The Canon (26 page)

Wine, beer, and other state-controlled spirits are the product of yeast cells feasting, and eating always requires chemical transformation: breaking apart molecules you find and using the parts and fuel to create the molecules you need. Yeast is a type of fungus, and while the fungal kingdom has an unusually catholic palate that may not always resonate with ours, the yeast strain that brews happens to share our love for sugar. If you add brewer's yeast cells to a vat of barley mash or well-stomped grapes, the yeast will latch onto the so-called simple sugars in the mix, "simple" meaning carbohydrate molecules that can't be broken down into still simpler carbohydrates. Simple sugars are the ones that taste sweet on the tongue and include glucose (which is the sugar that flows in your blood and serves as fuel to every cell), and fructose, the main sugar in fruit. (Put glucose and fructose together and you get sucrose, the table sugar you stir into coffee.) The two simpletons have the same chemical makeup, the same number of carbon, hydrogen, and oxygen atoms, differing only in how the atoms are arranged in three-dimensional space. No matter. The yeast will imbibe either, and will wrest energy from the sugar by breaking it down into two parts carbon dioxide and two parts ethyl alcohol, or ethanol. The carbon dioxide is the derivative that puts a little froth in the beverage, or, if the yeast has been added to bread dough rather than mash, that leavens its glutinous substrate into a puffy, oven-ready food item. The ethanol, of course, is what makes alcohol alcoholic, a leavener of mood and a lessener of sense. Ethanol is only one member in a large class of organic compounds
called alcohols, colorless and flammable chemicals found in a wide variety of settings. Your intestinal bacteria generate trace amounts of alcohol, and your muscle cells engage in fermentation whenever you push them to perform hard, fast, and anaerobically, i.e., without oxygen. The chemical byproducts of that fermentation can make a locker room smell oddly like a pub.

Regardless of source, all alcohols are accoutred with a hallmark hydroxyl group, a chemically reactive knob of oxygen and hydrogen that allows alcohol to wedge itself between comparatively bulkier molecules and help split them apart. Alcohol thus is widely used as a solvent in the manufacture of perfumes, dyes, pharmaceuticals, even children's cough syrup, and it makes for a pretty decent cleanser, too. Alcohol has low freezing and boiling points, allowing you to retrieve your designer liquor from the freezer and pour a neat shot right away, and to feel comfortable serving coq au vin to children or to Carrie Nation: by the time you take the pot off the stove, the alcohol in the wine sauce will have long since bubbled away.

Alcohol molecules can themselves be chemically transformed into sobriety. If you expose a bottle of wine to air and to the appropriate strain of aerobic bacteria—bacteria that need oxygen to feed and survive—the bacteria will pick up where yeast left off and break down the alcohol to water and acetic acid, or vinegar. As a molecule that dresses well with oil, vinegar has won its own measure of gastronomic fame at the salad bar; but for all its tart taste, vinegar lacks the inebriating vim of alcohol's hydroxyl accessory, and so could not addle a rabbit.

Fermentation is just a drop in the vast vat of reactive possibilities that surround us. Some chemical reactions occur easily and spontaneously while others won't bother unless you light a fire under their orbutts, or bury their starter parts underground and forget about them for a half a billion years. If you combine sodium and chlorine, poof, they'll react instantaneously, heatedly: Sodom meets Gomorrah, and we're left with a pillar of salt. And as the electrons of the participant ions assume their position in the crystal, they give up a bit of their verve, of their kinetic and potential energy. The total energy of the sodium chloride coalition is slightly less than that possessed by the sodiums and chlorides beforehand. Hence, the reaction that joins them is an exothermic one, a releaser of energy, in this case as heat, light, and the thrilling boom of a mini-explosion.

If, on the other hand, you stir together eggs, butter, flour, sugar, and other ingredients for a birthday cake, put the batter in a pan, and then realize halfway through the party that you never turned on the oven—
well, there's always Entenmann's. For the ingredients in the batter to react chemically and rearrange their bonds into the light, firm, moist, buoyant matrix of carbohydrates, fats, and proteins that we associate with cake requires energy. Baking a cake is an endothermic reaction, one that consumes heat rather than giving it out.

