Fruits

Definition and Seed Dispersal

Chapter 9 mentioned that a fruit is a flower’s fertilized ovary, which develops to hold seeds. This definition encompasses edibles that popular opinion denies as fruits, including corn (Zea mays) kernels, cucumbers (Cucumis sativus), peppers (Capsicum species), eggplants (Solatium melon- gena), squashes (Cucurbita species), almonds (Amygdalus communis), pecans (Carya illinoinen- sis), okra (Abelmoschus esculentus), legumes (species in the family Fabaceae or Leguminosae) and other pods—though pod’s removal eliminates the seeds as fruits—tomatoes (Solanum esculentum) and olives (Olea europaea).¹ The public discounts these items in the conviction that only sweet, juicy, or pulpy produce not eaten as an entree qualifies. Desserts such as apples (Malus domestica), bananas (Musa x paradisiaca), or sweet oranges (Citrus sinensis) come to mind as archetypal fruits in the United States, though there is no worldwide standard of what is appropriate for dessert or whether a meal must include it.

A fruit’s color, aroma, flavor, or their combination attracts animals to eat it. This occurrence may seem strange because animals flee predators rather than submit to consumption. In this instance, however, comparison between plants and animals is unhelpful because plants’ rootedness precludes the mobility evident in animals. More fruitful is recognition that plants, like all life, seek to pass their genes to the next generation.

Every spring my sour cherry trees (Prunus cerasus) pollinate, producing fruit that ripens in June. If all cherries fell from the trees, the germinating seedlings would occupy a tiny area. In competition for sunlight, water, and nutrients, each would crowd out its neighbors so that none would survive to maturity and so would fail to perpetuate themselves. But they avoid this fate. Whatever cherries I do not pick lure birds to devour them. They fly away, swallowing each fruit and defecating the pit distant from the trees. Dung fertilizes the soil, aiding germination and growth of seedlings that, no longer facing crowding and competition, grow' to maturity if nothing kills them beforehand. In other words, fruit aids seed dispersal, giving seedlings the best prospect for success in a hostile world.

Fruits and Primate Evolution

Among animals drawn to fruits were humanity’s forebearers.² American nutritionist and exercise physiologist Loren Cordain (b. 1950) stated that fruits were part of “humanity’s original way of life.”³ British ecologist Stanley Jan Ulijaszek (b. 1954), Australian nutritional chemist Neil Mann, and British anatomist Sarah Elton traced frugivory (fruit eating) to the first primates.⁴ Readers may recall that Chapter 3 dated primate origins no earlier than about 65 million years ago. Fruits were not the lone food, but they were important as sources of fiber, minerals, vitamins, protein, and energy in the form of sugars, especially the monosaccharides glucose and fructose.⁵ Chapter 2 noted that both have the formula C₆H₁₂0₆ and that glucose is photosynthesis’ primary product. Domestic fruits tend to have more sucrose (C₁₂H₂₂O_n), a disaccharide, than their wild counterparts. Other fruit sugars include sorbitol (C₆H₁₄0₆).⁶ Sugars made fruits tasty and easy to digest. Through experimentation, primates learned to equate sweetness with edibility and bitterness with toxicity.

Fruit sugars introduced early primates to the alcohol ethanol (C₂H₅OFI) through fermentation. Humanity’s enthusiasm for ethanol as beer, wine, spirits, and kindred products may derive from primates’ exposure to it by eating fruit that had begun to ferment. Dates (Phoenix dactylifera) may have been the first fruit that prehistoric peoples converted into w'ine.⁷ Wine from grapes (Vitis vinifera) emerged as a beverage throughout the Mediterranean, separating this region from northern

Europe, which relied on beer and—Chapter 11 noted—developed a preference for sucrose in the Middle Ages.⁸ Wine or another alcohol diluted with water was a safe beverage because ethanol killed pathogens that contaminated water.

Among nutrients, fruits tend to have vitamin C (ascorbic acid), which Chapter 2 mentioned as water soluble. This characteristic requires the body to consume vitamin C regularly to offset excretion in urine. Humankind’s lineage lost the ability to manufacture this vitamin around 60 million years ago, implying that our ancestors had such ample access to fruits, vegetables, and other vitamin C sources that natural selection no longer favored individuals that made the nutrient.⁹

The issue is whether this plentitude was periodic or continuous. The need for regular ascorbic acid intake indicates that humanity’s ancestors ingested it often, but this requirement does not prove frequent fruit consumption if other foods could be substituted for the vitamin. American cardiac surgeon Steven R. Gundry averred that fruit was available only seasonally until globalism permitted purchase even when unavailable locally.¹⁰ American neurologist David Perlmutter (b. 1954)—introduced in Chapter 1—agreed, writing that as late as 1900, fruit was eaten only in season.¹¹

