high-powered bows and poisoned arrows (technology that was unavailable to early Homo), fail to bring meat home on 97 out of 100 hunting days. For an hour of work, Hadza men manage to provide on average only 180 calories—that’s less than children harvest from gathering. And yet, Hadza men are not the least efficient providers. Hunters from one New Guinea tribe actually expend more calories hunting than they manage to get from their kills. They’d be better off just sleeping the whole day in the camp.
Another clue that chasing big game is not exactly about nutrition is the timing of the hunts. If hunting big game was about providing food for your hungry family, logic would dictate that you hunt when there is little else to eat and stomachs are empty. Yet that’s often not the case—and probably wasn’t in the Paleolithic, either. Modern hunters go after large animals not in times of scarcity but in times of plenty. The San hunters of Botswana, for example, leave on hunting expeditions exactly when tsin beans and mongongo nuts—great sources of calories, proteins, and fat—are the most abundant. Even chimps are more likely to hunt when there are lots of other foods to eat.
What’s the point, then? Big game hunting is not really about keeping stomachs full. It’s about showing off, politics, and sex. Scoring an elusive prize signals to others that you are strong, skilled, and fearless and that you would make a powerful ally and an adversary to dread. When a hunter did bring home an elephant, it was a great source of nutrition, especially of the highly cherished fat. Five hundred thousand calories is a lot of food. There were no freezers back then, of course, and people didn’t always know how to preserve meat by smoking or salting it. It was better eaten fast. No one can devour an equivalent of almost a thousand Big Macs in a matter of days, but a tribe can, and so the sharing began.
Many social animals share food. Monkeys do it, ravens do it, bats do it, even whales do it. To reinforce bonds, African hunting dogs eat food vomited by other members of the group, and alpha-male chimps use gifts of meat to show favors and establish coalitions. For early Homo meat probably played a similar role. Bringing an elephant to the camp was the Paleolithic equivalent of winning the lottery and writing a big check for charity: it showed that you were a valuable contributor to the public domain, a good neighbor. But hunting big game and sharing the bounty wouldn’t carry much social status if the hunters were unable to communicate. How, otherwise, would people back at the camp know who threw the spear that finished the rhino? How would they know which hunter was brave and which stayed back in fear? Chimps share meat only with those who saw the kill. Humans share it with everyone. To build a reputation and play complicated politics, you need to be able to tell others about the hunt. Some scientists believe that big game hunting could have only emerged among those hominins who could talk. Without language, there would have been no mammoth hunts, no prestige linked to meat, no showing off.
And then, there is sex. From the sky, Juruá River in Brazil looks like a twirling, yellowish ribbon crisscrossing a sea of greenness. On its banks, amid the teeming jungle, live the Kulina, a small tribe of people with sharp cheekbones and wide noses. The Kulina practice an unusual ritual they call “order to get meat.” Whenever the women of the tribe feel “hungry for meat,” they tell the men to go out hunting. At dawn, the women, their straight dark hair hanging loose, stride around the village going from one simple, pillared house to another, rapping at them with sticks and waking the men up. As each man rises from his hammock, the woman who has awakened him makes a promise: if he brings her meat, she will have sex with him that night. And later, after a long day of chasing animals and after a sexually charged ritual feast, she does. In this way, among the Kulina, meat is exchanged for sex.
Other tribes in other parts of the world also value good hunting skills. Studies show that in hunter-gatherer societies, able hunters attract younger and more hardworking wives and tend to have more children than less successful ones. If, as is probable, that was the case in the Paleolithic, too, then such prolific fathers would have been more likely to pass their meat-eating and hunting traditions all the way down to us.
Nevertheless, according to some anthropologists, the role meat played in shaping humanity went far beyond sex and politics. In the words of anthropologist Henry T. Bunn: “Meat made us human.”
