Our Unnatural “All-Natural” World

Much of what we eat today, often in large quantities, isn’t exactly what one could call all-natural. And if you really are what you eat, then we are already quite a different species. Bodies that for hundreds of thousands of years ate “all-natural” have been challenged to adapt fast to tidal waves of nachos and pizza.

Dental plaque provides a small window through which to view this massive evolutionary upheaval.1 Anyone who has been to the dentist knows how tough it is to remove plaque. Bad for you, but good for science. Its toughness makes plaque a great reservoir of data for bioanthropologists. Diet affects plaque, and by comparing the plaque in ancient and modern human teeth, scientists can infer what kinds of things we ate and what lived in our mouths. In the pre-Twinkie era, both early humans and our close relatives had mouths that were quite healthy. There are almost no examples of Neanderthal cavities. Paleolithic and Mesolithic human skulls are almost devoid of cavities.

As human diets began to modernize, as we began cooking and cleaning more of our daily foodstuffs, a strange thing happened: The bacterial colonies in our mouths became far less diverse. Hunter-gatherers from seven thousand years ago had far more microbial diversity in their mouths than did Stone Age agriculturalists.2 Bacteria that had coexisted and coevolved with our bodies and diets, that had adapted, were crowded out by a new environment, and our mouths became colonized by nastier bacteria. We further repopulated our mouths with the ever more widespread use of processed sugars. The incidence of cavities exploded. We began to suffer chronic oral disease, something that became most bothersome, and sometimes even deadly, in the pre-antibiotic, pre-brushing, pre-dentist era.

These days we need to do things no self-respecting Neanderthal would have considered: brush our teeth three times a day, floss, drink fluoridated water, fill cavities, and use dentures. (It’s worth noting that these practices are far from common, or necessary, in any wild animals.)

Our changing diet wasn’t just hard on our mouths. Average male height during the ninth to eleventh centuries was just below that of modern men. But the transition into the Middle Ages, the Enlightenment, and the Industrial Revolution was brutal. Disease, wars, serfdom, and filthy cities changed the morphology of men; by the 1700s, the average Northern European was 2.5 inches shorter than before and did not recover until the twentieth century.3

Evolving diets redesign our bodies in other ways. The average U.S. male increased his weight from 166 pounds in 1962 to 191 pounds by 2002. By 2011 we had gained, on average, a further five pounds.4 If we had observed this kind of generalized transformation in the bodies of a wild species, we would be shocked. But Darwin and his theories could have predicted much of this change; indeed, he saw hints of it in his studies of animal husbandry and how a species rapidly changed and adapted under human-directed breeding. So he would not have been terribly surprised observing the changed morphology of a gaggle of modern humans as they perambulate by with their monster soft drinks in hand.

In altering our desires and diets we did not just alter our own bodies, we also guided the evolution of broad swaths of nature. Think about it: just what exactly is “all-natural” food? Consider the humble potato. When conjecturing about the remote origin of his French fry, a teenager might blurt out Ireland or Idaho.5 Both would be wrong. Anyone who answered the old Inca Empire would be right.6

There’s good reason and precedent for humans to tinker with the evolution of our foodstuffs. Pre-Tiwanaku (the ancestors of the Inca), only about two hundred all-natural potato species existed, some of which were poisonous. Potatoes are related to deadly nightshade, which is why Indians would dunk tubers in a water-and-clay mixture; the clay would bind with and absorb the poisonous solanine and tomatine.7 In pre-Inca times, when food was quite scarce, eating potentially poisonous food was worth the risk; few crops grew on those steep, terraced hillsides, particularly edible plants that survived tropical and subtropical pests and insects.

Gradually the Peruvians’ ancestors learned how to pick, clean, cook, and de-poison potatoes, and learned how to breed them to meet their needs. By the time the Spaniards showed up to rape and pillage, the original two hundred varieties of all-natural potatoes had proliferated into more than three thousand varieties. Many of these you can still sample in Cuzco; its municipal markets are full of bright-yellow, purple, pink, dried, bright-white, starchy, fibrous, and crimson potatoes to snack on—a far cry from the dirty-looking brown, dowdy tubers we tend to see in Western supermarkets.8

