by Sam Kean
Compare this to Albert Einstein, who always maintained that he thought in pictures, even about the fundamentals of space and time. Charles Darwin was of McClintock’s ilk. He included just one picture, of a tree of life, in the hundreds of pages of On the Origin of Species, and one historian who studied Darwin’s original notebook sketches of plants and animals acknowledged he was a “terrible drawer.”
she withdrew from science: If you’re interested in learning more about the reception of McClintock’s work, the scholar most responsible for challenging the canonical version of her life’s story is Nathaniel Comfort.
Chapter 6: The Survivors, the Livers
producing the very Cyclops: Most children born with cyclopia (the medical term) don’t live much past delivery. But a girl born with cyclopia in India in 2006 astounded doctors by surviving for at least two weeks, long enough for her parents to take her home. (No further information about her survival was available after the initial news reports.) Given the girl’s classic symptoms—an undivided brain, no nose, and a single eye—it was almost certain that sonic hedgehog had malfunctioned. And sure enough, news outlets reported that the mother had taken an experimental cancer drug that blocks sonic.
Maurice of Nassau: Prince Mo belonged to the dynastic House of Orange in the Netherlands, a family with an unusual (and possibly apocryphal) legend attached to its name. Centuries ago, wild carrots were predominantly purple. But right around 1600, Dutch carrot farmers, indulging in old-fashioned genetic engineering, began to breed and cultivate some mutants that happened to have high concentrations of the vitamin A variant beta carotene—and in doing so developed the first orange carrots. Whether farmers did this on their own or (as some historians claim) to honor Maurice’s family remains unknown, but they forever changed the texture, flavor, and color of this vegetable.
German biologist August Weismann: Although an undisputed brainiac and hall-of-fame biologist, Weismann once claimed—uproariously, given the book’s mammoth size—to have read On the Origin of Species in one sitting.
a fifth official letter to the DNAlphabet: A few scientists have even expanded the alphabet to six, seven, or eight letters, based on chemical variations of methylated cytosine. Those letters are called (if you’re into the whole brevity thing) hmC, fC, and caC. It’s not clear, though, whether these “letters” function independently or are just intermediate steps in the convoluted process by which cells strip the m from mC.
and Arctic huskies: The tale of the husky liver is dramatic, involving a doomed expedition to reach the South Pole. I won’t expand on the story here, but I have written something up and posted it online at http://samkean.com/thumb-notes. My website also contains links to tons of pictures (http://samkean.com/thumb-pictures), as well as other notes a little too digressive to include even here. So if you’re interested in reading about Darwin’s role in musicals, perusing an infamous scientific fraud’s suicide note, or seeing painter Henri Toulouse-Lautrec nude on a public beach, take a look-see.
carried the men home to the Netherlands: Europeans did not set eyes on the Huys again until 1871, when a party of explorers tracked it down. The white beams were green with lichen, and they found the hut sealed hermetically in ice. The explorers recovered, among other detritus, swords, books, a clock, a coin, utensils, “muskets, a flute, the small shoes of the ship’s boy who had died there, and the letter Barents put up the chimney for safekeeping” to justify what some might see as a cowardly decision to abandon his ship on the ice.
Chapter 7: The Machiavelli Microbe
the “RNA world” theory: Though RNA probably preceded DNA, other nucleic acids—like GNA, PNA, or TNA—might have preceded both of them. DNA builds its backbone from ringed deoxyribose sugars, which are more complicated than the building blocks likely available on the primordial earth. Glycol nucleic acid and peptide nucleic acid look like better candidates because neither uses ringed sugars for its vertebrae. (PNA doesn’t use phosphates either.) Threose nucleic acid does use ringed sugars, but again, sugars simpler than DNA’s. Scientists suspect those simpler backbones proved more robust as well, giving these ’NAs an advantage over DNA on the sun-scorched, semimolten, and oft-bombarded early earth.
viruses that infect only other parasites: This idea of parasites feasting on parasites always puts me in mind of a wonderful bit of doggerel by Jonathan Swift:
So nat’ralists observe, a flea
Hath smaller fleas that on him prey,
And these have smaller fleas that bite ’em,
And so proceed ad infinitum.
