A new study by scientists at Newcastle University sheds light on how life may have emerged from inorganic chemicals on Earth over 3.5 billion years ago. The researchers simulated the environment of ancient underwater hot springs and discovered that they could produce organic molecules, such as fatty acids, that are essential for the formation of cell membranes. The study, published in Nature Communications Earth & Environment, has implications for understanding the origins of life on our planet and beyond.
How hot springs could have created life
The origin of life is one of the most fascinating and challenging questions in science. It requires unraveling the complex steps that led to the transition from simple molecules to living systems. One of the key steps is how inorganic chemicals could have generated organic molecules, such as amino acids, nucleotides, and fatty acids, that are the building blocks of life.
Fatty acids are particularly important because they can form cell-like structures in water, called vesicles, that have both hydrophilic (water-loving) and hydrophobic (water-repelling) regions. These vesicles could have acted as the first cell membranes, isolating internal chemistry from the external environment and facilitating reactions and energy production.
However, the origin of fatty acids in the early stages of life has been a matter of debate. Some hypotheses suggest that they were produced by hydrothermal vents, where hot, hydrogen-rich fluids interacted with carbon dioxide-rich seawater. However, these vents are often too hot and acidic for organic molecules to survive.
The researchers at Newcastle University decided to test a different scenario: mild hydrothermal vents that were more alkaline and less extreme. They mixed hydrogen, bicarbonate, and iron-rich magnetite under conditions mimicking these vents. To simulate the ancient hot springs, they used a high-pressure reactor that allowed them to control the temperature, pressure, and chemical composition of the fluids. They also added magnetite nanoparticles to act as catalysts for the formation of organic molecules. They found that they could produce a range of organic molecules, including fatty acids with up to 18 carbon atoms.
Implications for the origins of life on Earth and beyond
The results of the study suggest that ancient hot springs could have been a potential source of organic molecules needed for the earliest cell membranes. The researchers propose that the interaction of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the formation of these molecules on the mineral surfaces. These molecules could have then detached from the minerals and formed vesicles in water, possibly serving as the cradle of life.
The study also has implications for the search for extraterrestrial life. The researchers point out that similar processes could be occurring in the subsurface oceans of icy moons, such as Europa and Enceladus, where hydrothermal activity has been detected. These moons could harbor organic molecules that could support life or indicate its presence.
The study is a significant step towards understanding how life originated on Earth and possibly elsewhere. The researchers plan to continue their experiments to determine how these organic molecules could have formed vesicles and protocells, the precursors of cellular life.