God gives the nuts, but he does not crack them.
—German Proverb
In the late 1970s, the Peter Paul Manufacturing Company raised its suggested retail price for Almond Joy candy bars to twenty-five cents. But though this figure equaled my entire weekly allowance, I never regretted investing those wages in a confection the ad jingle summarized as “rich milk chocolate, coconut, and munchy nuts too!” At the time, it never occurred to me that my future career would reach this enviable moment: the opportunity to buy my favorite candy bars as a business expense. But a fact that escaped me then is extremely relevant now: from the first crunch of the roasted almond to the chewy sweetness of the chocolate and coconut finish, savoring an Almond Joy bar is an entirely seed-based experience. And while it’s tempting to chalk up Almond Joys to the same logic that Benjamin Franklin used for beer—“proof that God loves us”—there’s far more to their story. The seeds involved don’t just taste good; they demonstrate beautifully the incredible range of ways that a plant can pack lunch for its offspring.
An Almond Joy now costs eighty-five cents at our local drugstore, and I’ve paid more than a dollar for them at vending machines. But you still feel like you’re getting your money’s worth because each package actually contains two small bars. This gives buyers the opportunity to share with a friend or save a piece for later, though it’s unclear if anyone has ever done so. In my case, having two bars allowed me to eat one immediately and still have something left over to dissect. Cutting the bar in cross-section revealed its center of shredded coconut (from a pan-tropical palm), topped with almond (from an Asian tree in the rose family), and surrounded by a thin layer of chocolate (from a small New World rainforest tree). I took scrapes from each layer and prepared a microscope slide, but glancing at the package told me that none of these was the most dominant seed product in the bar. That honor rested with corn syrup, a sweetener derived from the seeds of a grass, maize, that is often used as a replacement for cane sugar (which, incidentally, also comes from a grass). But we already know from the last chapter that grasses are ubiquitous, and that their starch-filled seeds are easily transformed into sugars. The rest of the bar’s contents tell us why seeds have developed so many other ways to store energy, and why we should all be thankful that they have.
The milk chocolate coating contained cocoa butter as well as a dark, bitter slurry that candy makers refer to as cocoa liquor, cocoa mass, or simply chocolate. These products both come directly from the large cotyledons found in a mature cacao bean. Squeeze the bean in a hot press and more than half its mass drips out as cocoa butter, a fat with the important quality of being solid at room temperature but liquid above approximately 90 degrees Fahrenheit (32 degrees Celsius). Since the average body temperature clocks in at 98.6°F, chocolate, quite literally, melts in your mouth. Roasting and milling the beans produces cocoa liquor, which can be mixed with varying amounts of cocoa butter, milk, and accompanying sweeteners to give us the wide range of chocolate flavors available in any well-stocked candy aisle. Farther down on the ingredients list, I spotted cocoa powder, another familiar cacao product, which comes from grinding the cake of dry “nibs” left over after pressing the beans for butter.
In the wild, cacao beans reside inside the fleshy pods of a small, shade-loving tree native to forests of southern Mexico, Central America, and the Amazon. I often stumbled upon old cacao orchards in Costa Rica while searching for almendro seeds. I would glance up from a transect to find myself suddenly surrounded by their pods—bizarre, gourd-like fruits that sprouted directly from trunks and branches in varying shades of orange, purple, chartreuse, and hot pink. It’s no wonder that cacao caught the attention of the Mayans, Aztecs, and other early Americans, who developed a stimulating energy drink from the beans, and whose reverence for the species lives on in its genus name, Theobroma, “food of the gods.” It took Europeans and the rest of the world a few centuries to really acquire the taste, but cacao trees now grow everywhere from Guatemala to Ghana, Togo, Malaysia, and Fiji, and global chocolate sales exceed $100 billion annually. The average German consumes more than twenty pounds of the stuff every year, and in Britain people spend more money on candy than they do on bread and tea. Ecologically, the extravagance of a large, rich bean makes perfect sense. Like almendro or avocado, cacao seeds evolved to sprout and grow in a dark forest, where young seedlings need large energy reserves to survive. But nothing I saw in cacao plantations, botany textbooks, or candy bars explained why that energy had to come in the form of fat instead of starch.
