HERDING HEMINGWAY'S CATS

A survey of recent research and thinking on genes.

What are genes, asks science writer Arney, and what do they do? “Genes are the things in your DNA that make your eyes blue, your belly bulge or your hair curl….Genetic knowledge has the power to save us,” she writes at the beginning of the book. Of course, it’s not nearly that simple, but by the end of the book, Arney has arrived at a simplified definition of a gene: “an inherited thing that does a thing.” In between, the author delivers an alluring tale of science at its most humble and probing, at least as practiced by the company of skeptics and scientific investigators. Genes are strings of DNA with instructions telling the cells to make various molecules—a string of building blocks to make a protein, for instance—that enable us to grow from a single cell into a baby. But the more we learn about genetic behavior, the murkier becomes our understanding. We know that genes can be switched on and off, but we also know the activator can be seriously distant from the genes producing a protein to endow a cell with individual characteristics. How do they communicate? There are 6 feet of DNA in every cell, jammed into the nucleus, “constantly on the move, writhing and wriggling like a nest of snakes.” If evolution is genetics and time, then this is natural selection at its most immediate and intimate. Arney delves into the importance of nature and nurture, as well as the epigenetic “impact of the environment on how this genetic information gets used.” Then come the bedeviling stochastic chemical interactions, the matters of chance “that the right things will come together at the right time.” With all the moving parts, she writes, genetics is “a statistical event rather than a guaranteed one.”

A robust, bouncy, pellucid introduction to DNA and genetics.