Most paleoanthropologists would likely agree that meat eating played a crucial role in turning hominins of the past into the humans of today. It’s likely the reason why we evolved in Africa and not on another continent. East Africa had an important advantage over other places: because of its climate and rich volcanic soils, it offered our ancestors an abundance of medium-sized carcasses to scavenge. In North and South America, the most available meat was packaged into very large animals, which had few predators, died infrequently, and once dead, left carcasses that were difficult to manage—cutting up a mastodon is not an easy task, after all. In Australia, on the other hand, animals were small, meaning that after a carnivore’s feast there would not have been enough meat left to fill hominin stomachs. And without meat, scientists say, we wouldn’t have become as big brained as we are today.
Humans have impressively big brains relative to their body size. African elephants, the largest land mammal, are about fifty times heavier than an average American man, but their brains are only about 3.4 times heavier than human ones. The path to our braininess began about 1.5 to 2 million years ago, when the brains of early Homo expanded by almost 70 percent in just a few hundred thousand years. Most paleoanthropologists agree that such dramatic increases wouldn’t have been possible without a change in diet. Brains are expensive to maintain. Although they account for as little as 2 percent of our body mass, they burn as much as 25 percent of the energy that our bodies need when resting. By comparison, the brains of other primates consume only 8 to 13 percent of the energy needed to run the organism, while those of nonprimate mammals (think mice, polar bears, dogs) use as little as 3 to 5 percent. Our brains are to calories what Hummer trucks are to gasoline—true fuel guzzlers. And yet we don’t need to consume that many more calories to sustain these energy-expensive organs. How is that possible?
One widely accepted explanation is simple: something had to give, and that something was the human gut. To be able to sustain large brains without significantly raising our basal metabolic rate, we had to cut costs somewhere else. We couldn’t reduce the size of other expensive organs, such as the heart, kidneys, or liver, since that would have made the functioning of our bodies impossible. Instead, it appears that sometime in our evolutionary history, our intestines shrank to make more energy available for the growth of our brains. And that wouldn’t have been possible without a better diet.
If you are a Homo erectus and you’d like to meet your calorie requirements on a traditional diet of leaves, fruits, grass, and bark, you would need a large gut to digest it all. Such foods are loaded with fiber and need to be eaten in large quantities to satisfy the requirements of a human body. A fruit-eating Homo erectus, for example, would need to eat eleven pounds of fruit a day—the equivalent of about thirty-three medium apples. That’s a lot of food. Your gut can become smaller only if the things you eat are packed with calories and easy to digest. Peanut butter would have been great, if it were available in the Paleolithic. As it was, our ancestors had to find other high-quality foods to enable the shrinking of their guts and the growth of their brains. That food, most likely, was meat.
It wouldn’t take much. It wasn’t necessary for early Homo to become as carnivorous as saber-toothed cats. If as little as 10 percent of the calories eaten by our ancestors came from meat (about as much as one three-ounce steak on a two-thousand-calorie diet), that would have been sufficient to make a difference between a low-quality and a high-quality diet. Meat was packed not only with calories but also with important nutrients—essential amino acids, iron, calcium, zinc, and sodium, as well as with vitamins A, B1, B6, B12, K, and more.
Was meat the only option? Could our ancestors have improved the quality of their diets without going for animal flesh? Some paleoanthropologists argue that meat alone was not enough to shrink hominin guts: the meat had to be sweetened with honey. Honey is quite the wonder food. It’s one of the most energy-dense substances found in nature; it has antimicrobial, antioxidant, antiviral, and anticancer properties. It helps heal wounds and lowers bad cholesterol. If the honey contains bee larvae—as is often the case in nature—it becomes a good source of protein and fat as well. And last but not least, honey is delicious. It comes hardly as a surprise that hominins have been exploiting this resource for millennia. Today, members of some hunter-gatherer tribes such as the Efé pygmies of Africa eat on average 1.3 pounds of honey per day during the “honey season,” which runs from July through August. That’s 1,900 calories per day in honey.
Another food that has been suggested as “the crucial one” that pushed our ancestors’ diets from low to high quality is tubers—those fleshy plant parts deep in the soil, such as potatoes, yams, and Jerusalem artichokes. But though tubers are nutritious and relatively calorie dense, the wild versions can be buried as deep as ten feet down (and so our ancestors would need quite the tools to dig them up), have extremely hard skins, and are difficult to digest.
