Life, as we knew it only a few decades ago, needed sunlight and warmth. No one imagined that anything could survive in extreme environments -- in intolerable places such as high-pressure, high-temperature deep-sea vents or under Antarctic ice sheets.
That was before the discovery, in 1977, of extremophiles, a special class of organism that lives in extreme conditions. Scientists thought that being an extremophile was like being an astronaut: To qualify, you've got to have the right stuff. But now scientists have shown that even common, ordinary bacteria, such as Escherichia coli (which is present in the human stomach), can survive under extreme conditions. In this study, that meant immense gigapascal pressures, 16 thousand times that of atmospheric pressure at sea level.
That life can exist under extreme conditions encourages those looking for extraterrestrial life, and might help us recognize the value of life on our own planet.