The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code (2 page)

DNA wasn’t done telling its stories to me. Some scientists have retroactively diagnosed Charles Darwin, Abraham Lincoln, and Egyptian pharaohs with genetic disorders. Other
scientists have plumbed DNA itself to articulate its deep linguistic properties and surprising mathematical beauty. In fact, just as I had crisscrossed from band to biology to history to math to social studies in high school, so stories about DNA began popping up in all sorts of contexts, linking all sorts of disparate subjects. DNA informed stories about people surviving nuclear bombs, and stories about the untimely ends of explorers in the Arctic. Stories about the near extinction of the human species, or pregnant mothers giving cancer to their unborn children. Stories where, as with Paganini, science illuminates art, and even stories where—as with scholars tracing genetic defects through portraiture—art illuminates science.

One fact you learn in biology class but don’t appreciate at first is the sheer length of the DNA molecule. Despite being packed into a tiny closet in our already tiny cells, DNA can unravel to extraordinary distances. There’s enough DNA in some plant cells to stretch three hundred feet; enough DNA in one human body to stretch roughly from Pluto to the sun and back; enough DNA on earth to stretch across the known universe many, many times. And the further I pursued the stories of DNA, the more I saw that its quality of stretching on and on—of unspooling farther and farther out, and even back, back through time—was intrinsic to DNA. Every human activity leaves a forensic trace in our DNA, and whether that DNA records stories about music or sports or Machiavellian microbes, those tales tell, collectively, a larger and more intricate tale of the rise of human beings on Earth: why we’re one of nature’s most absurd creatures, as well as its crowning glory.

Underlying my excitement, though, is the other side of genes: the trepidation. While researching this book, I submitted my DNA to a genetic testing service, and despite the price tag
($414), I did so in a frivolous state of mind. I knew personal genomic testing has serious shortcomings, and even when the science is solid, it’s often not that helpful. I might learn from my DNA that I have green eyes, but then again I do own a mirror. I might learn I don’t metabolize caffeine well, but I’ve had plenty of jittery nights after a late Coke. Besides, it was hard to take the DNA-submission process seriously. A plastic vial with a candy-corn orange lid arrived in the mail, and the instructions told me to massage my cheeks with my knuckles to work some cells loose inside my mouth. I then hocked into the tube repeatedly until I filled it two-thirds full of saliva. That took ten minutes, since the instructions said in all seriousness that it couldn’t be just any saliva. It had to be the good, thick, syrupy stuff; as with a draft beer, there shouldn’t be much foam. The next day I mailed the genetic spittoon off, hoping for a nice surprise about my ancestry. I didn’t engage in any sober reflection until I went to register my test online and read the instructions about redacting sensitive or scary information. If your family has a history of breast cancer or Alzheimer’s or other diseases—or if the mere thought of having them frightens you—the testing service lets you block that information. You can tick a box and keep it secret from even yourself. What caught me short was the box for Parkinson’s disease. One of the earliest memories I have, and easily the worst of those early memories, is wandering down the hallway of my grandma’s house and poking my head into the room where my grandpa, laid low by Parkinson’s, lived out his days.

When he was growing up, people always told my father how much he looked like my grandpa—and I got similar comments about looking like my old man. So when I wandered into that room off the hallway and saw a white-haired version of my father propped in a bed with a metal safety rail, I saw myself by extension. I remember lots of white—the walls, the carpet, the sheets, the open-backed smock he wore. I remember him pitched forward
to the point of almost tipping over, his smock loose and a fringe of white hair hanging straight down.

I’m not sure whether he saw me, but when I hesitated on the threshold, he moaned and began trembling, which made his voice quake. My grandpa was lucky in some ways; my grandma, a nurse, took care of him at home, and his children visited regularly. But he’d regressed mentally and physically. I remember most of all the thick, syrupy string of saliva pendulous on his chin, full of DNA. I was five or so, too young to understand. I’m still ashamed that I ran.

Now, strangers—and worse, my own self—could peek at whether the string of self-replicating molecules that might have triggered Parkinson’s in my grandfather was lurking in my cells, too. There was a good chance not. My grandpa’s genes had been diluted by my grandma’s genes in Gene, whose genes had in turn been diluted in me by Jean’s. But the chance was certainly real. I could face any of the cancers or other degenerative diseases I might be susceptible to. Not Parkinson’s. I blacked the data out.

Personal stories like that are as much a part of genetics as all the exciting history—perhaps more so, since all of us have at least one of these stories buried inside us. That’s why this book, beyond relating all the historical tales, builds on those tales and links them to work being done on DNA today, and work likely to be done tomorrow. This genetics research and the changes it will bring have been compared to a shifting ocean tide, huge and inevitable. But its consequences will arrive at the shore where we’re standing not as a tsunami but as tiny waves. It’s the individual waves we’ll feel, one by one, as the tide crawls up the shore, no matter how far back we think we can stand.

