The Gene: An Intimate Historyby Siddhartha MukherjeeScribner, 2016Siddhartha Mukherjee's big and utterly captivating new book, The Gene: An Intimate History, acts among other things as a perfect companion to his Pulitzer Prize-winning earlier book The Emperor of All Maladies. The earlier book told the story of human cells run amok, warping their normal functions into the horrifying array of cancers that afflict mankind. The new book maps the broader universe in which so many cancers manifest: the “intimate” geographies of the human genetic makeup.The books are further united by the hugely impressive rhetorical gifts of their author. Mukherjee is that rare kind of science writer whose prose is unfailingly inviting despite the often fiercely complex nature of his subjects. In The Gene, he takes his readers through the entire long history of the study of genetics, from the groping millennia of trial-and-error animal stock breeding to the landmark discoveries of Mendel, Darwin, Crick, and the pioneers who mapped the human genome. He sketches personalities with a novelist's skill and economy, and he mixes liberal amounts of his own family history with an honesty that's both disarming and illuminating, the most effective reminder possible that the gene is the heart of what we all share in common.Since his book is written for a 21^st century audience (and since its publisher clearly has an eye cocked toward the bestseller lists that have always favored this author), Mukherjee must work into his larger narrative a good deal of backgrounding in the principles of the biological sciences. And naturally the cornerstone of this foundation is the concept of evolution by means of natural selection. Darwin himself, though ignorant of the means or methods of heredity, saw instantly that it was the key to his theory, and Mukherjee's contextualizations on the subject are deft:

Natural selection must choose the mutations that confers the best fitness to the organism and thereby allows that mutation to become increasingly common in the gene pool. But in this scheme, neither mutation nor evolution has an intentionality or directionality. In nature, the engine that drives genetic alteration has no one in its driver's seat. The “watchmaker” of evolution, as Richard Dawkins reminds us, is inherently blind.

The larger questions raised by any long study of human genetics come up all through this book, and one of those questions becomes more pressing with each new discovery: how much of day-to-day human life is determined by genes? The popular conceptions of this question are not only timid – that genetics plays a distinctly background role to environment and learning – but usually ill-informed – that acquired traits are inheritable, etc. And here again, Mukherjee excels at laying the groundwork:

Anyone who doubts that genes can specify identity might well have arrived from another planet and failed to notice that the humans come in two fundamental variants: male and female. Cultural critics, queer theorists, fashion photographers, and Lady Gaga have reminded us – accurately – that these categories are not as fundamental as they might seem, and that unsettling ambiguities frequently lurk in their borderlands. But it is hard to dispute three essential facts: that males and females are anatomically and physiologically different; that these anatomical and physiological differences are specified by genes; and that these differences, interposed against cultural and social constructions of the self, have a potent influence on specifying our identities as individuals.

If anything, The Gene itself is still too timid on the question of genetic identity, still too willing to ascribe to circumstance and random pathology things that may very well be purely attributable to genes. For all the advances the last three decades have seen in genetic analysis and manipulation, this is still a frontier inquiry. The Gene perfectly captures the sprawling potential, the sheer excitement, of that ongoing quest. Like its predecessor, it's as masterpiece of informed popular science-writing.