For my taste, a mathematician named Augustus De Morgan outdid even Swift on this theme:
Great fleas have little fleas upon their backs to bite ’em,
And little fleas have lesser fleas, and so ad infinitum.
And the great fleas themselves, in turn, have greater fleas to go on,
While these again have greater still, and greater still, and so on.
gave each cat an individual name: A sample: Stinky, Blindy, Sam, Pain-in-the-Ass, Fat Fuck, Pinky, Tom, Muffin, Tortoise, Stray, Pumpkin, Yankee, Yappy, Boots the First, Boots the Second, Boots the Third, Tigger, and Whisky.
despite their mounting distress: In addition to the $111,000 yearly, there were occasional unexpected costs, like when an animal lib person cut a hole in the fence to spring as many cats as possible. Jack said there were still so many cats around that they didn’t notice the dozens that escaped until a nun knocked on their door and asked if the cats climbing onto roofs throughout the neighborhood were theirs. Um, yes.
a plausible biological basis for hoarding cats: To be scrupulous: scientists have not yet run controlled studies on the correlation between Toxo levels in the brain and hoarding. So it’s possible that the link between Toxo, dopamine, cats, and hoarding could come to naught. Nor can Toxo explain everything about hoarding behavior, since people occasionally hoard dogs, too.
But most animal hoarders do hoard felines, and scientists involved in the Toxo studies find the link plausible and have said so publicly. They’ve simply seen too much evidence of how Toxo can change the hardwired behavior of rodents and other creatures. And regardless of how strong its influence turns out to be, Toxo still seeps dopamine into your brain.
to help Jack cope: Over the years, Jack and Donna have given many interviews about their lives and struggles. A few sources include: Cats I Have Known and Loved, by Pierre Berton; “No Room to Swing a Cat!,” by Philip Smith, The People, June 30, 1996; “Couple’s Cat Colony Makes Record Books—and Lots of Work!,” by Peter Cheney, Toronto Star, January 17, 1992; Current Science, August 31, 2001; “Kitty Fund,” Kitchener-Waterloo Record, January 10, 1994; “$10,000 Averts Ruin for Owners of 633 Cats,” by Kellie Hudson, Toronto Star, January 16, 1992; and Scorned and Beloved: Dead of Winter Meetings with Canadian Eccentrics, by Bill Richardson.
Chapter 8: Love and Atavisms
customize proteins for different environments in the body: In one extreme example, fruit flies carve up the RNA of the dscam gene into 38,016 distinct products—roughly triple the number of genes a fruit fly has. So much for the one gene/one protein theory!
practically a defining trait of mammals: Nature loves playing gotcha, and for almost everything you call a “unique” mammalian trait, there’s an exception: reptiles with a rudimentary placenta, for instance, or insects that give birth to live young. But in general, these are mammalian traits.
more extensive MHCs than other creatures: In humans, the MHC is often called the HLA, but since we’re focused on mammals here, I’ll use the general term.
the same extra nipples that barnyard sows have: Though best known for the telephone, Alexander Graham Bell had a keen interest in genetics and dreamed of breeding fitter humans. To learn more about biology, he bred sheep with extra nipples and studied the inheritance patterns.
tails contract involuntarily when children cough or sneeze: For more on human tails, see Jan Bondeson’s wonderful A Cabinet of Medical Curiositi
es. The book also has an astounding chapter on maternal impressions (like those in chapter 1), as well as many other gruesome tales from the history of anatomy.
simply have to round them up: The scientist did not end up winning funding for his research. And to be fair, he didn’t intend to spend all $7.5 million developing the gay bomb. Some of that money would have gone to, among other projects, a separate bomb that would have given the enemy epically bad breath, to the point of inducing nausea. No word on whether the scientist ever realized he could combine the two bombs into the most frustrating weapon in history.
Chapter 9: Humanzees and Other Near Misses
They’re that similar: In fact, this is how scientists first determined that chimps, not gorillas, are our closest living relatives. Scientists performed the first DNA hybridization experiments in the 1980s by mixing chimp, gorilla, and human DNA in a hot, steamy bath. When things cooled down, human DNA stuck to chimp DNA more readily than it did to gorilla DNA. QED.
should always have fewer mutations: This isn’t the place to even attempt to resolve this debate, but the scientists who first proposed the interbreeding theory have of course tried to counterrefute this supposed refutation. And the original scientists do have a point: in their paper announcing the theory way back in 2006, they actually anticipated this criticism about the X looking more uniform because of sperm production rates. Specifically, they noted that while X chromosomes should indeed look more alike for that reason, the X chromosomes they studied looked even more alike than this scenario could account for.