Then there are the chemical confrontations that start endothermically and end as a blast of hot air. The oxygen we breathe, the gas that makes up a fifth of our atmosphere, may be a lifegiver, but what a reactive zealot the molecule is. Oxygen combines with any substance it can, and in the merging steals electrons from its partner, changing the partner and singeing it and leaving it weaker than before. Oxygen is such a brilliant thief that the very act of electron piracy is called oxidation, even though other atoms and molecules can serve as oxidizers, too. Oxidation may be slow and steady, as it is when an iron bridge reacts with oxygen and starts to rust. Or it can be a matter of milliseconds: oxygen greets gasoline in the cylinder of a car engine, the mixture explodes, and you're on your way. Oxidative reactions are largely exothermic. A rusting bridge will emit modest amounts of heat, while the heat expelled by an internal combustion engine is great enough to warm a cat on a car hood hours after the engine has been cut. Combustion, though, generally requires an initial input of energy before it can turn self-sustainingly exothermic. A spark plug must spark the cylindrical courtship of oxygen and gasoline. A matchstick must be struck if it is to light in any way but figuratively. By scraping the match head on the appropriate surface, you heat it with friction. This heat is just what the sulfur, phosphorus, and other ingredients in the match need to combine in an unequivocally exothermic reaction. The heat from that sulfur-phosphorus collision in turn is enough to start oxidative combustion, the chemical confrontation between oxygen and a carbon-based substance—in this case, the wood shaft of the matchstick. Burning transforms the substrate into heat, light, carbon dioxide, and water vapor and will continue without further cajoling as long as there is carbon feed and oxygen greed.

Life is also a mix of endothermic and exothermic reactions, of gathering fuel and kindling, stacking the pieces with Boy Scout precision, striking the match, and feeling the burn. The body, after all, cannot afford to wait for the right chemistry to just happen. It doesn't have the luxury of sitting around for several million years like aluminum oxide, until the perfect confluence of geochemical events reinvents it as sapphire. Instead, the body must catalyze the reactions that it needs, pushing molecules together that might otherwise never find each other, and
then bask in the energetic results of the chemical coupling. Our cells are replete with enzymes, proteins that make reactions happen in predictable fashion, just as the spark plugs of an engine keep the gas in the cylinders combusting. Digestive enzymes release the energy in food, liver enzymes detoxify poisons, immune system enzymes neutralize microbes. We take in fuel to generate our catalysts: enzyme fabrication is an endothermic enterprise. Many of those enzymes then catalyze exothermic reactions, keep tens of thousands, tens of millions, of tiny home fires burning each day, and in just the right way.

In life, as in love, timing is key, and even the wristless wear watches. Plants that enlist faunal mobility to the cause of floral ubiquity must be sure to maximize the sweetness and softness of their submissions just when their seed is set to be spread. They want you, the frugivore, to consume the fruit at that moment, slough off the packaging metabolically, and then amble away to void the indigestible seeds on some distant patch of maiden soil. The strategic ripening of an apple, then, tenders an excellent example of controlled carnal glee, the stepwise igniting of tiny chemical blasts that blaze up as color and fragrance and succulent roundness, all begging you to come have a bite.

Apples begin budding on a tree right after the blossoms of spring have enticed insect pollinators to help fertilize a new crop of seeds. The blossoms fall away, and, in a grand, endothermic production—paid for by the tree's photosynthesizing leaves—a fruit bulges up around five pockets, or carpels, of seeds. Those seeds need time to mature, however, before they are capable of leaving the pod and sprouting new apple trees. An unripe apple therefore is a forbidding fruit, its cell walls thick and impermeable, its meat starchy, fibrous, and acidic, its outer skin plasticine green—common fruit shorthand for
CONSTRUCTION AREA: KEEP OUT
.

Give the apple and its seeds time, however, and they begin releasing ripening hormones, most notably ethylene. Ethylene is a compact molecular bundle of hydrogen and carbon atoms—a hydrocarbon—but its effects are large and fruitful. As ethylene molecules diffuse through the apple in the manner of a gas, they stimulate the activity of other enzymes, a platoon of fruit gentrifiers, coaches, carpenters, copy editors, wardrobe consultants, attitude adjusters. Some enzymes clip the starchy, complex carbohydrates into simple sugars, others help neutralize the acids, while still others break down the pectin glue between fruit cells and so help soften the fruit. As the cells become looser, sweeter, and more permeable, the fruit adopts an almost animal-like respiratory style, breathing in oxygen and exhaling carbon dioxide. The soaring
sugar content sucks in water from the stem, and the apple turns juicy. Its degraded molecules are now small enough to volatilize into the air and convey the distinctive aroma we perceive as apple. Enzymes in the skin help whisk away the green chlorophyll and generate in its stead bright, beguiling pigments of red or yellow, which can be seen from a distance and which are to a fruit-eating bird or mammal the visual equivalent of a dinner bell. Most of these chemical reactions are exothermic: in feel as in looks, the ripening fruit nearly glows. At last the apple can be plucked and sampled, and its warmth shared with someone you love.