But perhaps it’s not about which new food was added to our diet so much as how we prepared it. Richard Wrangham, Harvard University primatologist, believes that it was not just tubers or just meat that made us human but cooked tubers and cooked meat. Wrangham is known in academic circles for his theory that cooking made us human—many scientists I interviewed called him “the cooking guy.” Wrangham argues that cooked food is much easier to digest than raw food, which makes us gain weight faster. Since digestion is an energy-costly process—you burn calories to get calories out of food—the faster you can do it, the more energy will be available for your body. In Wrangham’s experiments, mice fed cooked meat gained more weight than their fellow cage mates who dined on raw food only.
As for the shrinking guts and growing brains of our ancestors, Wrangham believes that raw meat couldn’t have been the instigator. Just look at the dates, he told me. We know that our ancestors were butchering animals 2.5 million years ago, but their brains didn’t start to expand significantly until several hundreds of thousands of years later. That’s a long gap. On the other hand, if around the time their brains began growing, our ancestors also started to cook their food, that, according to Wrangham, would explain their changing physiques.
There is one problem with the cooking hypothesis, though: fire, or rather the lack of it. Wrangham’s critics usually point out that the earliest credible evidence of fire use by our ancestors dates back only to about 790,000 years ago, long after our ancestors’ brains expanded significantly. Wrangham replies that absence of evidence is not evidence of absence and sticks to his theory because, he says, there is no other explanation for how humans simultaneously acquired small guts, small teeth, and weak jaws. But no matter the disputes among scientists of whether it was cooked or raw meat that made us human, most agree on one thing: it was meat.
What about honey and tubers? Most likely, by themselves, those weren’t the foods that enabled the expansion of our brains. But they did smooth the transition to meat. Hunting and scavenging for meat are energy costly (you burn calories when you fight off lions) and risky (the lions may win). So even though meat was a good resource for making our diets high quality, tubers and honey could have helped when there was not enough animal flesh available. They were a nutritional safety net.
Eating meat did more than simply make the expansion of early Homo brains physiologically possible. Eating meat, or rather the organized hunting and power scavenging that it required, and sharing the booty were among the important factors that caused the increase in the relative size of our brains. The Machiavellian intelligence hypothesis states that we needed bigger brains to deal with the complexities of our social lives: the competition and cooperation, cheating and lying, friendship and play. Meat was a big part of that social life. In a way, it allowed us to even have a complex social life. If you eat a low-quality diet of shoots and leaves, the way gorillas do, you need to spend a good part of your day chewing and a good part of it digesting. You’re more or less immobile. Neither gorillas nor orangutans are very social animals: there just aren’t enough hours left in a day. Eating meat, tubers, and honey enabled our ancestors to reassign time from digesting to socializing.
It wasn’t just our brains that grew because of meat; our whole bodies changed as well. Once early Homo became meat eaters, they entered the predators’ guild. It was a dangerous club to belong to. There were many carnivores back then in Africa, many more than today, and the competition was fierce. From simply being an occasional prey, our ancestors suddenly became rivals, hungry for the same gazelles and antelopes. African predators are known to go out of their way to hunt down competition. In the Serengeti, over 70 percent of cheetah cubs die between the teeth of lions but are left uneaten. Adult cheetahs also sometimes fall victim to lions’ competitive streak. It’s very likely that Paleolithic lions, saber-toothed cats, wolf-like dogs, and other big carnivores would want to get rid of early Homo. Becoming bigger is a good way to avoid being eaten: a time-tested strategy pioneered by the earliest eukaryotic cells. Thus evolution favored larger-bodied hominins, and those that lived, for safety, in bigger groups. And bigger groups led to more Machiavellian intelligence and bigger brains.
The thinning out of our body hair over time also likely had quite a lot to do with carnivory—or hunting, to be precise. Hunting is a vigorous activity. Just think of all the running and spear throwing that need to be done. If it’s hot, as was often the case on the African savanna, being covered in thick hair puts you at risk of overheating. That is why, if our ancestors wanted to be good hunters, they needed more adapted bodies. Their hair thinned, and they became better at sweating (for example, we sweat more heavily than our cousins, the chimps—especially on our backs and chests). Once human hair got sparse, the skin got exposed to the fiery African sun. To avoid burns, it became more pigmented, turning darker and darker. And then it came time to move out of Africa: something we might not have been able to do had we not developed a taste for meat.