Naturally, the refuting scientists are busy countering the counterrefutations. It’s all very technical and a bit arcane, but exciting, given the stakes…
The Times story: In addition to its salacious details, the Times story also included this bizarre—and bizarrely egalitarian—quote: one scientist was convinced “that if the orang[utan] be hybridized with the yellow race, the gorilla with the black race, and the chimpanzees with the white race, all three hybrids will reproduce themselves.” What’s striking, especially for the time, is the insistence that all human beings, regardless of color, were kin to brutes.
the path to forty-six chromosomes a million years ago: To anticipate a question, yes, chromosomes can split, too, by a process called fission. In the primate line, our current chromosome numbers three and twenty-one were once yoked together into a team, and formed our longest chromosome for millions of years. Numbers fourteen and fifteen also split before the rise of great apes long ago, and both retain a funny, off-center shape today as a legacy. In some ways, then, the fourteen-fifteen fusion in the Chinese man was the ultimate genetic atavism, returning him to the ancestral, pre-ape state!
months of trench warfare: For more on Ivanov’s life, the most authoritative and least sensationalistic source is a paper by Kirill Rossiianov, in Science in Context, from the summer 2002 issue: “Beyond Species: Il’ya Ivanov and his experiments on cross-breeding humans with anthropoid apes.”
Chapter 10: Scarlet A’s, C’s, G’s, and T’s
“Until I tasted a bluebottle [fly]”: The supply of Buckland anecdotes is pretty much bottomless. One of his friends’ favorites was the time he and a stranger sitting across from him on a long train ride both fell asleep in their seats. Buckland woke up to find that some red slugs formerly nestled in his pockets had escaped, and were now sliming their way across his companion’s bald pate. Buckland discreetly exited at the next stop. Buckland also inspired his equally eccentric son Frank, who inherited his predilection for zoophagy and actually pioneered some of the more outré dishes the Buckland family ate. Frank had a standing agreement with the London Zoo that he got a shank of whatever animals died there.
Despite insulting Buckland, Darwin also indulged in zoophagy, even joining the Glutton Club at Cambridge, where he and companions dined on hawks, owls, and other beasts. On the Beagle voyage, Darwin ate ostrich omelets and armadillo roasted in its case, and after tucking into an agouti, a coffee-colored rodent that weighs twenty pounds, he declared it “the very best meat I ever tasted.”
For more details on Buckland’s life, work, family, and eccentricities, I highly recommend The Heyday of Natural History, by Lynn Barber, and Bones and Ochre, by Marianne Sommer.
He named it Megalosaurus: It later came to light that another scientist had discovered Megalosaurus bones in the 1600s, including a tree trunk of a femur. But he’d classified them as the bones of giant humans, a decision that Buckland’s work disproved. Strangely, two knobs on the end of that femur apparently traced out with Michelangelo-like verisimilitude the lower half of the human male package, inspiring a less-than-dignified moniker for the purported giants. Arguably, then, based on scientific priority in naming, the first known dinosaur species should be called Scrotum humanum. Buckland’s more proper name stuck, though.
thick, glowering brow we still associate with Neanderthals: The professor who identified the purported Cossack had decided the brow was shaped that way because the victim spent so many days furrowing it in pain. The professor apparently even believed the Cossack had scampered up sixty feet of sheer rock while mortally wounded, disrobed completely, and buried himself two feet deep in clay.
which lacks the tag: Lately, some DNA tags (a.k.a. DNA watermarks) have gotten rather elaborate, encoding names, e-mail addresses, or famous quotations—things nature couldn’t have inserted by chance. One research team headed by Craig Venter encoded the following quotes in A’s, C’s, G’s, and T’s, then wove them into a synthetic genome that they created from scratch and inserted into a bacterium:
To live, to err, to fall, to triumph, to recreate life out of life.
