How did life start? It’s a question that has intrigued humans ever since we became conscious of ourselves and our place in the world. Now, researchers from Newcastle University in the UK may have an answer. By investigating the conditions that may have allowed living systems to emerge from inert geological materials 3.5 billion years ago, the team were able to produce organic molecules that may have been the stuff of life.
When they mixed hydrogen, bicarbonate, and iron-rich magnetite under conditions similar to those of mild hydrothermal vents, the researchers were able to create a spectrum of molecules, including fatty acids that were up to 18 carbon atoms in length.
This result potentially reveals how key molecules that underpin life can be made from inorganic chemicals. This has big implications for our understanding of how life may have formed on the Earth billions of years ago. In particular, this study offers a plausible genesis for organic molecules that form cell membranes that were possibly selectively chosen by early biochemical processes on the ancient Earth.
Primordial fatty acids
Fatty acids have some special properties. They are long organic molecules that have regions that can attract and repel water, which allows them to naturally form cell-like compartments in water. It is possible these molecules formed the first cell membranes.
However, prior to this research, it was not clear where these fatty acids originally came from. It had been suggested that they may have formed in hydrothermal vents where hot water, mixed with hydrogen-rich fluids produced by underwater vents, combined with seawater containing carbon dioxide.
In essence, the researchers created their own laboratory hot vent to replicate this environment under controlled conditions.
They found that, when they mixed hot hydrogen-rich fluids with carbon dioxide-rich water in the presence of iron-based minerals, which were present on the Earth, it created these fatty acids.
“Central to life's inception are cellular compartments, crucial for isolating internal chemistry from the external environment”, lead author Dr Graham Purvis said in a statement.
“These compartments were instrumental in fostering life-sustaining reactions by concentrating chemicals and facilitating energy production, potentially serving as the cornerstone of life's earliest moments.”
Purvis added, “The results suggest that the convergence of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the rudimentary membranes of early cells at the very beginning of life. This process might have engendered a diversity of membrane types, some potentially serving as life's cradle when life first started. Moreover, this transformative process might have contributed to the genesis of specific acids found in the elemental composition of meteorites.”
The team believe this work represents an important step in understanding how life originated on the planet.
“Research in our laboratory now continues on determining the second key step; how these organic molecules which are initially ‘stuck’ to the mineral surfaces can lift off to form spherical membrane-bounded cell-like compartments; the first potential ‘protocells’ that went on to form the first cellular life,” principal investigator Dr Jon Telling explained.
Interestingly, these results could have implications that span beyond our own planet. It is possible similar membrane-creating reactions are currently taking place in the oceans under the icy moons in our Solar System. Perhaps alternative life is emerging as we speak on other worlds.
The study is published in Communications Earth & Environment.