WHAT'S GOTTEN INTO YOU

How the elements of the human body came to be.

In his debut book, writer and documentarian Levitt hits the ground running with news that a 150-pound human body contains 60 elements, including “enough carbon to make 25 pounds of charcoal, enough salt to fill a saltshaker, enough chlorine to disinfect several backyard swimming pools, and enough iron to make a three-inch nail.” On the open market, our body chemicals would bring about $2,000. To explain how they assembled into a human requires an explanation of life itself, which demands understanding the history of our planet. Many authors who write about our elemental makeup deliver this in an introductory chapter, but Levitt offers an entertaining history of the entire universe, paying most attention to humans in the introduction and final chapters. He keeps matters simple enough that science buffs will be satisfied and average readers will learn a great deal. The immense heat caused by the Big Bang permitted almost nothing to exist except the simplest elements, hydrogen and helium. After at least 100 million years of expansion and cooling, the two condensed into stars whose heat and pressure squeezed them into heavier elements—and even heavier ones when aging stars exploded. After more billions of years, galaxies and planetary systems formed, including the Earth 4.5 billion years ago. Scientists have no idea how life began, but Levitt’s page-turning account emphasizes how quickly it happened: within a few hundred million years. Life here and on other planets may be inevitable. Earthly life was bacterial for most of its existence. Plants came later, and they still rule the world, making up 80% of its biomass. Animals brought up the rear, eventually evolving into humans. The author notes that the process of completing this book “has been a continual source of wonder, stupefaction, exhilaration, and gratitude.” Readers will share those feelings.

Lively, illuminating popular science.