—JAMES JOYCE, A Portrait of the Artist as a Young Man
See things not as they are, but as they might be.
—From American Prometheus, a book about Robert Oppenheimer
What I cannot build, I cannot understand.
—RICHARD FEYNMAN (the words written on his blackboard at the time of his death)
Unfortunately Venter bungled the last quote. Feynman actually wrote, “What I cannot create, I do not understand.” Venter also ran into trouble with the Joyce quote. Joyce’s family (which controls his estate) is reputedly stingy about letting anyone (including a bacterium) quote him without express written permission.
millions of tons of vaporized rock per second: Compared to Mount Saint Helens, Toba spewed two thousand times more crap into the air. Of volcanoes worldwide, Toba is one of the few rivals to the giga-volcano currently smoldering beneath Wyoming, which will blow Yellowstone and everything around it sky-high someday.
Chapter 11: Size Matters
accidental, unrelated to his genius: Stephen Jay Gould gives a highly entertaining rendition of the story of Cuvier’s autopsy in The Panda’s Thumb. Gould also wrote a masterly, two-part article about the life of Jean-Baptiste Lamarck—whom we’ll meet in chapter 15—in his collection The Lying Stones of Marrakech.
the cost is a punier brain: Partly to determine how and why hobbits shrank, scientists are currently drilling a hobbit tooth to extract DNA. It’s a dicey procedure, since hobbits (unlike Neanderthals) lived in exactly the sort of tropical climate that degrades DNA the quickest. Attempts to extract hobbit DNA have always failed so far.
Studying hobbit DNA should help scientists determine if it really belongs in the genus Homo, a contentious point. Until 2010, scientists knew of only two other Homo species—Neanderthals, and possibly hobbits—still alive when Homo sapiens began overrunning the planet. But scientists recently had to add another to the list, the Denisovans (dun-EE-suh-vinz), named after a cave in cold Siberia where a five-year-old girl died tens of thousands of years ago. Her bones looked Neanderthal when scientists discovered them amid ancient layers of dirt and goat feces in 2010, but DNA extracted from a knucklebone shows enough distinctions to count as a separate line of Homo—the first extinct species discovered solely through genetic (not anatomical) evidence.
Traces of Denisovan DNA are fou
nd today in Melanesians, the people who originally settled the islands between New Guinea and Fiji. Apparently the Melanesians ran into Denisovans somewhere on the long haul from Africa to the South Seas and, as their ancestors had with Neanderthals, interbred with them. Today Melanesians have up to 8 percent non– Homo sapiens DNA. But beyond these clues, the Denisovans remain a mystery.
scattered the ashes: Want more? Galileo’s finger, Oliver Cromwell’s skull, and Jeremy Bentham’s entire decapitated head (including its freakishly shrunken skin) all went on posthumous display over the centuries. Thomas Hardy’s heart reportedly got eaten by a cat. Phrenologists stole Joseph Haydn’s head just before burial, and cemetery workers stole Franz Schubert’s “larvae-laden” hair while transferring him to a new grave. Someone even held a jar in front of Thomas Edison’s mouth during his death rattle to capture his last breath. The jar immediately went on exhibit in a museum.
I could probably go on for another page listing famous body parts that found new life—Percy Bysshe Shelley’s heart, Grover Cleveland’s cancerous jaw, supposed bits of Jesus’s foreskin (the Divine Prepuce)—but let me wrap up by pointing out that there are no legs to the persistent rumor that the Smithsonian Institution owns John Dillinger’s penis.
pack the cortex with neurons: The overall genetic algorithm to add bulk and density to the brain might be amazingly simple. The biologist Harry Jerison has proposed the following example. Imagine a stem cell whose DNA programs it to “divide thirty-two times, then stop.” If no cells die, you’d end up with 4,294,967,296 neurons. Now imagine tweaking that code to “divide thirty-four times, then stop.” This would lead to two more doublings, or 17,179,869,184 neurons.
The difference between 4.3 billion neurons and 17.2 billion neurons, Jerison notes, would be roughly the difference between the chimpanzee cortex population and the human cortex population. “The code may seem overly simple,” Jerison says, but “instructions that are significantly more complex may be beyond the capacity of genes to encode information.”