Criticism of These Proponents’ Speculation

Perlmutter and Taubes’ contrast between prehistory and modernity is simple, stark, and incorrect. This book disagrees that a chasm separated preagricultural and agricultural diets. For example, Chapter 12 notes that southwestern Asians ate wild grains millennia before domesticating them.¹⁶ The same applies to legumes, roots and tubers, and many other foods. The transition to farming continued and intensified preagricultural habits and preferences rather than repudiated them. Moreover, agriculture and animal husbandry did not immediately end hunting and gathering. Chapter 16 states that as late as 1921, for example, American home economist Helen Woodard Atwater (1876-1947) reported game in U.S. rural diets.¹⁷ In other words, Perlmutter and Taubes created a false dichotomy.

The foregoing suggests that their scheme oversimplifies prehistory. Chapter 3 indicated that humanity’s lineage stretches many millions of years into the past. Restricting this time to roughly the last 150,000years, when anatomically modern peoples arose in Africa, still leaves a vast period when humans ate the same proportion of macronutrients according to Perlmutter and Taubes. During roughly the last 50,000years modern peoples colonized every continent but Antarctica, occupying diverse biomes, climates, and topographies; yet these authors want readers to suppose that despite such diversity, humans insisted upon the same high-fat diet everywhere.

Belief that diversity yielded uniformity is untrue. Discussing archaic Homo sapiens’ diets in Chapter 3, Israeli American anthropologist Ofer Bar-Yosef (1937-2020) echoed Donaldson, remarking that people have always eaten what their environment furnished.¹⁸ But environments varied. Chapters 4 and 5 noted that at high latitudes, short summers precluded year-round reliance on plants. Hunter-gatherers adapted by eating game and fish. At the other extreme, Africa and Asia’s tropics, rich in florae, gave prehistoric peoples over 60 percent of calories from plants, estimated Bar-Yosef.¹⁹ Observing today’s hunter-gatherers, Eaton and colleagues asserted that preagricultural diets supplied over 30 percent of calories as protein and below one-quarter as fat.²⁰ Using African herbivores as proxies for game that our ancestors scavenged and hunted, Eaton and American anthropologist Melvin Joel Konner (b. 1946) estimated paleolithic meat under 4 percent fat by mass compared to livestock at “25 to 30 percent fat or even more.”²¹ American nutritionist and exercise physiologist Loren Cordain (b. 1950) put Paleolithic or Old Stone Age (c. 70,000-c. 9000 BCE) fat consumption between 28 and 47 percent of calories.²²

None of these schemes matches Perlmutter’s figures, an unsurprising outcome given that human variability complicates, if not derails, attempts to encapsulate behavior over many millennia in a single set of numbers. Chapter 3 treated humans’ dietary diversity, sketching the variety of plants and animals consumed in pre-Columbian North America alone. Such diversity multiplied on a global scale as people filled innumerable niches. Despite humankind’s flexibility and adaptability, Perlmutter and Taubes redefined us as rigid and unimaginative. In effect, they put humanity on a dietary Procrustean bed. Such an approach rids the past of subtlety.

Besides these flaws, Perlmutter and Taubes unrealistically supposed that hunter-gatherers loaded up on fat from wild animals.²³ They have fat, though the amount varied with their fortunes. During flush times, animals ate their fill and accumulated fat, but scarcity made them lean and hungry. Chapter 3 introduced the phenomenon of rabbit starvation, a type of protein toxicity, whereby people died from eating exceptionally lean animals like rabbits (Oryctolagus cuniculus).²⁴ Such game furnished insufficient fat, carbohydrates, vitamins, minerals, or their combination. Rabbit starvation implies that wild animals were leaner than Perlmutter imagined, especially during privation.

Fat’s quantification in prehistoric game is impossible, a circumstance that invites speculation from Perlmutter and others. Belief that it was very fat seems implausible given that Table 4.1 tabulated 100 grams of bison (Bison bison and B. bonasus) and venison at 7.21 grams and 3.93 grams of fat, respectively. The mean of these numbers is 5.57 grams, or 52.36 calories at 9.4 calories per gram of fat, as Chapter 2 mentioned. Table 4.1 listed 146 calories in 100 grams of bison and 190 calories in the same amount of venison. The mean is 168 calories in 100 grams. These numbers imply that wild animals supplied 31.2 percent of calories as fat. Even if this percentage is doubled to appease Perlmutter, preagricultural peoples would have derived 62.4 percent of calories from fat, not his 75 percent.