Finding good food is a big deal when you move to a new country. Whenever I relocate across borders, shopping for groceries becomes difficult, time consuming, even stressful. Something as simple as picking a yogurt off a store shelf becomes a lengthy task of reading labels, comparing prices and ingredients. I have to relearn what I like and relearn which foods taste good, which are healthy and which aren’t. Feeding your family well, it appears, takes a lot of knowledge.
When our ancestors first moved out of East Africa 1.8 million years ago, their quest for good food was much more complicated, and eating meat was a way to simplify matters. Many scientists believe that it was our appetite for meat that helped us move out of Africa and spread around the globe. Imagine what would have happened if we didn’t eat meat back then and only survived on nuts, fruits, and leaves. Africa is a huge continent, with varied climates and ecosystems. In each of these ecosystems, different plants grow. If you are an outsider, it’s hard to guess which ones are edible and which may kill you, making it difficult to move from a savanna you know well to a new environment. But if you are a meat eater, the flesh of one animal is very much like the flesh of another, and in general all mammals and birds are edible. This similarity of potential dinners is one of the reasons why carnivores have larger home ranges than herbivores. Carnivores also need to move around more to find their food. Each day a meat-eating animal will, on average, walk or run four times farther than a plant muncher of a similar size. Meat eating encouraged our ancestors to explore, to step more and more out of their comfort zones. The move out of Africa was not a fast one, though. Our ancestors didn’t just pack their suitcases one day and set off north. As Briana Pobiner told me over an ancient cut-marked elephant bone, “When population density increased, groups just started spacing out a little bit more over time to be able to compete for resources.” After a few thousand years, some of them ended up in Asia and Europe, and moving into these colder areas really forced our ancestors to establish a meat-eating diet.
Life was far from easy for early Homo in Europe. First, there were the plentiful carnivores: wolves, several species of hyenas, cheetahs, pumas, and saber-toothed cats that could weigh up to almost nine hundred pounds. These carnivores were not only happy to eat humans, they also competed with them for food. And in the winter, there was very little else besides meat to fill hominin stomachs. There were no baobab trees, no mongongo nuts, no tropical fruits. Local nuts and seeds, even though highly nutritious, were usually hidden under deep blankets of snow. But there was good news, too. Since European animals carried more fat on their frames to survive the harsh winters, their meat was better for satisfying hunger than that from African animals. If we hadn’t eaten that meat, chances are we wouldn’t have survived in the frosty landscapes of Europe and Asia.
Yet some of our predecessors, the Neanderthals, took it a bit too far. Neanderthals were good hunters. They chased and killed wild boars, gazelles and deer, brown bears, and wild goats. They were highly carnivorous. Analyses of nitrogen isotope values of Neanderthal bones, which can tell scientists where the protein in the diet of a dead organism came from, show that almost all the protein they ate was of animal origin, which would make them almost as carnivorous as wolves or lions. Unfortunately for the Neanderthals, climate change and overhunting drove many species of large herbivores to extinction and decimated others. By the end of the Paleolithic, meat had become harder and harder to come by. Some scientists argue that it was the Neanderthals’ dependence on meat that caused their demise. Anatomically modern humans—or moderns, as paleoanthropologists call them—who lived at the same time in Europe and Asia had a more diverse diet. They were less hooked on meat and supplemented the flesh of terrestrial mammals with birds, fish, shellfish, and plants. A diverse diet is better in times of change: if your favorite food is not easily available, you can switch to the second or third best. But if you only know how to eat meat and have no skills to fish or gather nuts, once the animals you usually hunt are gone, you’re in trouble. What’s more, a diet heavy in meat was quite likely lacking in many nutrients, such as beta-carotene, vitamin E, and vitamin C. This would have meant that the less healthy Neanderthals were likely easily replaced by their better-nourished cousins. And so the omnivorous moderns won, while the Neanderthals went extinct (probably with some direct help from the moderns, too).
