Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond

“We must always be prepared to be surprised,” writes Princeton geoscientist Onstott as he ventures into the world of “subterranauts,” creatures that inhabit underground regions that were previously thought inhospitable to life. He exhaustively details some of the expeditions that are leading scientists to overturn the dogma that all life needs the sun. Chemolithoautotrophs, for example, do not; they create energy by splitting minerals. Such extremophiles offer clues to what extraterrestrial life might be like, so Onstott travels beneath Earth’s hottest spots (Africa) and coldest spots (the Arctic) to learn more about them. He colorfully describes these almost primordial worlds: mines where one can find “mushrooms the size of hubcaps,” an Arctic tunnel in which hangs “one ice chandelier after another,” and caves that feature biofilms wafting across underground lakes in “massive rafts” or hanging off walls like a living Jackson Pollock painting. A colleague’s discovery of a microscopic worm a mile below earth was “like finding Moby Dick swimming around in Lake Ontario”—a discovery with “enormous implications.” Onstott himself found bacteria living on “radioactive water.” Onstott’s writing can be jargon heavy, but he so beautifully conveys his excitement that laypeople and scientists alike will find it a worthwhile read. Photos. (Nov.)