Silica and the spark of life: new research reveals how protocells formed on early earth

A new study published in the Proceedings of the National Academy of Sciences (PNAS) shows that protocells and prebiotic compounds may have formed together under early Earth-like conditions. Researchers from the Donostia International Physics Center (DIPC), the Spanish National Research Council (CSIC), and the universities of Valladolid and Cádiz built on the famous 1953 Miller-Urey experiment, which showed that essential organic molecules could form in a simple environment with a reducing atmosphere, alkaline water, and electrical sparks.

The research, which is part of the ERC-Synergy Grant project “PROTOS: The role of silica in the dawn of life on our planet” (DOI 10.3030/101118811), finds that silica appears to be a key component in the experimental setup, playing a crucial role in the protocell formation. In reactors containing silica-rich surfaces, water-gas mixtures, and an electrical discharge which simulates lightning, the initially clear water turns into a yellow-brown “soup” over the course of two weeks, with a brownish insoluble organic film forming on reactor walls and the water-gas interface. Analysis of these films shows the presence of micrometer-scale hollow vesicles composed of hydrogen cyanide (HCN) polymers, structurally resembling biological organism. The study suggests that these biomorphic protocells form through a process of bubbling and air-water interfacial precipitation.

These findings challenge the traditional notion that the synthesis of life’s building blocks and the formation of cellular compartments were two events separated in time. They suggest that both processes may have occurred concurrently on early Earth. The results align with emerging models of the Hadean Eon of the ancient Earth, which featured a reducing atmosphere, thunderstorms, high ionic radiation, silicate-rich rock surfaces/water bodies, as well as the presence of liquid water itself. The iterative synthesis of increasingly complex prebiotic compounds within biomorphic microreactors introduces a new geochemical framework for the origin of life.

Beyond Earth’s history, the research has significant astrobiological implications. The discovery of biomolecules such as amino acids and nucleobases alongside life-like organic and hollow structures in Martian rocks or meteorites does not necessarily indicate extra-terrestrial life anymore. Instead, it suggests that similar organic “protoworlds” may exist widely across the universe on any Earth-like planets, moons, and other bodies, potentially evolving into different forms of life.

By providing a novel perspective on prebiotic chemistry and compartmentalization, this study opens new avenues for exploring both the origins of life on Earth and the search for life beyond our planet.

Concomitant formation of protocells and prebiotic compounds under a plausible early Earth atmosphere

Jenewein, C., Maíz-Sicilia, A., Rull, F., González-Souto, L., García-Ruiz, J.M. (2024). PNAS, 122(2). https://doi.org/10.1073/pnas.2413816122