No fruit pops up so frequently in Western art, literature, and everyday speech as the apple.
An apple (cunningly labeled “to the fairest”) started the Trojan War. (Odysseus, later struggling to get home from it, yearns for the garden he had as a child, populated by apple trees.) The Norse gods owed their immortality to apples. The Arabian Nights features a magic apple from Samarkand capable of curing all human diseases—predating the belief that an apple a day will keep the doctor away, a proverb that first appeared in print in 1866. Robert Frost, Emily Dickinson, Christina Rossetti, and Dylan Thomas all wrote poems about apples; and everyone from Caravaggio to Magritte painted them.
One place where the ubiquitous apple does not appear is in the Old Testament’s Book of Genesis. The original story of Adam, Eve, the snake, and the forbidden Tree of the Knowledge of Good and Evil mentions only an unspecified “fruit,” thus opening up centuries of debate over what the hapless First Couple actually ate. Various suggestions include everything from figs, grapes, and citrons to olives, apricots, bananas, pomegranates, and grapefruit. (Similar disagreements rage over probable locations of the Garden of Eden, which range from Turkey to Ohio, Mongolia, and the North Pole.)
The apple as Forbidden Fruit seems to have appeared in western Europe at least by the 12th century. Some researchers suggest that the apple got a bad rap from an unfortunate pun: the Latin malus means both “apple” and “evil,” which may have given early Christians ideas. A 1504 engraving by Albrecht Durer shows Adam and Eve with apples; and 16th-century paintings by Lucas Cranach and Titian show Adam and Eve under particularly tempting apple trees. Though Michelangelo’s Temptation and Fall on the Sistine Ceiling features forbidden figs, apples, increasingly, were held responsible for the Fall. By the 17th century, when Milton wrote Paradise Lost, the forbidden fruit was an Apple with a capital A.
Apples: Sour Enough to ‘Make a Jay Scream’
Apples, taxonomically, are members of Rosaceae, the Rose family, along with such other yummy edibles as pears, plums, peaches, cherries, strawberries, and raspberries. DNA analysis indicates that apples originated in the mountains of Kazakhstan, where the wild Malus sieversii—the many-times great-grandparent of Malus domestica, the modern domesticated apple—still flourishes.
There’s a lot to be said for domestication. Though Henry David Thoreau insisted that he much preferred the wild apple (“of spirited flavor”) to the civilized versions found in Massachusetts orchards, even he admitted that the occasional spirited bite was “sour enough to set a squirrel’s teeth on edge and make a jay scream.” The truth is that wild apples – grown from seeds—are generally pretty awful.
Apples are a victim of their own genetic creativity, a characteristic known to botanists as extreme heterozygosity. This ensures that an apple grown from seed won’t be anything like its parents. This is great for evolution, producing thousands of diverse apple varieties, adapted to every environment from North Dakota to New Zealand. For apple growers, though, intent on preserving selected favorites, the apple’s slippery genome is frustrating. In apples, the only guarantee of reproducibility is grafting, which is how our modern eating apples are propagated.
Johnny Appleseed, Spreading Booze Throughout America
But not by Johnny Appleseed. John Chapman of Leominster, Massachusetts—a.k.a. the apple-toting, tin-pot-hatted folk hero—condemned grafting as wicked, insisting that the only road to a good apple was seeds. Chapman collected seeds by the bushel from Pennsylvania cider mills and ferried them west, where he established apple nurseries in Ohio, Indiana, and Illinois, and distributed wildly random seedlings to settlers far and wide. The mouth-puckering results almost certainly went primarily into cider and applejack. These weren’t great eating apples. What Johnny Appleseed was disseminating was booze. Eventually this backfired, as temperance activists fingered the apple as a source of alcoholic sin and demanded that the morally upright burn their apple trees.
Recently the apple as forbidden fruit has been back in the news. Joe Davis, bio-artist attached to geneticist George Church’s lab at Harvard Medical School, is preparing to create an apple tree that is—literally—a Tree of Knowledge. Davis’s project aims to incorporate Wikipedia into the apple genome. For this purpose, he plans to use the world’s oldest known apple, a 4000-year-old variety of M. sieversii.
This isn’t as far-fetched as it sounds. Church and a number of other researchers have proposed that DNA may be the data storage venue of the future. A single droplet of DNA is capable of storing 700 terabytes of data – that’s the equivalent of 14,000 50-gigabyte Blu-Ray discs—and it’s impressively stable. Unlike magnetic tape that needs to be replaced every five years or so, DNA can survive for thousands. The trick is to convert data into binary code based on A, G, C, and T – the four nucleotide bases that make up DNA – and use the result as a blueprint to synthesize a DNA sequence. Davis plans to insert his Wikipedia-coded DNA into a bacterium capable of transferring its genome into an apple cell. This won’t change the taste, smell, or appearance of the apple, but each treated fruit will carry, hidden among its genes, a chunk of extra info—say, the Wikipedia entry on apple trees, snakes, Genesis, or applesauce.
Apples: The Fruit of Knowledge
All of Wikipedia can’t fit into one handy apple. Each tiny bacterial carrier can only cope with a few thousand words—which means the whole of Wikipedia, some two and a half billion words long, may require an entire forest of apple trees. (One critic guesses 666,000 trees.) And eating such an apple, sadly, won’t make any of us more knowledgeable. Retrieving the info from apple DNA will require a DNA sequencer and some decoding software. On the other hand, this may be just as well. Most M. sieversii varieties are what apple growers refer to as “spitters”—because the common response to the first mouthful is to spit it out, fast.
The 50-acre orchard at USDA’s Plant Genetics Resources Unit in Geneva, New York, has what may be the world’s largest collection of apple trees—some 2500 different varieties from all over the world. Among the latest additions are varieties of M. sieversii, the apple’s ancient ancestor from Asia, laden with beneficial genes not found in our modern and monotonous apple crop. Whereas a century ago, Americans grew thousands of varieties of apples, nowadays we’re down to just a handful, among them McIntosh, Jonathan, and Red Delicious—which last, a lot of people argue, may be red, but it isn’t exactly delicious. Genetic uniformity in crops seldom pays off, and the American apple—attacked by pests on all sides—now needs a battery of chemicals in order to survive. Ancestral genes may give our apples the resistance and versatility they need—to say nothing of a new battery of flavors, colors, and shapes that we’ve forgotten apples ever had.
When it comes to information, M. sieversii doesn’t need Wikipedia.
Luckily for us, it already has plenty.
This story is part of National Geographic’s special eight-month Future of Food series.
- Church, George M., Yuan Gao, Sriram Kosuri. Next-Generation Digital Information Storage in DNA. Science 28, September 2012.
- House, Patrick. Object of Interest: The Twice-Forbidden Fruit. New Yorker, May 2014.
- Pollan, Michael. Breaking Ground: The Call of the Wild Apple. New York Times, 5 November, 1998.
- Wilensky-Lanford, Brook. Paradise Lust: Searching for the Garden of Eden. Grove Press, 2011.