I turned to the next ingredient on the Almond Joy list, coconut, from a seed that ranks among the world’s largest. Though familiar to anyone who has dreamed of palm trees and tropical beaches, the coconut is actually something of a mystery. Botanists call it cosmopolitan, a word that only came into common use in the nineteenth century, when global empires and fast sailing ships made it suddenly possible for an individual to become familiar with all parts of the world. For a plant, there can hardly be a greater compliment: so widespread and successful that no one is even sure where you came from. The coconut palm achieved this feat with fruits that function as massive, floating seeds. Each buoyant husk surrounds a single fist-sized kernel that is hollow except for a nutritious liquid known to health-food enthusiasts as “coconut water.” Whatever branding specialist coined that term cannot be blamed for shying away from the more accurate, technical description: acellular endosperm. But while “endosperm” might not sound catchy in an ad campaign, its market potential should not be underestimated. As a coconut seed matures, much of its liquid hardens into a solid endosperm called copra, the familiar white flesh that graces not only candy bars and cream pies but also Filipino stews, Jamaican breads, and South Indian chutneys. Squeeze water through that flesh, and you get coconut milk, an essential ingredient in curries and sauces throughout the coastal tropics. And with minimal processing, copra yields over half its volume in coconut oil, one of the top five vegetable fats in the world and a common additive in everything from margarine to sunscreen.
FIGURE 3.1. Coconut (Cocos nucifera). The seeds of the coconut palm, among the world’s largest, provide everything from thirst-quenching beverages to cooking oil, skin creams, and mosquito repellant. Dispersed throughout the coastal tropics by ocean currents and people, the origin of the species remains mysterious. ILLUSTRATION © 2014 BY SUZANNE OLIVE.
To a Hollywood set designer, coconuts provide a reliable fallback prop for any tropical situation. They’ve been featured as drinking cups in productions ranging from The Brady Bunch to Lord of the Flies, and as bra cups in King Kong, South Pacific, and the Elvis blockbuster Blue Hawaii. The Professor, a character in the 1960s sitcom Gilligan’s Island, famously used coconuts to build useful items like battery chargers and a lie detector. His inventions hardly seem exaggerated in light of the actual products made from coconuts, which include buttons, soap, charcoal, potting soil, rope, fabric, fishing line, floor mats, musical instruments, and mosquito repellant. This versatility led Malaysian islanders to name the coconut palm “tree of a thousand uses,” and in parts of the Philippines it’s simply “the tree of life.” But, for sheer ingenuity, nothing matches the bizarre ecology of the seed itself.
When a mature coconut drops from its mother tree, it usually hits sand. Tolerance to salt, heat, and shifting soil helps wild coconut palms thrive on the upper fringe of tropical beaches, from where high tides and storms regularly carry their seeds out to sea. Once afloat, a coconut can remain viable for at least three months, riding winds and currents for journeys of hundreds or perhaps thousands of miles. In that time, the endosperm continues to solidify, but enough coconut water remains to help the seed germinate when it finally washes up on some dry, sandy backshore. With its liquid endosperm keeping things moist inside, and the rich, oily copra providing energy, a young coconut can grow for weeks on end without any outside inputs. It’s not uncommon to see sprouted coconuts for sale as nursery stock in tropical markets, their bright young leaves already several feet tall.
The coconut palm’s seafaring adaptations set it apart, but still fail to explain why its seeds need such an unusually rich, oily lunch. After all, starches or cocoa butter would float, too, if you packed them inside that giant, fibrous husk. My investigation of the almond led quickly to the same basic question. Domesticated from a Central Asian cousin of peaches, apricots, and plums, the almond tree spread first to the Mediterranean and then around the world. People appreciated both its distinctive flavor and its nutritional value, because in addition to oil, an almond seed stores over 20 percent of its energy as pure protein. But why? What drove the evolution of such diverse seed nourishment strategies? Clearly, the answer to that question lay beyond what I could see in the remains of an Almond Joy. While I don’t need anyone’s help in eating candy bars, it was now apparent that I needed help understanding their biology. I decided it was time to contact someone whose name had cropped up again and again in my research, and whom more than one expert had described as a “god” in the world of seeds.
“That question?” he said, laughing. “I always ask our doctoral students that question in their qualifying exams. So far no one has come up with the answer!”
As a professor of botany at the University of Calgary and then the University of Guelph in Canada, Derek Bewley has been stumping students with seed questions for more than forty years. Luckily for everyone, his own research has provided many of the solutions. From development to dormancy to germination, the Bewley lab has explored all aspects of seed biology. But in spite of all these scholarly accomplishments, he told me his career had come as something of a surprise.