Still, we can prepare ourselves for their arrival. As some scientists recognize, the story of DNA has effectively replaced the old college Western Civ class as the grand narrative of human existence. Understanding DNA can help us understand where
we come from and how our bodies and minds work, and understanding the limits of DNA also helps us understand how our bodies and minds don’t work. To a similar degree, we’ll have to prepare ourselves for whatever DNA says (and doesn’t say) about intractable social problems like gender and race relations, or whether traits like aggression and intelligence are fixed or flexible. We’ll also have to decide whether to trust eager thinkers who, while acknowledging that we don’t understand completely how DNA works, already talk about the opportunity, even the obligation, to improve on four billion years of biology. To this point of view, the most remarkable story about DNA is that our species survived long enough to (potentially) master it.

The history in this book is still being constructed, and I structured
The Violinist’s Thumb
so that each chapter provides the answer to a single question. The overarching narrative starts in the remote microbial past, moves on to our animal ancestries, lingers over primates and hominid competitors like Neanderthals, and culminates with the emergence of modern, cultured human beings with flowery language and hypertrophied brains. But as the book advances toward the final section, the questions have not been fully resolved. Things remain uncertain—especially the question of how this grand human experiment of uprooting everything there is to know about our DNA will turn out.

C
hills and flames, frost and inferno, fire and ice. The two scientists who made the first great discoveries in genetics had a lot in common—not least the fact that both died obscure, mostly unmourned and happily forgotten by many. But whereas one’s legacy perished in fire, the other’s succumbed to ice.

The blaze came during the winter of 1884, at a monastery in what’s now the Czech Republic. The friars spent a January day emptying out the office of their deceased abbot, Gregor Mendel, ruthlessly purging his files, consigning everything to a bonfire in the courtyard. Though a warm and capable man, late in life Mendel had become something of an embarrassment to the monastery, the cause for government inquiries, newspaper gossip, even a showdown with a local sheriff. (Mendel won.) No relatives came by to pick up Mendel’s things, and the monks burned his papers for the same reason you’d cauterize a wound—to sterilize, and stanch embarrassment. No record survives of what they looked like, but among those documents were sheaves of
papers, or perhaps a lab notebook with a plain cover, probably coated in dust from disuse. The yellowed pages would have been full of sketches of pea plants and tables of numbers (Mendel adored numbers), and they probably didn’t kick up any more smoke and ash than other papers when incinerated. But the burning of those papers—burned on the exact spot where Mendel had kept his greenhouse years before—destroyed the only original record of the discovery of the gene.

The chills came during that same winter of 1884—as they had for many winters before, and would for too few winters after. Johannes Friedrich Miescher, a middling professor of physiology in Switzerland, was studying salmon, and among his other projects he was indulging a long-standing obsession with a substance—a cottony gray paste—he’d extracted from salmon sperm years before. To keep the delicate sperm from perishing in the open air, Miescher had to throw the windows open to the cold and refrigerate his lab the old-fashioned way, exposing himself day in and day out to the Swiss winter. Getting any work done required superhuman focus, and that was the one asset even people who thought little of Miescher would admit he had. (Earlier in his career, friends had to drag him from his lab bench one afternoon to attend his wedding; the ceremony had slipped his mind.) Despite being so driven, Miescher had pathetically little to show for it—his lifetime scientific output was meager. Still, he kept the windows open and kept shivering year after year, though he knew it was slowly killing him. And he still never got to the bottom of that milky gray substance, DNA.

DNA and genes, genes and DNA. Nowadays the words have become synonymous. The mind rushes to link them, like Gilbert and Sullivan or Watson and Crick. So it seems fitting that Miescher and Mendel discovered DNA and genes almost simultaneously in the 1860s, two monastic men just four hundred
miles apart in the German-speaking span of middle Europe. It seems more than fitting; it seems fated.

But to understand what DNA and genes really are, we have to decouple the two words. They’re not identical and never have been. DNA is a
thing
—a chemical that sticks to your fingers. Genes have a physical nature, too; in fact, they’re made of long stretches of DNA. But in some ways genes are better viewed as conceptual, not material. A gene is really information—more like a story, with DNA as the language the story is written in. DNA and genes combine to form larger structures called chromosomes, DNA-rich volumes that house most of the genes in living things. Chromosomes in turn reside in the cell nucleus, a library with instructions that run our entire bodies.

All these structures play important roles in genetics and heredity, but despite the near-simultaneous discovery of each in the 1800s, no one connected DNA and genes for almost a century, and both discoverers died uncelebrated. How biologists finally yoked genes and DNA together is the first epic story in the science of inheritance, and even today, efforts to refine the relationship between genes and DNA drive genetics forward.