New Zealand chemist and food consultant Laurence Eyres regarded game as so lean that he omitted it as a source of fat for hunter-gatherers.²⁵ American historian Kenneth Franklin Kiple (1939— 2016) estimated that such animals by mass had only 10-14 percent the fat in livestock, writing that even where preagricultural diets approached 80 percent of calories from game, only one-fifth of those calories were fat.²⁶ To be fair, Kiple’s numbers—like Perlmutter’s—are speculation, underscoring the difficulty of pinpointing prehistoric fat consumption.

Rather than game, Eyres wrote that preagricultural fat came from fish, nuts, and seeds.²⁷ But if bison, deer (Odocoileus species), and other wild mammals were unlikely to have had ample fat, fish might not have yielded much more. Like mammals, fish are too diverse to permit generalizations. Chapter 5’s Table 5.1 listed 0.96 grams of fat and 86 calories in 100 grams of tuna (Thunnus species), 1.7 grams of fat and 96 calories in the same amount of tilapia (species in the family Cichlidae), 0.41 grams of fat and 56 calories in pollock (Pollachius pollachius and P. virens), 0.67 grams of fat and 82 calories in cod (Gadus morhua and G. macrocephalus), and 11.91 grams of fat and 189 calories in mackerel (species in genera Rastrelliger and Scomber). The means of these numbers are 3.13 grams of fat and 101.8 calories. This quantity of fat has 29.42 calories, yielding 28.9 percent of calories from fat as the average among tuna, tilapia, pollock, cod, and mackerel. Again, doubling this percentage to 57.8 fails to reach Perlmutter’s 75 percent threshold. Citing another example, shellfish fed coastal peoples and have little fat, Chapter 5 and Table 5.2 noted.

Comparisons may be enlarged to include aquatic mammals, birds, and eggs, but these possibilities are no easier to quantify. For example, the U.S. Department of Agriculture (USDA) collects no information about fat and other nutrients in wild eggs. An impression may be formed from eggs laid by pasture-raised hens (Gallus gall us domesticus), which have access to the outdoors. They eat what they find, though owners provide feed and may limit time outside. These conditions do not duplicate existence in the wild, though they may simulate some aspects of it. The nonprofit George Mateljan Foundation tabulated that pasture-raised eggs furnish 64.1 percent of calories as fat, an amount near but still beneath Perlmutter’s boundary.²⁸ These examples suggest that preagricultural peoples ingested under 75 percent of calories from fat.

In evoking prehistory, Perlmutter and Taubes apparently sought evolutionary support for high- fat consumption. The word “evolution” is shorthand for species’ adaptation to their environment over time. Since British naturalist Charles Robert Darwin (1809-1882) published On the Origin of Species in 1859, biologists have described adaptation in reproductive terms. Organisms best adapted to their environment are most likely to survive long enough to populate the world with their offspring. Because progeny tend to resemble parents, organisms with advantageous traits often pass these advantages to the next generation. Over time, organisms with such traits dominate an environment, in this way fitting species to it.

Applying this process (natural selection) to Perlmutter and Taubes’ version of prehistory, hunter- gatherers should have become efficient at digesting and metabolizing fat because they supposedly consumed 75 percent of calories from it and only 5 percent from carbohydrates over many millennia. In other words, a preponderance of fat in diets should have favored the survival and reproduction of people who best digested and metabolized it, ensuring over time that efficient fat burners dominated environments. These fat specialists, seldom consuming carbohydrates, should have been inefficient at digesting and metabolizing them. Because these adaptations to a putatively fat-rich environment enabled our ancestors to populate the world, we must have inherited their advantageous characteristics and so must be most efficient at digesting and metabolizing fat.

Yet physiology rebuts this view because our cells are most efficient at digesting and metabolizing carbohydrates, which the body prefers as energy.²⁹ For example and as Chapter 2 mentioned, the body absorbs between 97 and 99 percent of carbohydrates it ingests, but 95 percent of fat and 92 or 93 percent of protein.³⁰ Like other cells, those in the brain metabolize the sugar glucose (C₆H_l20₆)— Chapter 2 described its manufacture, structure, and metabolism—a carbohydrate. In this context, American nutritionist and dietician Stephanie Green estimated that the brain requires between 50 and 100 grams of carbohydrates daily.³¹ Only inadequacy compels it to metabolize fat. Because the body is less efficient at metabolizing fat or protein, the body prefers to metabolize carbohydrates rather than store them while doing the reverse with fat. Endurance athletes apply this knowledge when they consume carbohydrate-rich foods, a practice known as carbohydrate loading, before competition.³² The outcome of this metabolic bias in favor of carbohydrates is the body’s small supply of glycogen relative to adipose when calories are in excess.³³ Moreover and as Chapter 2 noted, fat metabolism’s inefficiency is evident in that the body requires more oxygen to metabolize a gram of fat than a gram of carbohydrates. From an evolutionary perspective, humans must have adapted to an environment that supplied carbohydrates, not fat or protein, as the primary macronutrient.