“Green was not a color where we lived,” Bewley explained, recalling his childhood in the “smoky, dirty old town” of Preston, Lancashire. “We lived in what you would call a row home. There was no yard in front, and all we had in the back was a bit of concrete before the alley started.” Life might have turned out quite differently if Bewley’s grandfather hadn’t retired to the country, where he raised tomatoes and bred award-winning chrysanthemums and dahlias. Visiting granddad and watering those greenhouses became one of Bewley’s “great joys as a child.” It sparked a passion for the green things of the world, and the seeds that produce them. That passion has produced hundreds of research papers and four books, including the seven-pound, eight-hundred-page Encyclopedia of Seeds, a constant companion to me in my own research. I knew I’d called the right person, but within a few minutes I also realized I wasn’t going to get a simple answer.
“The evolution of this doesn’t seem to be logical,” he began, and told me how starches, oils, fats, proteins, and other energy strategies seem to be scattered at random across the plant kingdom. No one technique stands out as more advanced than another, since many recently evolved species store energy in the same basic ways as ancient ones. To make matters worse, seeds usually contain several different kinds of energy, and a mother plant might change the proportions based on variations in rainfall, soil fertility, or other growing conditions. Nor do plants in similar environments or with similar life histories necessarily rely on the same strategy. Grass seeds are notoriously starchy, but one of the most common weeds in a grain field is the annual mustard called rape, whose tiny seeds produce copious quantities of canola oil. (Like “coconut water,” the name “canola” is a savvy branding invention. No one, presumably, felt very optimistic about marketing a product called “rape oil.”)
“There is one general rule,” he finally admitted. “Oil and fat-storing seeds have the most energy per weight. You get more punch from lipids than from a big pile of starch.” He also told me that seeds don’t usually access that energy until after germination. Most species keep enough sugars on hand to spark the embryo to life, and then start the more complex process of accessing their stored reserves. Starches convert to sugars relatively easily, but it takes a whole series of events to change protein, fat, or oil into a form useful for cell activity. Our own bodies work the same way, which is why you see competitors in Ironman triathlons downing bananas, cereal bars, or even jam sandwiches rather than slabs of bacon or cups of olive oil. In terms of seed evolution, this puts the emphasis on the newly sprouted plant and the resources its growing conditions will demand. But while that may explain why forest seeds like cacao and almond use fats and oils to fuel slow, steady growth in the shade, it does nothing to explain why mustard seeds in wide-open fields use the very same things to grow quickly. “There are exceptions,” Bewley said. We were talking on the phone, but I could almost see him shaking his head. “There are always exceptions.”
The British physicist William Lawrence Bragg once said that science is less about obtaining new facts than “discovering new ways of thinking about them.” Talking to Derek Bewley didn’t settle my questions about seed energetics with new information. Instead, it did so by reminding me of an important and fundamental truth about evolution itself. Charles Darwin once wrote, “Man may be excused for feeling some pride at having risen . . . to the summit of the organic scale.” This statement was fitting to its time, an era when any respectable Victorian gentleman naturally placed respectable Victorian gentlemen on the top rung of the evolutionary ladder. The trouble lies in the whole notion of evolutionary ladders and summits, the idea of a directional process climbing toward some notion of perfection. Of course, Darwin had a much more nuanced understanding of evolution, but this concept took root in our collective intellect and was perpetuated in cartoons, popular accounts, and even serious works of scholarship. The mind returns to it unconsciously, despite being surrounded by direct evidence to the contrary. If evolution progresses toward singularity, then how do we explain diversity—the 20,000 different grasses, the 35,000 dung beetles, the profusion of ducks, rhododendrons, hermit crabs, gnats, and warblers? Why are the most ancient life forms on the planet, bacteria and archaea, more diverse and prolific than all other species combined? Given time, evolution is much more likely to provide us with a multitude of solutions than it is to give us one ideal form.