For better or worse, meat has played an outsized role in the history of our species. It enabled us to grow bigger brains, encouraged sharing and politics, and helped us move out of Africa and into colder climates. Does that mean we evolved to eat meat? That we are hardwired for animal protein and that we should revert to Paleolithic-style diets that are best suited for our Paleolithic-like bodies? Not exactly. “Paleo” may be in vogue, but there are many problems with the premises on which such diets are based. First, the meat you buy today is not the same as the kind our ancestors got on a Paleolithic savanna. The vast majority of our meat comes from domesticated animals who are bred for a high yield of skeletal-muscle meat and are fed artificial diets in confined spaces. This meat has more saturated fat and so is less healthy. A 3.5-ounce strip loin steak from a wild African red deer would have only 0.6 gram of total fat. A similar-sized beefsteak bought in an American supermarket, even an extralean one, would have about twelve times as much fat. What’s more, modern meat has a much higher percentage of saturated fatty acids (bad for you) and far fewer monounsaturated and polyunsaturated fatty acids (good for you).
Second, there wasn’t one single Paleo diet—either in time or in space. Many of our ancestors were subsisting on leaves, grass, and bark 2.6 million years ago—that’s Paleolithic, too. A million years ago, in Africa, early Homo likely ate some meat, supplemented with high doses of honey, nuts, baobab seeds, and tubers. Sixty thousand years ago, the Neanderthals ate little but mammalian meat, while some of our other ancestors consumed a lot of fish and seafood. Which of these diets is the “right” one? Which Paleolithic period is more “Paleo”? And why do we even say it has to be Paleo? After all, we’ve spent much more of our evolutionary time as insect-crunching primates or, later, as fruit-munching apes. Should we all go insectarian or fruitarian, then? Even today hunter-gatherer diets are extremely varied: some are almost vegetarian, while others are heavy on meat. And yet, Paleo diet gurus seem to suggest that there is just one correct way of eating that best suits our bodies. They often give the exact percentages of protein and carbohydrates that you should eat and tell you to stay away from foods such as potatoes, dairy, and cereal grains. They tell you that you must eat meat. Why? Because (supposedly) our bodies didn’t have enough time to evolve to the new way of eating brought on by agriculture. The problem with this argument is that our bodies did have enough time to evolve—and they did evolve. The evolution didn’t stop ten thousand years ago. According to a growing number of scientists, we have been evolving faster than ever before in the last few thousand years. Studies of the human genome have recently revealed that in the past five to ten thousand years, human evolution has accelerated one hundred times. Several diet-related genes have been identified, genes that evolved after the advent of agriculture. Some of us, it appears, have a new allele (variant of a gene) that regulates blood sugar and protects against diabetes. Others have extra copies of gene AMY1, which helps with the digestion of starches. The most famous example, though, is that of lactose tolerance. Lactose, a sugar found in milk, is indigestible to most adult humans: if you are lactose intolerant and drink milk, you may end up with stomach pains, diarrhea, and even vomiting. Yet lactose intolerance is not common among all nations. For example, in some societies in northern Europe, over 95 percent of the population can digest milk without problems, while only about 1 percent of the Chinese are able to do so. The reason? Early domestication of cattle by northern Europeans and a few thousand years of evolution.
There is one gene, though, that seems to have evolved because of our growing appetite for meat. A rather important gene, too. It’s called apoE, and it comes in three basic variants: E2, E3, and E4. If you have the E4 allele (in many labs you can order a genetic test to determine this), your life may be shortened by several years compared to that of someone who has the E2 or E3 allele. If two people, an E4 carrier and an E3 carrier, both add two egg yolks to their daily diets, the E4’s blood cholesterol may spike up four times more than that of the other guy’s. No wonder that E4 allele carriers have about a 40 percent higher risk of heart disease. So why would nature have us evolve such a lousy variant of a gene? The answer is: to enable us to eat meat. E4 is not all bad news. It developed well before we learned how to control fire and cook our meat. Eating raw flesh is dangerous, especially if it’s scavenged and rotten, crawling with parasites, bacteria, and viruses. Wild chimps, for example, get the deadly Ebola virus from eating colobus monkeys. Yet the E4 gene variant, which boosts the immune response of the body, enabled our ancestors to eat such tainted meals without getting sick too often. Unfortunately, it also put them at risk for aging faster. That’s why a few hundred thousand years later, another meat-adaptive mutation happened, and E3 appeared on the scene. From then on, carriers of this new allele could eat fattier meat without too much risk to their hearts.
