Walk around the American Museum of Natural History and you’ll see some odd biological specimens. Green fuzz, fluorescent blobs, muscular tubes and swarms of bipeds paying good money to stare at rocks. But by the standards of “Weird Life,” by David Toomey, those sights are positively pedestrian.
In his exploration of biodiversity, real and hypothetical, Toomey starts close to home, on Earth. For years scientists have documented extremophiles — microorganisms fond of extremes in temperature, pressure or acidity. (Just a few weeks ago, researchers discovered bacteria in an Antarctic lake under half a mile of ice.) Some bacteria survive in rock, others in clouds. But extremophiles are just Toomey clearing his throat. All the life we know of evolved from the same primordial ancestor; by “weird,” he means organisms with an independent origin and a family tree all their own. His book considers whether and where and how such entities might exist.
(W. W. Norton) - ’Weird Life: The Search for Life That Is Very, Very Different from Our Own’ by David Toomey
Depending on what materials were available at inception, life as we don’t know it might rely on ammonia instead of water, or arsenic (poison to us) instead of phosphorous (possibly poisonous to them). “If life had taken a different course,” Toomey writes, “then we — or weird-life versions of us — might be suffering through summer stock productions of ‘Phosphorus and Old Lace.’ ” Raising the specter of a shadow biosphere here on Earth, he attenuates the ominousness of such a prospect by likening it to “the realm of fairies and elves just beyond the hedgerow.”
Early on, Toomey pauses to clarify exactly what we’re hunting for. A brain trust organized by the National Research Council decided after five years that defining life was futile, but they noted that the best definitions were along the lines of “chemical systems capable of Darwinian evolution.” Biologists generally agree that life requires an energy source, a semipermeable membrane and macromolecules, but this is a list of features, not a fundamental theory. Finding life not like our own, however, might help us discover universal biological laws, similar to physical laws. Knowing how common it is for life to evolve might also rejigger our envisioned place in the cosmos. Those might be reasons enough to search for it.
So off we go, knocking on neighbors’ doors. Several missions to Mars have poked around for evidence of life-supporting conditions. Scientists have also looked to Jupiter’s moon Europa, where microbes could be hanging out near hydrothermal vents in an ocean under its thick icy crust, and to Saturn’s moon Titan, where microbes might breathe hydrogen and bathe in liquid methane, eschewing the Earthling-preferred oxygen and water. And once upon a time Carl Sagan and a co-author proposed, in a scientific article, an ecology in Jupiter’s atmosphere based on thin-skinned, hydrogen-filled “floaters” the size of cities. Farther out, NASA’s Kepler space telescope is finding hundreds of new planets every year, out of the hundreds of billions that might exist in our galaxy.