The origin of life on Earth may not have occurred where many scientists assumed. New research, led by geochemist Benjamin Tutolo from the University of Calgary, considers it 'highly unlikely' that deep-sea hydrothermal vents were the cradle of life.
The study, published in the scientific journal PNAS, challenges the chemical premises that have been used for decades in this hypothesis. According to Tutolo, the possibility of life arising in lakes and puddles that evaporated on the early surface of Earth is more consistent with current data.
Hydrothermal vents are extreme environments at the bottom of the oceans where hot fluids circulate through rocks. The idea of life originating in such places gained support because these conditions seemed to provide the necessary components to initiate important chemical reactions.
One of the key arguments was the difference in acidity between the primitive ocean and the alkaline fluids of the vents. This contrast could function as a kind of chemical battery, powering reactions leading to the first components of life.
However, according to Tutolo, modern knowledge of these environments does not support some of these assumptions. The researcher told ScienceAlert: 'The hypotheses about hydrothermal vents are so ingrained in our culture that many of us have stopped questioning them.'
Older hydrothermal vents were likely not as alkaline or sulfur-rich as previously thought. This directly affects models that assign an important role to sulfide minerals in the first metabolic processes.
There is also another issue. High levels of alkalinity were observed in fluids extracted from vents and analyzed after reaching the surface. Nevertheless, at the temperatures and pressures existing at the ocean floor, these fluids would be significantly less alkaline.
While this may seem like a technical point, it has an important implication: the strong proton gradient necessary for some versions of the hypothesis may never have existed in that form.
Tutolo emphasized: 'These problems are so fundamental that the hypotheses about hydrothermal vents for the origin of life must return to the drawing board.'