A
S WE WERE
about to enter his office at the University of California's Museum of Vertebrate Zoology in Berkeley, Professor David Wake glanced off to the side and stopped abruptly.

"Wait a minute," he said. "I have to show you something. You'll love this. You'll absolutely love it." He darted over to a nearby shelf and retrieved from it a white plastic bucket with a lid on it. The lid had several holes punched through it. Professor Wake took off the lid and allowed me to peek.

"What the...?" I sputtered in confusion as I stared into the bucket. At the bottom was some sort of extraordinary, lizard-shaped doll, but unlike anything I'd seen at a zoo gift shop, Toys "R" Us, or even the Blarney Stone cocktail lounge near Penn Station. Its five-inch-long body was light and shimmering, like semitransparent flan, and obviously molded from an advanced gel-solid polymer. Its head was tinted teal, its dainty legs and the tip of its nose bore a hint of Necco pink, and its back and fat tail were sprinkled with patches of copper and lilac. I couldn't stop gawking. Was it a replica of an ancient reptile, driven extinct by its insupportable distribution of pastels? Was it a kind of visual pun, created by an artistically gifted scientist as wry commentary on the entire field of herpetology? Was it for sale, or should I just steal it when Professor Wake wasn't looking? And, hey, how did he get the thing to blink and flick its tail just now without pushing any buttons?

"Isn't it the most beautiful creature you've ever seen?" Wake said. "It's a gecko. A colleague just brought it back from the Mideast."

"Wait a minute," I said, or maybe squeaked. "You mean this is a real, live gecko?"

"Live and in color," Wake confirmed. "It does have an unearthly and somewhat comical quality to it, doesn't it? Like something from Dr. Seuss. Or don't you think it would be a perfect model for the computer animators over there at, what's it called, Pixar Studios? They wouldn't have to change a thing." He snapped the lid back in place and returned the bucket to the shelf.

No, I thought to myself. The gecko is gorgeous. The gecko gets you from the get-go. But the gecko that I later learned was appropriately, colloquially, called the Wonder Lizard looks far too fake to make it in cartoons.

The fake fakery is part of the take-home message here. In biology, you should never believe your disbelief. There are so many species that arouse one's suspicions, that look too-too: too stagy, too silly, too gothic, too pastiched, too elegant, too composed, too momentous, too perfect. Every time I see a toucan, I'm dubious. Its hulking yellow bill seems out of all proportion to the rest of its body and just barely attached to its face, as though the bird had stuck its beak into a giant banana and decided it liked the effect. And speaking of improbable schnozzes, let's not snub the star-nosed mole, a semiaquatic mole found throughout eastern North America. Ringing its snout are twenty-two fleshy, pinkish red, highly sensitive tentacles that, when fully extruded and wriggling about in search of food, look like a pinwheel of earthworms, or children's fingers poking up from below in a cheap but surprisingly effective horror movie. Surely the star-nosed mole didn't just happen; surely there is a disgruntled employee in some dank basement cubicle to blame.

In fact, when nineteenth-century European naturalists first encountered the duck-billed platypus of Australia and New Zealand—with its shuffling, lizardlike gait, its beady little eyes and slits for ears, its webbed feet and oar-shaped tail, and that outlandish, rubbery, bluish black Marx Brother of a mouthpiece, which doesn't even have the courtesy to quack—they were convinced the animal was a hoax. Not until several platypuses had been killed and dissected were the skeptics placated.

Amazing grace can also look fake: Two trumpeter swans facing each other, heads bowed, foreheads touching, each balletic neck curved into one half of a heart. You watch them move, and you could swear they're aware of the power of their beauty, as though they live to make you wistful, humble, and in awe of the divine. Or a male painted bunting, red of rump and nape, blue of head, green of backside—a prince of
primaries, a fistful of Matisse. I once saw a painted bunting on a log, and I couldn't believe how something so compact could fill my whole horizon.