Junk DNA: A Journey through the Dark Matter of the Genome
by Nessa Carey
Columbia University Press, 2015 ($29.95)

When the human genome was first sequenced, 98 percent of it was dismissed as “junk” because it did not code for proteins and thus seemingly lacked purpose. Yet in recent years researchers have realized that these stretches of DNA are also important: for one thing, changes to them can lead to serious diseases. In chronicling what we know and what we wonder about junk DNA, biologist Carey makes an apt comparison to dark matter. Just as the universe appears to contain mass that we cannot see or understand and yet nonetheless exerts a pull on normal matter, the mysterious parts of our genome have a vital effect on the workings of more straightforward elements of DNA. In fact, far from being useless, genetic rubbish may be what differentiates humans from less advanced species.