And just what’s natural about having potatoes grow in Europe, anyway? They are in no way a native species.9 But boy, have they been useful. The Irish and Germans avoided famine for centuries thanks to this Incan import. However, they reverted from the cornucopia of Incan breed varieties toward a few standardized seeds—a costly error known as monoculturing. If you monoculture, and end up depending primarily on the “Irish Lumper” variety of potato, a single blight can wipe out a lot of plants and a lot of people, which is precisely what happened during the Gorta Mór, the Great Hunger, in Ireland.10 Lack of potato-disease resistance, and lack of alternative species, cost the country almost a quarter of its population; a million starved and almost a million emigrated. An equivalent disaster in the United States today would mean losing 80 million citizens. (Not that we have all learned this lesson . . . Just in case you don’t get bulletins from the Dairy Cattle Reproduction Council, it turns out that inbreeding of Holsteins, Jerseys, and Brown Swiss is at an all-time high.11 And Florida orange growers are also relearning the perils of monoculture as their crop withers away, a victim of a citrus plague.)12

A fun and ironic field trip involves going to “all-natural, organic” farmers’ markets and counting the number of completely unnatural, human-designed varieties of produce. Those wonderful, multicolored, oddly shaped, different-size heirloom tomatoes? Why, surely they’re “all-natural.” Well, not exactly. Tomatoes used to be small, green, and slightly poisonous. Summer farmers pride themselves on the variety of shapes, colors, sizes, and flavors they can coax into being. But this process is human-driven, not natural selection at work. Extreme tomato engineering begat some great specimens and some horrid options as well. Next time you bite into a gorgeously red but utterly tasteless big-box-store tomato slice, you can blame the lack of SIGLK2, the genetic switch that generates a tomato’s naturally sweet taste. It’s been turned off through breeding in most commercial varieties, in favor of that alluring bright-red skin.13

And while we’re on the topic of “all-natural” plants . . . How often do you ship your loved one true wildflowers? Odds are you tend to send weird-looking, colorful, fragrant, newly bred, long-lasting flowers unnaturally designed to delight the object of your affection. As you continue wandering through the “organic” market, how about those artisanal cheeses? Might these be the result of centuries of unnatural human tinkering too? When was the last time you found “wild cheese” in the forest? Even the animals that produce the basic ingredients for cheese are unnatural; should you truly seek a partly all-natural Brie or Camembert, it best be made with aurochs’ milk (which might be a little hard since the last aurochs died in Poland in the early 1600s).14 Or how about those beautiful “sheep’s milk” cheeses? Make sure they’re from a mouflon or Orkney, as all current domesticated varieties of sheep are the product of our unnatural meddling.15 We propagate hundreds of examples of useful nonnative species; otherwise there would be no corn in Europe, no horses in America. Britain alone hosts 1,800 nonnative plant species, which provide many staples at “all-natural” food markets.

Many nonnative species have hybridized with native species, enormously increasing variety and number. We have so modified, bred, molded, shaped, and distorted the “all-natural” to our own tastes and purposes that we forget, or take for granted, that much of what we live with, eat, and desire has evolved into something quite different from all-natural. In the words of ecologist Chris Thomas, “Nothing is entirely natural any longer.”16

Our eco-engineering and unnatural practices also lead to unnatural selection throughout the world’s oceans. Ever go snorkeling in the Mediterranean—say, near the Spanish, French, or Italian coasts, or the Greek Isles? Beautiful sea, some nice rocks, but no fish, coral, or much else that’s alive. If something moves, it tends to be very, very small. The sheer scale and breadth of our harvesting and its destructive effects has been staggering. We selected out almost all the fish.

And if you put on a scuba tank in January and take a brisk dive off Monterey, California, it’s clear, cold, and breathtakingly beautiful; forests of kelp sway as seals whiz by. You can pick up an octopus and watch birds dart past seeking fish thirty feet under. Countless starfish and anemones wave at large fish. But you don’t see any large sardine-bait balls. Which is strange for two reasons: This area is one of the most protected, and earliest-protected, eco-coastlines on the planet. Second, if you’d expected to see anything at all in what was once the “sardine capital of the world,” it would be lots and lots of sardines. That’s what fueled John Steinbeck’s novel Cannery Row. But today the town, despite great urban renewal and tourism focus, plays host to broken docks, few fishing jobs, and almost no sardines.

There are two parallel evolutionary systems at work off Monterey and in the Mediterranean. A natural one in which humans, the predators, decimate their prey—in this case fish. And an unnatural one in which humans use what they have learned to sometimes consciously redesign an ecosystem, often too late, to preserve and protect. If you are a big enough species and can get away with it, the first is normal and natural; the second is human and unnatural. A lot of species come back from the brink not because they adapt and adopt but because we will it; often we find them cute and they have a celebrity advocate.