Today, some of us are still left with the meat eaters’ version of the gene. Among Americans of European origin, about 13 percent are carriers of this life-shortening allele. The newer E3 is the most common allele worldwide, especially in Japan, China, and India. Does that mean that carriers of these meat-adaptive genes have a particular taste for animal flesh, or that they need meat more than others do? Not at all. Actually, the carriers of the E4 allele would be better off on a low-fat vegetarian diet (although if they wanted to try some rotten meat, they would be more likely to survive this adventure than the carriers of E3 or E2).
We shouldn’t assume that just because a diet is “ancient” it must be good. As one writer joked in an article for the Canberra Times: “Try the latest Paleo diet and you too can be short, stocky, hairy and smelly and . . . then you die.” Cavemen didn’t exactly lead idyllic lives. Their preserved skeletons tell us they suffered from arthritis, gum diseases, deformed limbs, and cancer. Sure, our modern diets are often far from balanced (too much junk food, too much sugar), but they can also be unusually good (veggies from across the globe, fruits year-round, all the seeds and nuts you can imagine). We have options to eat better than our ancestors ever could and ever did. What history can definitely teach us is that we are highly omnivorous and highly adaptable and that we can thrive on many different diets—even rather extreme ones.
Would we have become human had we never developed the taste for meat? Would we have become the big-brained, hairless, social creatures we are today, living across the globe from Europe and Asia to the tiny Pacific islands of Tonga and Nauru? Maybe. Our ancestors didn’t need meat per se to evolve from the hominins of 2.6 million years ago to Homo sapiens of today. Meat was not a physiological necessity. What they did need was a high-quality diet, and at the time meat was the best option they had. That’s why they got hooked on it. Maybe they could have chosen something else. Maybe they could have gone for baobab fruits, which are loaded with proteins and other nutrients. Maybe they could have invested more time in “hunting” insects. After all, chimps can meet their daily protein needs in as little as thirty minutes of termite fishing. Maybe they could have just eaten more honey, tubers, and seeds. All this would have made for a high-quality diet. But, in a way, meat was special. Only meat was both highly nutritious and dangerous to come by (which led to male showing off and politicking). Only meat came in big enough packages to encourage sharing. Only meat required chasing after, which led to us losing our heavy coats of hair. Only meat was basically the same across continents.
What the history of our meat eating can teach us is that our ancestors were highly adaptable. We are not meat eaters by nature so much as we are opportunists. Our ancestors changed their diets quite dramatically several times in the past—from insects to fruits, from fruits to grasses and leaves, from grasses and leaves to meat and tubers—usually in response to changes in climate. Fruits were best for them at some points in the past; meat was best at others. Rather than dumping peanut butter and potatoes down the drain, we should take another lesson from our Paleo (and earlier) ancestors: instead of looking for a perfect and “natural” diet from the past, start looking for one that would be best for right here and right now.
It’s also important to keep in mind that although our ancestors did revolutionize their diets a few times, it doesn’t mean it came to them easily or quickly. After all, they didn’t alter their eating habits over a year or two—it took thousands, at least. Make the change fast, and we may resist. And if the change means less meat, we may resist even more strongly—acting as if without animal flesh on our plates we are doomed to wither and die.
So a new question pops up: Is there some compound in meat that actually helps our bodies function better? Something that, if removed, would mean worse health and less sparkling brains? A vitamin or a macronutrient capable of enticing a powerful hunger-like craving? To answer that question, we must turn from paleoanthropologists and their boxes of bones to biochemists with microscopes and find out meat’s molecular secrets.