Protocells may have formed in the proximity of prebiotic compounds

The origins of life on Earth remain one of the most fascinating and profound questions in science. A new research ¹ sheds light on this mystery by exploring how the building blocks of life could have formed under early Earth conditions. In this study, we focused on understanding how simple chemicals might have come together to create more complex structures, including those resembling the precursors to living cells.

Life as we know it is built upon complex molecules like proteins, nucleic acids (DNA and RNA), and lipids. However, billions of years ago, the Earth was a vastly different place, with no living organisms to produce these molecules. Understanding how these molecules first formed—and how they came together to create the structures necessary for life—can provide crucial insights not only into our own history but also into the possibility of life on other planets.

One of the key challenges in studying the origins of life is recreating conditions that mimic those of the early Earth. While it’s impossible to perfectly replicate such a distant and dynamic environment, scientists have developed experimental models that simulate plausible scenarios. These models often include elements like water, volcanic activity, lightning, and simple gases, all of which are believed to have been abundant on primordial Earth.

Recreating early Earth conditions

In theexperiment, we designed a setup to mimic the environment that might have existed on early Earth. We combined water, silica (a common mineral found in sand and rocks), and electrical discharges in a controlled laboratory setting. The electrical discharges were meant to simulate lightning, a source of energy that was likely frequent in Earth’s turbulent early atmosphere.

We introduced hydrogen cyanide (HCN) into this system. While HCN is a simple and toxic molecule, it is thought to have played a critical role in prebiotic chemistry. Under the right conditions, HCN can react with other molecules to form a variety of organic compounds, including those that are precursors to biomolecules like amino acids and nucleotides.

What we observed was remarkable. The interaction of these components led to the formation of solid organic films composed of hydrogen cyanide polymers. These polymers are long chains of molecules that are chemically similar to some of the components found in modern biological systems.

Formation of protocell-like structures

One of the most exciting aspects of the work was the discovery that these organic films spontaneously organized into structures resembling primitive cells, or “protocells.” Protocells are considered a critical step in the origin of life because they provide a contained environment where chemical reactions can occur more efficiently, potentially leading to the emergence of self-replicating systems.

The protocells we observed varied in size, ranging from nanometers to micrometers. These sizes are comparable to the size of modern microbial cells. They formed at the interface between gas bubbles and water, suggesting that such interfaces might have played an important role in the chemistry of early Earth.

The formation of protocells in the experiment did not require the presence of complex molecules or biological processes. Instead, they appeared to form through purely physical and chemical interactions. This finding supports the idea that protocell-like structures could have arisen naturally under the right environmental conditions, even before the advent of life.

Simultaneously and in close proximity

The study results suggest that two critical components for the emergence of life—protocells and complex organic molecules—could have formed simultaneously and in close proximity to each other. This scenario would have created a favourable environment for further chemical evolution, potentially leading to the development of the first living organisms.

Previous research has often focused on either the formation of organic molecules or the assembly of protocell-like structures. The new work bridges this gap by showing that these processes could have been interconnected. This insight is significant because it suggests that the transition from chemistry to biology might have been more seamless than previously thought.

The search for life beyond Earth

The conditions we recreated in the laboratory are not unique to early Earth. Similar conditions could exist on other planets or moons with volcanic activity, liquid water, and a source of energy like lightning or radiation. For example, Jupiter’s moon Europa and Saturn’s moon Enceladus both have subsurface oceans and are considered prime candidates in the search for extraterrestrial life.

These findings provide a framework for understanding how life might arise in such environments. By identifying the key chemical and physical conditions required for the formation of protocells, we can better target our search for life beyond Earth.

Looking ahead

While the study represents a significant step forward, it is just one piece of the puzzle. There is still much to learn about how protocells could have evolved into true living cells capable of growth, replication, and metabolism. Future research will focus on exploring how simple molecules could have developed the ability to store and transfer information (as DNA and RNA do in modern organisms) and how early metabolic pathways might have arisen.

Additionally, we plan to investigate how varying environmental conditions, such as changes in temperature, pH, and chemical composition, might affect the formation and stability of protocells. Understanding these factors will provide a more comprehensive picture of the diverse pathways through which life could have originated.

This research offers exciting new insights into one of science’s greatest mysteries: how life began on Earth. By showing that protocells and essential organic compounds can form simultaneously under early Earth-like conditions, we have taken a step closer to understanding the processes that led to the emergence of life. These findings not only illuminate our own origins but also guide us in the search for life elsewhere in the universe.

The journey to uncover life’s origins is far from over, but studies like ours bring us ever closer to answering the fundamental question: Where do we come from?

Author: César Tomé López is a science writer and the editor of Mapping Ignorance

Disclaimer: Parts of this article may have been copied verbatim or almost verbatim from the referenced research paper/s.