An exciting update on human biology in the years since the initial description of the double helix structure of DNA in 1953. This is not a subject that popular writers have ignored, but Davis, a professor of immunology, refreshingly avoids the low-hanging fruit (life extension, designer babies) and digs into the actual science. While acknowledging the many miracles this new science will lead to (most of which will not occur in the immediate future), the author explores what contemporary scientists have learned and how they learned it. Davis emphasizes that many breakthroughs followed the development of new technology. For centuries, scientists could only examine living cells through the familiar light microscope, the magnification of which reached a limit in the 1870s before breakthroughs in the 20th century vastly increased its power. Years of work determined the structure of a single protein, insulin, and won Frederick Sanger a Nobel Prize in 1958. Today, machines do this in minutes. “It once took years and hundreds of millions of dollars to sequence a human genome,” writes Davis. “Now it takes a few hundred dollars, or less, and can be done in a single day.” The tedious process of counting and identifying living cells became much smoother with the invention of the flow cytometer. It’s easy to understand how the heart or kidney works by watching it in action but not the brain. Enter optogenetics, by which a genetically altered neuron fires when exposed to light. Following its tortuous path became easier with another advance that allowed scientists to give a cell a bright color without killing it. Davis, who writes accessibly and concisely, also examines a fairly new fascination, the gut: “There’s scarcely any state of human health or disease that hasn’t been linked with the [microbiome]. Variations have been associated with diseases as diverse as autism, asthma, multiple sclerosis, cancer and inflammatory bowel disease.” Further current research is revealing new ways that we can manipulate our resident bacteria for our benefit. Dazzling discoveries in expert hands.