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)

Detailed imaging of runners’ hearts before and after races doesn’t find signatures of heart attacks

CT scans of preserved individuals show hardening of arteries similar to that seen in people today. (p. 14)

Medical imaging can add up to exposure similar to what nuclear power plant workers experience.

A portable method to quickly lower body temperature passes safety tests