SAM KEAN

Except for certain moments - when cells are dividing, for instance - chromosomes don't form compact, countable bodies inside cells. Instead, they unravel and flop about, which makes counting chromosomes a bit like counting strands of ramen in a bowl.

America was probably Europe's equal scientifically by the end of World War I and certainly surpassed it after the chaos of World War II.

Brain surgery couldn't happen without the patient's own active voice to guide the work. The patient is part of the surgical team here, perhaps the most important part, and above all, that's what makes neurosurgery different.

If you had to sum up chemistry in one sentence, it might be this: Atoms need to have full shells of electrons to feel satisfied, and different elements steal, shed, or borrow different numbers of electrons to achieve a full shell.

In some sense, what you might have suspected from the first day of high-school chemistry is true: The periodic table is a colossal waste of time. Nine out of every 10 atoms in the universe are hydrogen, the first element and the major constituent of stars. The other 10 percent of all atoms are helium.

After about 1940, scientists generally stopped looking for elements in nature. Instead, they had to create them by smashing smaller atoms together.

Among physicists and chemists, cold fusion - nuclear fusion at close to room temperature - enjoys a reputation about on par with creationism.

Animal vision - including human vision - is so biased toward movement that we don't technically see stationary objects at all.

Brains, you see, vary a lot from person to person - they vary as much as faces do.

DNA is a 'thing' - a chemical that sticks to your fingers.

Even if we never cure a single disease, the Human Genome Project and other ventures will have been worth it.

Genes are like the story, and DNA is the language that the story is written in.

I'm kind of a sucker for the retro-diagnoses.

If studying the periodic table taught me nothing else, it's that the credulity of human beings for periodic table panaceas is pretty much boundless.

In 'The Violinist's Thumb,' I talk about the poignancy of cells leaking across the placenta into both the mother and the child.

Junk DNA - or, as scientists call it nowadays, noncoding DNA - remains a mystery: No one knows how much of it is essential for life.

Most mutations involve typos: Something bumps a cell's elbow as it's copying DNA, and the wrong letter appears in a triplet - CAG becomes CCG.

Most organisms have loads of junk DNA - less pejoratively, noncoding DNA - cluttering their cells.

Polonium is, frankly, pretty useless, and no country in the world except Russia bothered to refine it by the late 2000s.

Scientists have continued to tinker with different elements and have learned new ways to store and deliver energy.

The body tends to treat elements in the same column of the periodic table as equivalents.

The brain, which is plastic when young, must be exposed to certain sights early in life, or it will remain blind to those sights forever.

The inability to trace DNA to actual diseases has serious consequences. As does the opposite problem - not being able to trace diseases back to DNA.

We human beings are humane in part because we can look beyond our biology.

Without a functioning hippocampus, names, dates, and other information falls straight through the mind like a sieve.