The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code (43 page)

Though advanced science, epigenetics actually revives an ancient debate in biology, with combatants who predate Darwin—the Frenchman Jean-Baptiste Lamarck and his countryman, our old friend Baron Cuvier.

Just as Darwin made his name studying obscure species (barnacles), Lamarck cut his teeth on
vermes. Vermes
translates to “worms” but in those days included jellyfish, leeches, slugs, octopuses, and other slippery things that naturalists didn’t stoop to classify. Lamarck, more discriminating and sensitive than his colleagues, rescued these critters from taxonomic obscurity by highlighting their unique traits and separating them into distinct phyla. He soon invented the term
invertebrates
for this miscellanea, and in 1800 went one better and coined the word
biology
for his whole field of study.

Lamarck became a
biologist
through roundabout means. The moment his pushy father died, Lamarck dropped out of seminary school, bought a creaky horse, and, just seventeen years old,
galloped away to join the Seven Years’ War. His daughter later claimed that Lamarck distinguished himself there, earning a battlefield promotion to officer, though she often exaggerated his achievements. Regardless, Lt. Lamarck’s career ended ignominiously when his men, playing some sort of game that involved lifting Lamarck by his head, injured him. The military’s loss was biology’s gain, and he soon became a renowned botanist and vermologist.

Not content with dissecting worms, Lamarck devised a grandiloquent theory—the first scientific one—about evolution. The theory had two parts. The overarching bit explained why evolution happened period: all creatures, he argued, had
“inner urges” to “perfect” themselves by becoming more complex, more like mammals. The second half dealt with the mechanics of evolution, how it occurred. And this was the part that overlaps, conceptually at least, with modern epigenetics, because Lamarck said that creatures changed shape or behavior in response to their environment, then passed those acquired traits on.

Jean-Baptiste Lamarck devised perhaps the first scientific theory of evolution. Though mistaken, his theory resembles in some ways the modern science of epigenetics. (Louis-Léopold de Boilly)

For instance, Lamarck suggested that wading shorebirds, straining to keep their derrieres dry, stretched their legs microscopically farther each day and eventually acquired longer legs, which baby birds inherited. Similarly, giraffes reaching to the tippity-tops of trees for leaves acquired long necks and passed those on. It supposedly worked in humans, too: blacksmiths, after swinging hammers year after year, passed their impressive musculature down to their children. Note that Lamarck didn’t say that creatures
born
with longer appendages or faster feet or whatever had an advantage; instead creatures worked to develop those traits. And the harder they worked, the better the endowment they passed to their children. (Shades of Weber there, and the Protestant work ethic.) Never a modest man, Lamarck announced the “perfecting” of his theory around 1820.

After two decades of exploring these grand metaphysical notions about life in the abstract, Lamarck’s actual physical life began unraveling. His academic position had always been precarious, since his theory of acquired traits had never impressed some colleagues. (One strong, if glib, refutation was that Jewish boys still needed circumcising after three millennia of snip-snipping.) He’d also slowly been going blind, and not long after 1820, he had to retire as professor of “insects, worms, and microscopic animals.” Lacking both fame and income, he soon became a pauper, wholly reliant on his daughter’s care. When he died in 1829, he could only afford a “rented grave”—meaning his
vermes
-eaten remains got just five years’ rest before they were dumped in the Paris catacombs to make room for a new client.

But a bigger posthumous insult awaited Lamarck, courtesy of the baron. Cuvier and Lamarck had actually collaborated when they’d first met in postrevolutionary Paris, if not as friends then as friendly colleagues. Temperamentally, though, Cuvier was 179 degrees opposed to Lamarck. Cuvier wanted facts, facts, facts, and distrusted anything that smacked of speculation—basically all of Lamarck’s late work. Cuvier also rejected evolution outright. His patron Napoleon had conquered Egypt and lugged back tons of scientific booty, including murals of animals and mummies of cats, crocodiles, monkeys, and other beasts. Cuvier dismissed evolution because these species clearly hadn’t changed in thousands of years, which seemed a good fraction of the earth’s lifetime back then.

Rather than limit himself to scientific refutations, Cuvier also used his political power to discredit Lamarck. As one of the many hats he wore, Cuvier composed eulogies for the French scientific academy, and he engineered these
éloges
to ever-so-subtly undermine his deceased colleagues. Poisoning with faint praise, he opened Lamarck’s obit by lauding his late colleague’s dedication to vermin. Still, honesty compelled Cuvier to point out the many, many times his dear friend Jean-Baptiste had strayed into bootless speculation about evolution. Baron Cuvier also turned Lamarck’s undeniable gift for analogies against him, and sprinkled the essay with caricatures of elastic giraffes and damp pelican bums, which became indelibly linked to Lamarck’s name. “A system resting on such foundations may amuse the imagination of a poet,” Cuvier summed up, “but it cannot for a moment bear the examination of anyone who has dissected the hand, the viscera, or even a feather.” Overall, the “eulogy” deserves the title of “cruel masterpiece” that science historian Stephen Jay Gould bestowed. But all morality aside, you do have to hand it to the baron here. To most men, writing eulogies would have been little more than a pain in the neck. Cuvier saw that he could parlay
this small burden into a great power, and had the savviness to pull it off.

