Unraveling the origins of life – Scientists have discovered 'key organic molecules' in ancient vents

Researchers at Newcastle University have made significant progress in understanding the origins of life on Earth by simulating the conditions of ancient hydrothermal vents. This led to the creation of key organic molecules, likely forming the oldest cell membranes. Their findings, which are crucial to understanding the early evolution of life, suggest that life could arise beneath the surfaces of icy moons in our solar system.

Newcastle University scientists, with support from the UK's Natural Environment Research Council, have delved into the mystery of the emergence of life on Earth more than 3.5 billion years ago.

They explored the transformation of inert geological materials into the first living systems. Their experiments involved combining hydrogen, bicarbonate, and iron-rich magnetite under conditions similar to moderate hydrothermal vents. This process resulted in a range of organic molecules, including fatty acids containing up to 18 carbon atoms.

Published in the magazine Earth and Environment CommunicationsTheir findings will likely reveal how some of the key molecules needed to produce life are made of inorganic chemicals, which is essential for understanding a key step in how life formed on Earth billions of years ago. Their results may provide a plausible origin for the organic molecules that make up ancient cell membranes, which may have been selectively selected by early biochemical processes on primitive Earth.

Fatty acids in the early stages of life

Fatty acids are long organic molecules that contain regions that attract and repel water that would spontaneously form cell-like compartments in water naturally, and it is these types of molecules that could have made the first cell membranes. However, despite their importance, the source of these fatty acids in the early stages of life has not been certain. One idea is that they may have formed in hydrothermal vents where hot water and hydrogen-rich fluids coming from underwater vents mix with seawater containing carbon dioxide.₂.

The group replicated important aspects of the chemical environment found in Earth's early oceans and the mixing of hot alkaline water from certain types of hydrothermal vents in their laboratory. They found that when hot hydrogen-rich liquids were mixed with carbon dioxide-rich water in the presence of iron-based minerals that were present on early Earth, the types of molecules needed to form primitive cell membranes were created.

Lead author, Dr Graham Purvis, conducted the study at Newcastle University and is currently a postdoctoral research associate at Durham University.

He said: “Cellular compartments are the central element in the origin of life, and are essential for isolating internal chemistry from the external environment. These compartments have been instrumental in promoting life-sustaining reactions by concentrating chemicals and facilitating energy production, and likely serve as a cornerstone.” In the first moments of life.

The results suggest that the affinity of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the primitive membranes of early cells at the beginning of life. This process may have generated a variety of membrane types, some of which likely served as the cradle of life when life first began. Furthermore, this transformational process may have contributed to the formation of specific acids found in the elemental composition of meteorites.

Lead researcher Dr John Tilling, Reader in Biogeochemistry in the School of Natural Environmental Sciences, added:

“We believe this research may provide the first step in how life arose on our planet. Research in our laboratory is now continuing to determine the second key step; how these organic molecules that were initially 'stuck' to metal surfaces could break free to form cell-like chambers surrounded by a spherical membrane.” The first possible “protocells” that formed the first cellular life.

Interestingly, the researchers also point out that membrane-forming reactions still occur in the oceans beneath the surfaces of the icy moons in our solar system today. This raises the possibility of alternative life origins on these distant worlds.

Reference: “Generation of Long-Chain Fatty Acids by Hydrogen Bicarbonate Reduction in Ancient Alkaline Hydrothermal Vents” by Graham Purvis, Lydia Schiller, Archie Crosky, Jupiter Vincent, Corinne Wells, Jake Shreve, Sijo Xavier and John Tilling, January 10, 2024, Earth and Environment Communications.
doi: 10.1038/s43247-023-01196-4

The study was funded by the Natural Environment Research Council.