My mistake lay in assuming that seeds had perfected the “best” methods for storing energy. I wanted to think that natural selection had eliminated the various possibilities until only one or at most several strategies remained, each adapted to a particular environment (forest, field, desert, etc.). The reality is far more complicated and far more interesting, like evolution itself—an endless and elegant articulation of the possible. Just as seeds can pack their lunches in different places (cotyledons, endosperm, perisperm, and so on), so, too, can that energy take many forms. If they offered only starch, seeds would no doubt still be successful in nature and we would still depend on them as a staple food. But without oils, fats, waxes, proteins, and other fuels, the seed habit might have lacked the versatility to dominate so many terrestrial ecosystems. And people would not be able to rely on peas, beans, and nuts for over 45 percent of global protein consumption. Nor could we enjoy most deep-fried foods, walk on linoleum floors, paint our houses, lubricate rocket and race-car engines, or marvel at the artwork of Vermeer, Rembrandt, Renoir, van Gogh, and Monet. All of these activities rely on seed-based oils. Even the most unusual energy sources in seeds turn out to have valuable human uses. The tagua nut palms of South America pack their lunches by thickening every cell wall within the endosperm, sometimes to the point of squeezing out the cells’ living contents. The resulting seeds are so hard they can be cut and polished for buttons and jewelry, carved into figurines, or used as a replacement for elephant ivory in the manufacture of chess pieces, dice, combs, letter openers, decorative handles, and fine musical instruments.
FIGURE 3.2. Darwin looks on in this cartoon parody from Punch magazine, December 6, 1881. Entitled “Man Is But a Worm,” it shows a spiraling progression of forms, from worm to monkey to evolution’s presumed pinnacle, a top-hatted Victorian gentleman. WIKIMEDIA COMMONS.
“Success is an endpoint in itself,” Bewley told me. The constant iterations of evolution ensure that new seed strategies will emerge, and anything that works is likely to stick around. In an odd way, this point took me right back to Almond Joy bars, and the catchy jingle that got me hooked on them in the first place: “Sometimes you feel like a nut; sometimes you don’t.” The advertisements featured “nutty” people eating Almond Joys while skydiving or riding horses backward, alternating with more straight-laced types eating Mounds, which is basically the same confection minus the almonds. Combined with the sort of irresistible tune that neurologist Oliver Sacks called a “brain worm,” these ads propelled both Almond Joy and Mounds into the top tier of American candy sales. But they also provide an important evolutionary lesson. When the goal is to satisfy a sweet tooth, tweaking the contents of a good recipe can provide more than one successful product. Similarly, when the goal is to nourish baby plants, many solutions are possible, and, like an inventive chef at a chocolate factory, evolution will eventually find them.
Before setting my Almond Joy experiment aside, I scanned the minor ingredients and noticed two more seed products worthy of mention: lecithin, from soybeans, and PGPR (polyglycerol polyricinoleate), from castor beans. In seeds, they’re both derivatives of storage fats, and lecithin plays an important role in mobilizing energy reserves. In chocolate bars, they’re added for smoothness and act as emulsifiers, helping to keep particles of sugar suspended in the cocoa butter. Soy lecithin shows up in all kinds of other products as well, from margarine and frozen pizza to asphalt, ceramics, and non-stick cooking spray. It’s even taken as a supplement for cardiovascular health, touted as an all-natural way to lower cholesterol.
After the emulsifiers, the list wrapped up with various preservatives, caramel coloring, and a warning about allergens, but I saw no sign of the last seed commodity I was looking for. Finding it required me to venture beyond my candy bar to one of its spin-off products: a trademarked Almond Joy Fudge-and-Coconut-Swirl, made by the Breyer’s Ice Cream Company. There, alongside the skim milk and artificial flavors, was guar gum, an extract whose strange properties affect everything from the texture of ice cream and gluten-free bread to the price of a motorcycle in northern India. Perhaps no single example better illustrates the wonderful variety of energies stored in seeds, and the unexpected ways in which they touch our lives.
Guar gum comes from a scruffy-looking cluster bean grown primarily on farms in Rajasthan, India’s, “Desert State.” Botanists put it with the endospermic legumes, a small group whose seeds lack the hefty cotyledons we know from beans, peanuts, and other members of the pea family. Instead, guar seeds store their energy in an endosperm loaded with highly branched carbohydrates. The diagrams in a chemistry textbook make those molecules look like maps of the London Underground, but to a baby guar plant in the Rajasthan Desert, they are a simple and essential adaptation.