After Cuvier’s takedown, a few romantic scientists clung to Lamarckian visions of environmental plasticity, while others, like Mendel, found Lamarck’s theories wanting. Many, though, had trouble making up their minds. Darwin acknowledged in print that Lamarck had proposed a theory of evolution first, calling him a “justly celebrated naturalist.” And Darwin did believe that some acquired characteristics (including, rarely, circumcised penises) could be passed down to future generations. At the same time, Darwin dismissed Lamarck’s theory in letters to friends as “veritable rubbish” and “extremely poor: I got not fact or idea from it.”

One of Darwin’s beefs was his belief that creatures gained advantages mostly through inherent traits, traits fixed at birth, not Lamarck’s acquired traits. Darwin also emphasized the excruciating pace of evolution, how long everything took, because inborn traits could spread only when the creatures with advantages reproduced. In contrast, Lamarck’s creatures took control of their evolution, and long limbs or big muscles spread everywhere lickety-split, in one generation. Perhaps worst, to Darwin and everyone else, Lamarck promoted exactly the sort of empty teleology—mystical notions of animals perfecting and fulfilling themselves through evolution—that biologists wanted to banish from their field forever.
^*

Equally damning to Lamarck, the generation after Darwin discovered that the body draws a strict line of demarcation between normal cells and sperm and egg cells. So even if a blacksmith had the tris, pecs, and delts of Atlas himself, it doesn’t mean squat. Sperm are independent of muscle cells, and if the blacksmith’s sperms are 98-milligram weaklings DNA-wise, so too might his children be weaklings. In the 1950s, scientists reinforced this idea of independence by proving that body cells
can’t alter the DNA in sperm or egg cells, the only DNA that matters for inheritance. Lamarck seemed dead forever.

In the past few decades, though, the
vermes
have turned. Scientists now see inheritance as more fluid, and the barriers between genes and the environment as more porous. It’s not all about genes anymore; it’s about expressing genes, or turning them on and off. Cells commonly turn DNA off by dotting it with small bumps called methyl groups, or turn DNA on by using acetyl groups to uncoil it from protein spools. And scientists now know that cells pass those precise patterns of methyls and acetyls on to daughter cells whenever they divide—a sort of “cellular memory.” (Indeed, scientists once thought that the methyls in neurons physically recorded memories in our brains. That’s not right, but interfering with methyls and acetyls can interfere with forming memories.) The key point is that these patterns, while mostly stable, are not permanent: certain environmental experiences can add or subtract methyls and acetyls, changing those patterns. In effect this etches a memory of what the organism was doing or experiencing into its cells—a crucial first step for any Lamarck-like inheritance.

Unfortunately, bad experiences can be etched into cells as easily as good experiences. Intense emotional pain can sometimes flood the mammal brain with neurochemicals that tack methyl groups where they shouldn’t be. Mice that are (however contradictory this sounds) bullied by other mice when they’re pups often have these funny methyl patterns in their brains. As do baby mice (both foster and biological) raised by neglectful mothers, mothers who refuse to lick and cuddle and nurse. These neglected mice fall apart in stressful situations as adults, and their meltdowns can’t be the result of poor genes, since biological and foster children end up equally histrionic. Instead the aberrant methyl patterns were imprinted early on, and as neurons kept dividing and the brain kept growing, these patterns
perpetuated themselves. The events of September 11, 2001, might have scarred the brains of unborn humans in similar ways. Some pregnant women in Manhattan developed post-traumatic stress disorder, which can epigenetically activate and deactivate at least a dozen genes, including brain genes. These women, especially the ones affected during the third trimester, ended up having children who felt more anxiety and acute distress than other children when confronted with strange stimuli.

Notice that these DNA changes aren’t
genetic,
because the A-C-G-T string remains the same throughout. But epigenetic changes are de facto mutations; genes might as well not function. And just like mutations, epigenetic changes live on in cells and their descendants. Indeed, each of us accumulates more and more unique epigenetic changes as we age. This explains why the personalities and even physiognomies of identical twins, despite identical DNA, grow more distinct each year. It also means that that detective-story trope of one twin committing a murder and both getting away with it—because DNA tests can’t tell them apart—might not hold up forever. Their epigenomes could condemn them.

Of course, all this evidence proves only that body cells can record environmental cues and pass them on to other body cells, a limited form of inheritance. Normally when sperm and egg unite, embryos erase this epigenetic information—allowing you to become
you,
unencumbered by what your parents did. But other evidence suggests that some epigenetic changes, through mistakes or subterfuge, sometimes get smuggled along to new generations of pups, cubs, chicks, or children—close enough to bona fide Lamarckism to make Cuvier and Darwin grind their molars.

The first time scientists caught this epigenetic smuggling in action was in Överkalix, a farming hamlet in the armpit between
Sweden and Finland. It was a tough place to grow up during the 1800s. Seventy percent of households there had five or more children—a quarter, ten or more—and all those mouths generally had to be fed from two acres of poor soil, which was all most families could scrape together. It didn’t help that the weather above sixty-six degrees north latitude laid waste to their corn and other crops every fifth year or so. During some stretches, like the 1830s, the crops died almost every year. The local pastor recorded these facts in the annals of Överkalix with almost lunatic fortitude. “Nothing exceptional to remark,” he once observed, “but that the eighth [consecutive] year of crop failure occurred.”

Not every year was wretched, naturally. Sporadically, the land blessed people with an abundance of food, and even families of fifteen could gorge themselves and forget the scarce times. But during those darkest winters, when the corn had withered and the dense Scandinavian forests and frozen Baltic Sea prevented emergency supplies from reaching Överkalix, people slit the throats of hogs and cows and just held on.