American nutritionist Barry Michael Popkin (b. 1944) echoed this judgment, characterizing humanity’s ancestral diet rich in carbohydrates, including fiber, and low fat.³⁴ Saturated fat was especially meager. More active than moderns, paleolithic hunter-gatherers were seldom overweight or obese.

Additionally, Perlmutter and Taubes’ opinion contradicts American botanist Lawrence Kaplan’s (1926-2018) belief that hunter-gatherers first targeted tubers, roots, leaves, insects, and game.³⁵ Chapter 13 indicates that tubers and roots tend to have little fat. Like tubers and roots, leaves are vegetables, most of which Chapter 15 describes as having scant fat. Previous paragraphs debunked the idea that game had much adipose.

Process of elimination leaves insects, which Chapter 3 identified as good sources of several nutrients including fat. Dutch entomologist Arnold van Huis (b. 1946) and coauthors characterized insects’ fat content as “high” while acknowledging their nutrients as “highly variable.”³⁶ Sampling species in Cameroon, Africa, the authors calculated between 9 and 67 percent fat by mass.³⁷ They assigned the highest value (67 percent) to the grasshopper Ruspolia differens, but Kenyan food scientists John N. Kinyuru and colleagues quoted lower amounts of 46.2-48.2 percent.³⁸ These numbers underscore the difficulties of determining fat content today. The problems become insurmountable upon retrogressing millennia into the past. In this regard, conflict between Perlmutter and Taubes’ judgment on one hand and Kaplan’s on the other may be insoluble given inability to pinpoint preagricultural diets’ macro- and micronutrients.

Because the specifics of the preagricultural era faded with time, researchers have used modern hunter-gatherers to approximate the past. Rebutting Perlmutter and Taubes, Eaton and colleague wrote in 1999 that these moderns ate “much less total fat” than developed nations’ denizens.³⁹ Even traditional Inuit diets, treated in Chapter 5, had less fat than today’s U.S. fare. Moreover, Inuit consumed less saturated fat than Americans. These contrasts led Eaton and coauthor to recommend fat intake not above 20 percent of calories and avoidance of saturated and hydrogenated fat.⁴⁰

Grain Brain’s incongruity is that the quest for fatty foods yields the best results for domesticated animals and plants rather than wild ones. Referencing Table 4.1 again, 100 grams of beef and pork supply 5.8 and 15.3 grams of fat, respectively. Readers may recall that the same amount of venison has 3.93 grams of fat. Chapter 8 and Table 8.1 noted that 100 grams of raw peanuts (Arachis hypo- gaea) total 462.86 of 567 calories, or 81.6 percent, as fat. That is, peanuts, the seeds of a domesticated legume, surpass Perlmutter’s 75 percent threshold whereas game, fish, and eggs fall short. Cashews (Anacardium occidentale), a nut from a domesticate, furnish 74.8 percent of calories as fat, an amount within an eyelash of Perlmutter’s boundary.⁴¹ Pistachios (Pistacia vera) exceed it at

75.5 percent of calories as fat.⁴² At 99.5 percent of calories as fat, macadamia nuts (Macadamia integrifolia) also come from a domesticated tree.⁴³ Australian geneticist Catherine Jane Nock and coauthors credited Europeans with domesticating the tree in the nineteenth century.⁴⁴ This list need not be extended to demonstrate that Perlmutter and Taubes are searching the wrong side of the Neolithic divide for abundant fat.

Moreover, an appeal to nuts as fatty foods erroneously supports belief that past diets supplied ample fat because oily nuts seldom sustained populations. Chapter 9 identified as staples acorns (Quercus species) in prehistoric California, Asia, Africa, Europe, and Oceania, and chestnuts (Castanea species) in North America, Europe, Asia, and North Africa. Tables 9.3 and 9.4 listed 100 grams each of dried chestnuts and dried acorns at 4.45 and 31.41 grams of fat, respectively. Calories totaled 374 and 509 per 100 grams of each nut. Repeating earlier calculations, dried chestnuts and dried acorns furnish

11.2 and 58 percent of calories as fat. Once more, these numbers fall below Perlmutter’s 75 percent.

