It is not a chef who prepares it, nor a restaurant that serves it. The broth brewing in the laboratory of the Donostia International Physics Center (DIPC) is part of PROTOS, an ambitious scientific project funded with 10 million euros by the European Research Council through an ERC Synergy Grant and led by the Ikerbasque Research Professor Juan Manuel García-Ruiz at the DIPC. PROTOS aims to create primitive worlds, or PROTO-worlds, inside glass flasks to study, among other things, the role of silica in that "primordial soup" that gave rise to life on Earth.
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The idea of recreating the conditions of early Earth in a flask is not new; it is based on the famous experiment conducted by scientist Stanley Miller on the same year Juan Manuel García-Ruiz was born. "It is one of the most elegant and interesting experiments in the history of science," says García-Ruiz, referring to this experiment which, like PROTOS, combines water, gases, and electrical discharges inside a glass reactor.
García-Ruiz was a pioneer in 2021 when he decided to modify a key aspect of Miller’s experiment by replacing the glass reactor with one made of Teflon, an inert material. The result was revealing: neither amino acids nor nucleobases—the fundamental building blocks of life—appeared, unlike in previous experiments. “It was an iconic experiment that no one dared to question. It took us years to explain that we weren’t challenging Miller’s experiment, but rather incorporating the silica from the glass as a key variable in the formation process of amino acids,” García-Ruiz explains.
According to García-Ruiz, the atmosphere and water were not the only catalysts of life in the primordial soup. The rocks in which this broth was "cooked" also played a crucial role, particularly because they contained silica and silicates.
"I have always believed that silica is fundamental in the synthesis of prebiotic compounds, and with PROTOS, we have gone even further. Our results show that silica also induces the formation of biomorphic structures, or protocells—compartments essential for enabling more complex reactions and, eventually, life. We believe these hollow vesicles were always present, even in Miller’s experiment, but no one had looked for them because they were thought to be a later phenomenon," explains Professor García-Ruiz.
With García-Ruiz joining the DIPC as an Ikerbasque Research Professor, both institutions now host the ERC Synergy Grant PROTOS, opening a new line of research at the DIPC. "With PROTOS, the DIPC will develop a cutting-edge research program on the chemical and physical processes that led to the emergence of the first living organisms. The PROTOS project is truly fascinating, and it is a privilege to carry it out at our center," states Ricardo Diez Muiño, director of the DIPC.
For Ikerbasque, in the words of its scientific director Fernando Cossio, "The frontier of knowledge draws us in with increasing force, proportional to the ambition of the questions we pose and the projects that seek to answer them. Each time a doubt is resolved, new questions arise—more mysteries that encourage us to keep exploring. The significance of projects like this confirms that in the Basque Country, we are in a position to support pioneering research, providing the necessary conditions for scientists of Juan Manuel García-Ruiz’s caliber to trust Ikerbasque and the DIPC to develop both their scientific and personal projects."
For Professor García-Ruiz, joining the DIPC has allowed him to retain his position as an ad honorem professor at the Spanish National Research Council (CSIC) in the Andalusian Institute of Earth Sciences in Granada, build his own Laboratory of Mineral Self-Organization and Origin of Life from scratch, and continue pursuing another of his passions—scientific outreach. "The reception at the DIPC has been excellent. We have the support of the Basque Government through Ikerbasque, we are building a state-of-the-art laboratory to advance our research, and I have been able to develop outreach projects alongside the DIPC. I am delighted," says García-Ruiz.
First Results of PROTOS
PROTOS is an international collaboration led by Ikerbasque Professor Juan Manuel García-Ruiz, with the participation of the DIPC as project coordinator, the University of Bremen, the Naturalis Biodiversity Center in Leiden, the Leibniz University Hannover, the Geo-Ocean laboratory of the CNRS, the Andalusian Institute of Earth Sciences (IACT-CSIC), and the Génie Chimique laboratory at the National Polytechnic Institute of Toulouse.
The first results of PROTOS were recently published in the journal Proceedings of the National Academy of Science (PNAS). In this study, García-Ruiz and his team provide new evidence suggesting that silica induced the formation of biomorphic structures, which García-Ruiz defines as "protocells."
The images of these protocells spread around the world. According to García-Ruiz, the presence of these hollow vesicles in the PROTOS flasks suggests that the conditions for life existed on Earth much earlier than previously thought—during the Hadean eon, which began with the formation of our planet 4.6 billion years ago and ended 4 billion years ago.
"The results of PROTOS indicate that all the basic ingredients for life were there from the very beginning. This implies that life is the result of a slow, clumsy, yet persistent chemical evolution spanning millions of years. There is no divine spark, no intelligent design—just a collection of truncated trees alongside the tree of life."
As PROTOS experiments progress, García-Ruiz cautions: "The boundary between the living and the non-living is becoming increasingly blurred. We are far from understanding the full sequence that led from simple molecules to living organisms, but we continue to ‘cook’ to see what happens."
A brown layer can be observed on the walls of the flasks, a result of electrical discharges and ultraviolet radiation, within which García-Ruiz and his team have already identified up to 17 types of amino acids and the five nucleobases that make up DNA. Additionally, small dark particles can be seen floating on the surface of the broth. "Those floating particles are the hollow vesicles we call protocells. They are tiny compartments that allow prebiotic compounds to react with one another and evolve toward greater complexity," explains García-Ruiz. On the walls of these vesicles, his team has found polymers of hydrogen cyanide— a simple molecule composed of a hydrogen, a carbon, and a nitrogen atom. "Several studies suggest that from these polymers, everything can be created—including life," García-Ruiz asserts.
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