Our attempts at eco-engineering and unnatural selection can also beget very rapid evolution.17 In an attempt to prevent massive factory boats from simply dragging and dredging the bottom of the waters and killing all creatures, or netting all things in the water regardless of their usefulness, various countries have put minimum size requirements in place for fishing. The theory: Let creatures grow till they can reproduce, then harvest them. Good idea, except that when you drive evolution in such a cut-and-dried way, in a matter of just a few generations the most successful survivors and reproducers are the runts.18 As more and more runts survive and reproduce, dwarf fish become the norm. This in turn changes not just the ecosystem of the specific semi-protected species but also those of its predators, symbionts, and co-dwellers.

We dominate so much that we can push unnatural selection (and rapid propagation) in some really unlikely environments. If you sail by the cold, foggy islands of Maine, in addition to fog, hidden rocks, and strong tides, you also have to cope with the extreme proliferation of colorful lobster buoys. Each year more appear. One would have thought that not a lobster would be left, but the opposite’s true. The past few years have seen an 80 percent increase in catch, and a halving of price. A combination of global warming, abundant food in traps, size limits, depletion of cod and other ground-feeding fish, and fisheries management has exploded the lobster population.19

One glimpse of how unnatural the world (and how important human-directed evolution) has become can be found while examining the patterns of species extinction. Humans are truly handy at wiping things out. Within a few thousand years of arriving in Australia, we killed every land animal, reptile, and bird weighing more than 220 pounds: fifty-five species, erased.20 The current rate of extinction is estimated to be 1,000 to 10,000 times higher than the normal rate of 1 to 5 species per year.21 Even the poor frog named in Darwin’s honor is near kaput.22 But again, while many species collapse because of our actions, we are also creating/driving/begetting an unprecedented number of new species to satisfy our hunger for food, beauty, and companionship.

Just over a decade ago some scientists predicted one-third to one-half of all land animals would go extinct due to human climate tinkering.23 Now some of these same folks witness and document a surge of new species entering the niches left by disappearing creatures.24 So while we are in the throes of a great extinction, human design and accident have also led to an enormous explosion in variety and varietals.25 Cal State’s Madhusudan Katti has documented how urban encroachment sometimes leads to the extinction of many native species, but he also found rapid adaptation and the flourishing of various species in their new urban environments; one-fifth of known bird species now also inhabit urban areas.26 Many birds develop a different song in order to cope with background urban noise; San Francisco’s white-crowned sparrows are now far noisier. Migration patterns also change. European blackcap warblers now just stay in southern England rather than flying off to Africa. Eating habits, weight, and appearance alter as birds adopt new behaviors and food becomes constantly available in outdoor cafés. Mammals also adapt; Drs. Emilie Snell-Rood and Naomi Wick took skulls from ten mammals and minutely measured the differences in brain size between those that lived in the country and those that lived in the Twin Cities. Two of the city species, white-footed mice and meadow voles, which have short reproductive cycles, grew bigger brains than their rural cousins.27 Apparently, at least for small mammals, it takes extra brains, guts, and street smarts to survive in the city.

Consider dogs. The closer a dog is to a coyote, or a wolf, the more “natural” it is.28 Curiously, one of the closest things to a wolf, in people’s homes, is a pet Afghan.29 These big, thin, hairy, energetic animals, originally bred to hunt tigers, are now shampooed, combed, ribboned, and pampered to show off in Manhattan. As we get further and further away from all-natural, we deliberately cultivate a crazy quilt of breeds, each designed for our own pleasure and purposes. Dog genetics is big business. We buy our pets for very specific purposes: to hunt, guard, look adorable in a Chanel bag, to make us look more macho. Buyer’s choice. Successful human-driven pet designs tend to get reinforced and reaffirmed rapidly, through rebreeding. Breeds or mixes that do not please us rarely re-wild, much less survive and thrive; instead, they either gradually die out, mongrelize, or end up euthanized in shelters. Often what we like and desire is completely unnatural; let a dozen Chihuahuas or Lhasa Apsos loose on the African plain and watch what happens. Likely not many, if any, would survive. So exactly what about today’s average dog is natural selection?30

As we engineer and groom Fido’s successors, we sometimes see how overdesign, inbreeding, and monoculture can have consequences. Some Dobermans lick their own flanks until they bleed.31 Many bull terriers never seem to stop chasing their tails, which may be due to a malfunctioning CDH2 gene (research on this trait may one day also help illuminate a source of OCD in humans).32 So we continue to tweak breeding, including tracking genes, in order to fix or create an even cuter set of Labradoodles. Dogs are a perfect example of the two new core drivers of modern evolution: unnatural selection and nonrandom mutation. Man’s best friend is a reflection of our genetic whims and desires. But of course it’s not just dogs we are changing, and it’s not just veggies, farms, and pets we alter; we are also fundamentally changing ourselves.