Turning to animals and their products, Chapter 4 remarked that during the Neolithic Revolution, humans domesticated the pig (Sus scrofa domesticus), cow, sheep (Ovis aries), and goat (Capra aegagrus hircus). Pigs supply lard whereas cows, sheep, and goats furnish fat known as tallow. Chapter 7 noted that domestication permitted humans to milk livestock. After animal husbandry arose, people favored milk from cows, sheep, and goats rather than pigs. Chapter 7 indicated that milk and its derivatives contain fat in varying quantities. Whereas fish, nuts, and seeds provided unsaturated fat, dairy foods added saturated fat to the diet, sometimes in sizable amounts. For example, 100 grams of parmesan cheese have 25 grams of fat, 14.9 of them (59.6 percent) saturated.⁴⁵ Saturated fat supplies 35.7 percent of parmesan cheese’s calories. Parmesan cheese’s saturated and unsaturated fats furnish 59.9 percent of total calories.

Besides meat and dairy, the Neolithic supplied cocoa butter—being 65 percent saturated by mass—from cacao (Theobroma cacao) seeds.⁴⁶ Lipids from oil palm (Elaeis guineenis) seeds, known as palm kernel oil, rank higher at 90 percent saturated. Coconut (Cocos nucifera) oil is an even richer source at 92 percent saturated.⁴⁷ By contrast, palm oil comes from fruit rather than seed and is 49.3 percent saturated by mass.⁴⁸ Less may be obtained from cottonseed (Gossypium hirsu- tum and G. herbaceum), peanut, soybean, and olive (Olea europaea) oils, which are 26, 19, 15, and 14 percent saturated, respectively, by mass ⁴⁹

By supplying saturated fat, animal husbandry and agriculture altered the nutrition and diets of people whose preagricultural predecessors had consumed primarily unsaturated lipids. Beginning to collect nutrition and health data in 1952, American physiologist Ancel Benjamin Keys (1904- 2004) correlated early deaths with diets high in saturated fat, which increased cholesterol and blood pressure and heightened the risk of heart disease and stroke.⁵⁰ Smoking and sucrose consumption also exacerbated these dangers. Keys’ work was compelling because of breadth and thoroughness, deriving information over decades from Finland, the United States, Italy, Spain, South Africa, Japan, Bosnia and Herzegovina, Croatia, Montenegro, Macedonia, Serbia, and Slovenia. Table 10.1 encapsulates farming and livestock raising’s effects on dietary proportions of saturated and unsaturated fats by listing eleven lipids.51

The Controversy over Fat Intake

In 1957, the American Heart Association targeted not just saturated fat, advocating a reduction intotal fat intake. Although medical authorities emphasized the link between fat and disease, dieterswho cut the macronutrient did so to diminish calories in hopes of regaining a slim, youthful figure. This approach leveraged the fact, mentioned in Chapter 2, that by mass fat more than doublesthe calories in carbohydrates or protein. A current proponent of lean diets, American nutritionistThomas Colin Campbell (b. 1934)—introduced in Chapter 1—recommended consumption of percent of calories from fat and protein each, and the rest from carbohydrates.52 Parallel to these developments, fat enthusiasts co-opted the message of trimness. American cardiologist Robert Coleman Atkins (1930-2003), introduced in Chapter 4, advocated liberal ingestion of fat and protein, not carbohydrates, as the path toward a slender physique.53 His Dr. Atkins’Diet Revolution: The High Calorie Way to Stay Thin Forever (1972) promoted the illusion thatindulgence yielded leanness, permitting the reader to “eat as much as you want, as often as youwant.”54 Atkins evoked a now-familiar past during which humanity’s ancestors evolved over “fifty million years” to eat fat and protein—stating that the pair’s natural ratio is 40-60—with carbohydratesnear zero.55 These numbers beg citations that Atkins omitted. Chapter 1 mentioned that the keto,

TABLE 10.1

Fat % by Type in Selected Lipids

grapefruit, and paleo diets resemble his formulation. Viewed from this vantage point, Perlmutter is the latest to laud fat and excoriate carbohydrates.

Fatty diets’ proliferation did not eliminate concerns about saturated fat. Since the 1980s, these worries shifted consumption from animal products rich in saturated fat and cholesterol to plant oils with monounsaturated and polyunsaturated fats.⁵⁶ This transition did not reduce fat intake because fast foods and processed items had abundant lipids as well as salt and sucrose. The rest of this chapter examines how fat affected ancient and modern health. The next chapter evaluates carbohydrates as sucrose, honey, and high fructose corn syrup (HFCS).