Simulating the chemical environment before the emergence of life

New research reveals how the first cells on Earth formed

Scientists at the Scripps Research Institute in the United States have discovered a plausible pathway that could explain how protocells formed and achieved their multiple functions. The study, published online in the journal Chem on February 29, shows that a chemical process called phosphorylation (adding phosphate groups to molecules) occurred much earlier than previously thought. This led to structurally more complex double-chain protocells that could divide with multiple functions, laying the foundation for life.

About 4 billion years ago, Earth was nurturing conditions suitable for life. But there are too many mysteries in this. Scientists believe that protocells were formed from fatty acids, but it has remained unclear how protocells transitioned from single chains to double chains of phosphate, which made them more stable and capable of chemical reactions.

The team this time hoped to mimic the environment that existed before life emerged. They first identified three possible mixtures of chemicals that could produce vesicles, that is, lipid spherical structures similar to protocells. The chemicals used included fatty acids and glycerol. Next, they observed the reactions of these mixtures and added additional chemicals to create new mixtures. These solutions were cooled and heated overnight, and then shaken to promote chemical reactions.

The researchers used fluorescent dyes to examine the mixtures and determine whether they formed vesicles. They varied the pH and the ratios of components to better understand how these factors affect vesicle formation, and also analyzed the effects of metal ions and temperature on vesicle stability.

It turned out that fatty acids and glycerol may have undergone phosphorylation to produce more stable double-chain structures. In particular, glycerol-derived fatty acid esters may have caused vesicles to have different tolerances to metal ions, temperature, and pH, which is a key step in evolutionary diversification.

The researchers pointed out that this new discovery helps people better understand the chemical environment of the early Earth, so as to reveal the origin of life and how life evolved on the early Earth.

[Editor-in-Chief's Commentary]

Scientists studying the origin of life already know that protocells were the precursors of cells during the emergence of life. But how did simple protocells appear and become diversified, eventually forming life on Earth? And were the types of chemistry found on the early Earth similar to the needs of life today? Now they have found that phosphate was incorporated into cell-like structures earlier than previously thought, which laid the foundation for the emergence of life. It is precisely by revealing how protocells formed that scientists have gained a better understanding of the "truth" of what happened in early evolution.