Over 4.5 billion years ago, the Earth was a superheated sphere of molten rock, radiating heat to space at over 2000 K. A billion years later, it had global oceans, teeming with microorganisms. In that time, the Earth underwent massive geological changes, somehow serendipitously creating conditions right enough to lead to the spontaneous emergence of cellular life. It has been suggested that these primitive forms of life may have originated around hydrothermal vents at the bottom of the ancient ocean, and that similar environments could host extraterrestrial life elsewhere in the solar system. Until recently, our typical picture of such hydrothermal vent systems was that of the gargantuan black smoker chimneys driven by mid-ocean ridge volcanism. Here, hyperthermophilic chemolithotrophic archaea brave the extremely hot, acidic, sulfurous waters in order to oxidize inorganic compounds released in the vent fluids. However, with the year 2000 discovery of the Lost City Hydrothermal Field and its cooler, alkaline “white smokers” (Figure 1), our view of sea-floor hydrothermal environments has begun to change. Many scientists are now turning their attention to these off-axis (some kilometers from the volcanic mid-ocean ridge) hydrothermal environments, and to their geological driving force, a process called serpentinization. Might this be the energy source for the first life on Earth and, who knows, for life elsewhere?
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