Life did not originate in the ocean — scientists find a weak spot in the theory

A new study by geochemist Benjamin Tutolo challenges the hypothesis that life originated in deep-sea hydrothermal vents. The scientist points to a lack of sulfur compounds and inaccuracies in alkalinity estimates at great depths. Small surface water bodies with drying cycles are proposed as an alternative.

A new study by geochemist Benjamin Tutolo from the University of Calgary challenges one of the leading hypotheses about the origin of life on Earth — the theory that life began in deep-sea hydrothermal vents. The scientist identifies two key problems: first, the available sulfur compounds on early Earth may have been significantly less than models assume, and sulfur-containing minerals are considered important for early metabolic processes. Second, alkalinity estimates of hydrothermal fluids may be inaccurate because fluid properties at great depth under high pressure and temperature differ from measurements after samples are brought to the surface. As a result, the necessary chemical gradient may have been much weaker. Tutolo proposes an alternative: small surface water bodies on the young Earth — lakes and ponds that periodically dried up and refilled. Such cycles allowed chemical compounds to concentrate instead of being diluted by the ocean. Under these conditions, molecules necessary for the emergence of RNA, proteins, and lipid structures could form. The work also has implications for the search for extraterrestrial life: if deep-sea vents are less favorable, this could change the assessment of icy worlds with subsurface oceans.