The original version of this story appeared in Quanta Magazine.
Water is the most fundamental need for all life on Earth. Not every organism needs oxygen, and many make their own food. But for all creatures, from deep-sea microbes and slime molds to trees and humans, water is nonnegotiable. “The first act of life was the capture of water within a cell membrane,” a pair of neurobiologists wrote in a recent review. Ever since, cells have had to stay wet enough to stay alive.
Water is the medium in which all chemical reactions in an organism take place, and those reactions are finely tuned to a narrow range of ratios between