Seasonality required consumption of vitamin C substitutes when fruit was unobtainable. American anthropologist Stephen Le specified insects in lieu of fruit for vitamin C.¹² This claim is inaccurate because insects tend to be poor sources of it, though many species have В vitamins, E, fiber, minerals, protein, fat, and carbohydrates.¹³ Their elimination as vitamin C candidates and fruit unavailability year-round narrows the possibilities to leaves given Ulijanszek, Mann, and Elton’s description of primates as frugivores, insectivores, folivores (leaf eaters), or their combination.¹⁴ Because our primate forebearers lived near the equator, only tropical leaves qualify as potential vitamin C sources. A 2010 paper identified leaves of six wild tropical plants as rich in this vitamin.¹⁵ This number does not exhaust the possibilities but suffices to demonstrate that our ancestors could have ingested vitamin C year-round without eating fruit.

The foregoing does not diminish fruits’ importance to our predecessors. Avid fruit consumption between roughly 60 and 30 million years ago caused them to evolve flat molars suitable for soft or hard fruits rather than ridged molars ideal for grinding insect exoskeletons.¹⁶ To be sure, our ancestors ate insects, which supplied complete proteins absent in fruits. Leaves too remained in prehuman diets. Like us, our precursors were omnivores and eclectic feeders who targeted many foods. Chapter 3 detailed primate diets’ evolution.

Moreover, fruit consumption may have hastened primate brain growth. Chapter 4 discussed anthropologists’ belief that meat fueled encephalization during roughly the past 2 million years. This expansion augmented the brain that frugivory had enlarged millions of years earlier. Notable in this regard, frugivorous primates have larger brains than folivores.¹⁷ Ulijaszek, Mann, and Elton believed that enlargement resulted from frugivores’ need to map mentally their surroundings to know where and when fruits of various trees ripened.

Cognitive cartography took primates to distant locations when fruit was sparse, developing the nomadism that defined hunter-gatherers.¹⁸ Coverage of long distances in search of fruits may have hastened evolution of bipedalism, an efficient locomotion. Humanity’s colonization of every continent— though no one permanently inhabits Antarctica—contrasts with most primates’ confinement to the tropics and may have stemmed from the quest for ripe fruit. Chapter 3 described humans’ worldwide dispersion.

Fruits’ Critics

Fruits’ importance to our evolution has not prevented criticism. Le cited anecdotes of people, notably American businessman Steven Paul Jobs (1955-2011) and American actor Christopher Ashton Kutcher (b. 1978), who sickened from excessive fruit intake.¹⁹ Le implicated fruits’ fructose in insulin resistance, pancreatic cancer, abnormal uric acid concentration, gout, metabolic disturbances, and heart disease. He cautioned that birds, bears, and people who eat primarily fruit lose weight, though dieters might welcome this prospect.²⁰ In contrast, Gundry faulted fruit consumption for overweight among gorillas (Gorilla gorilla and Gorilla beringei), chimpanzees (Pan troglodytes), bonobos (Pan paniscus), orangutans (Pongo pygmaeus, Pongo abelii, Pongo tapanuliensis, and Pongo hooijeri), and us.²¹ Beyond this critique, he blamed year-round fruit availability for human illnesses.

As the most strident critic, Gundry equated fruits with Wrigley Company candy Skittles, both being “the same poisonous stuff.”²² He did not specify the worst, though in hopes of finding an example to test, this paragraph notes that Newark, Delaware’s Produce Marketing Association listed bananas as the most eaten fruit in the United States in 2018.²³ Because Gundry allowed consumption of green bananas, this paragraph omits them in an effort to accommodate his predilections.²⁴

Instead, it references apples, the second most eaten fruit in 2018.²⁵ Comparison between Skittles and apples in Table 14.1 demonstrates the falsity of equating the two.²⁶ With only 12.8 percent as many calories by mass, apples furnish more fiber, protein, calcium, iron, zinc, magnesium, phosphorus, potassium, vitamins A, B, (thiamin or thiamine), B₂ (riboflavin), B, (nacin or nicotinic acid), B₅ (pantothenic acid), B₆ (pyridoxine), B₉ (folate, folic acid, or pteroylmonoglutamic acid), and K, less sodium, and fewer sugars. Calorie for calorie, apples have more of every nutrient—except sodium, Bj₂ (cobalamin), and D—than Skittles. Neither apples nor skittles have B_l2 and D.

TABLE 14.1

Nutrients in Skittles and Apples 100g