The Triumph of Seeds (9 page)

F
IGURE
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. I
LLUSTRATION
© 2014
BY
S
UZANNE
O
LIVE
.

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.

F
IGURE
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. W
IKIMEDIA
C
OMMONS
.

“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.

B
efore 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.