When Lewis Carroll sent Alice down the rabbit hole, she encountered a strange and twisted land with distortions of size and time. Some headache experts see something else — the possible ghosts of the author’s migraines, which can leave victims temporarily blinded, nauseated, hallucinatory, numb, unable to concentrate or seeking shelter from painful stings of light and sound. People with migraines travel between two worlds: one in which they are having a migraine and one in which they are not. “I’m very brave generally,” Tweedledum tells Alice, “only today I happen to have a headac... (p. 26)

A generation ago, the battle to survive a heart attack was usually won or lost in the emergency room. Medical advances have now enabled more patients to win that fight and go home from the hospital — but millions of them will face another threat in the years to come. The heart has a monstrous appetite for fuel as it goes about pumping 2,500 gallons of blood a day. During a heart attack, when an artery feeding heart muscle gets choked off, the heart’s oxygen supply is interrupted. If starved of oxygen for too long, a portion of the heart can die, never to revive. Instead, lifeless muscle w... (p. 26)

When it comes to the safety of dyeing food, the one true shade is gray. Artificial colorings have been around for decades, and for just about as long, people have questioned whether tinted food is a good idea. In the 1800s, when merchants colored their products with outright poisons, critics had a pretty good case. Today’s safety questions, though, aren’t nearly so black and white — and neither are the answers. Take the conclusions reached by a recent government inquiry: Depending on your point of view, an official food advisory panel either affirmed that food dyes were safe, questione... (p. 22)

Animals live long and prosper when eating from a menu that puts them just this side of starvation. So far, experiments with yeast, worms, flies, spiders, fish and rodents all have shown the antiaging power of severely restricting calories. And research in rhesus monkeys suggests similar benefits in primates: One study found that monkeys eating 30 percent less than their cage mates appeared to be protected from age-related diseases and had lower mortality 15 to 20 years later. At this moment, human volunteers at three different U.S. sites have given up 25 percent of normal daily calories to tes... (p. 22)

Mice aren’t known for their skill with complicated memory tricks, but they can usually recall their last meal. Once they happen upon food in a laboratory maze, they are pretty good at remembering the location from one trial to the next. In one recent study, though, half the mice got too confused to find their snacks. All the mice in two groups tested could remember the location of a new reward stashed in a vastly different place from an earlier one. But one group had trouble when the payoff lay just slightly off from a previous spot. Those mice had a good excuse, though: Their brains we... (p. 22)

Amino acids are the Legos of life — tiny bricks that snap together, forming the proteins on which every function of life depends. With rare exceptions, cells choose from just 20 kinds of Legos. But this is enough for human cells to assemble the more than 1 million proteins they need to function. A couple of decades ago, a few scientists decided that they wanted to play with more Legos. It began as an exercise in academic curiosity, a way to ask some of the Big Questions about life: Why just 20 amino acids? Why those 20? The researchers began to build artificial amino acids in the labora... (p. 18)

Throughout the leaner epochs of human history, when food supplies were unreliable, the species would not have survived without a way to hoard calories for later use. That is, without fat. Once a meal has supplied the body’s immediate energy needs, any unused fuel gets converted into long molecules called triglycerides, which are dispatched to fatty tissue where they wait for a signal that the body needs them.But in an era of high-calorie smorgasbords and 24/7 convenience, unused energy can just pile on year after year, a major reason why one-third of the U.S. adult population is struggling w... (p. 18)

In the germ world, fungi usually lack the flair of viruses or bacteria. To people with normal, healthy immune systems, a fungus will rarely show itself — even though you carry around a microscopic film of fungus on your hair and skin, and take in invisible clouds of fungal spores with each breath. While many other microbes prefer to make a living through disease and death, a fungus is often content to wait for its host to die of something else.In fact, throughout the history of civilization fungi have mostly been humans’ friends, providing the bounty of bread and beer, recycling trash and ... (p. 26)

Sidebar: Strife in the fast lane - Click to view Jamaican sprinter Usain Bolt secured his claim as the world’s fastest human in August when he ran 100 meters in 9.58 seconds, reaching a top speed of nearly 28 miles per hour. One day, no doubt, someone will sprint faster still. Perhaps by then, scientists may better understand why all speed records made have eventually been broken. Statisticians have long tried to calculate the upper limits of human speed. One recent estimate, published last year in the Journal of Experimental Biology, put the quickest possible time for 100 meters at 9.48... (p. 26)