“These tissues play a dual role,” Derek Bewley told me. “First, they can be broken down into food, the glucose that fuels plant growth. But they also provide a protective, moist layer surrounding the embryo.” He explained how the branched molecules inside a guar seed have an incredible ability to grab water and hold on tight. For a desert plant like guar, this trick transforms every rare cloudburst into a vital germination opportunity. It’s a habit that has evolved several times—locust beans can do it, and so can fenugreek—but always in places where the climate is dry.
Rajasthani farmers have grown guar for thousands of years, using it as a fodder for livestock and occasionally cooking up the green pods as a vegetable. But their fortunes began to change when people realized that guar-seed gum makes a palatable thickener eight times as effective as starch. Extracted and purified, guar gum soon found its way into everything from my Almond Joy ice cream to ketchup, yogurt, and instant oatmeal. By the year 2000, India’s guar exports to the food industry topped $280 million, but that was nothing compared to the boom that lay ahead.
The term fracking refers to an oil and natural gas extraction process known in the industry by its full name, hydraulic fracturing. It involves drilling boreholes deep into bedrock and using pressurized fluids to break apart and hold open gas-rich seams. When the fracked well is pumped out, the valuable hydrocarbons come along for the ride. Over the past decade, this once-obscure technology has grown into a multibillion-dollar global enterprise, opening up vast new deposits of shale gas and coal-bed methane. Economists expect it to effectively end North American reliance on foreign oil, fundamentally altering the world energy market. Drillers in the United States alone now frack an estimated 35,000 wells annually. And into each one of those wells they pump several million gallons of fracking fluid, a goopy combination of water, sand, acid, and chemicals all held together by one thing: guar gum.
In Rajasthan, the wholesale price for guar has risen by more than 1,500 percent in just a few years, sometimes doubling on a weekly basis. Subsistence farmers who once fed the stuff to their cows suddenly found they could sell it for enough to buy a television, then a motorcycle. Now, many are building new houses or taking family vacations abroad. Shortages of beans in 2011 and 2012 caused several drilling operations in North America to shut down, and the stock price of oil giant Halliburton Corporation fell by nearly 10 percent the week it warned shareholders that guar prices now accounted for nearly a third of its fracking costs and would “impact the company’s second quarter margins more than anticipated.” Tight supplies and the soaring price tag have forced many in the food industry to look elsewhere for thickeners. Not surprisingly, they’re finding alternatives in the seeds of other dry-country “endospermic” beans, including carob (from a Mediterranean locust tree), tara (from a coastal Peruvian shrub), and cassia (from the Chinese sicklepod). The fortunes of all three species—and their growers—are expected to surge on the coattails of the guar boom.
It’s doubtful that any oracle could have foreseen the great fortunes waiting to be made from grinding up guar seeds and pumping them underground. Indian crop reports as late as 2007 do not even list hydraulic fracturing as a potential market. The guar story shows how innovations in the evolution of seeds can drive innovations in their use. From a guar bean’s ability to retain water, we derive an industrial thickener, and suddenly seed energy is being used to extract fossil energy. For the oil industry, it represents something of a homecoming, since one of the most productive fracking sites in the world lies in the state of Pennsylvania, where the first commercially successful oil well was drilled in 1859. For seeds, drilling beneath Pennsylvania’s hilly countryside marks a far more ancient return.
If the goal of hydraulic fracturing were fossils instead of hydrocarbons, the wells tapping Pennsylvania’s Marcellus Shale would spout geysers of tiny snails and clamshells. They would not, however, produce a single seed. Because not only did those rocks form in a seabed devoid of plant life, they come from a time millions of years before seeds even evolved. Like any other new adaptation, seeds began as an oddity, bit players in a much larger drama. They appeared in the first years of the Carboniferous Period (360–286 million years ago), a time when most plants reproduced by spores. We know those spore plants best for what they left behind: vast swamp forests that fossilized as a shiny, black rock called coal. In Pennsylvania, coal deposits lie in the younger rocks directly on top of the shale, forming a layer so thick that it helped to fuel America’s Industrial Revolution and inspired geologists to name an entire period “the Pennsylvanian” in its honor. To glimpse the evolution of seeds, a fracker would simply need to drill shallower wells and start poking through the tailings.
Miners have always known they lived in a world of fossils, but scientists are starting to catch on, too. Recently, teams of paleobotanists—experts in fossil plants—have begun exploring and mapping old mine shafts, redefining our understanding of how and where seeds evolved. They’ve realized that the best way to understand a Carboniferous ecosystem is to walk through one, and the only place to do that is in a coal mine.