For 15 years, biochemist Sébastien Fontaine has been on a quest to understand soil. At the French National Institute for Agriculture, Food, and Environment, he and his team focused on soil’s hidden carbon emissions. They wanted to see how much carbon could be released from soil that had no life. To do this, they sealed dirt in jars and used gamma radiation to eliminate any organisms inside. They expected that the carbon dioxide emissions would stop. Surprisingly, they did not.
Despite the soil looking lifeless, it continued to emit carbon dioxide for years. This led Fontaine and his team to investigate further. They discovered that even in sterile soil, there were signs of metabolic processes—the very actions that fuel life. Their findings, reported in 2025 in Science Advances, suggest that processes typically associated with living cells might also occur in nonliving materials. Fontaine speculates that some of these reactions might even predate life on Earth.
Joseph Moran, an organic chemist at the University of Ottawa, commented, “What they’re finding is that the chemistry of life is not exclusive to life. It’s the chemistry of geology.” This insight sparks questions about our understanding of life and its origins.
Fontaine’s initial goal was to measure carbon in dead soil. He and his team used a sterile syringe to collect air samples, which showed a steady carbon emission, even after radiation had killed off microbes. When they introduced enzymes from yeast, the carbon emissions jumped, indicating that some biochemical reactions were still occurring even without living cells.
Initially, many in the scientific community dismissed Fontaine’s work as an experimental error. They suggested he move on. But he couldn’t shake the feeling that something significant was happening. Over the years, he faced skepticism, but he remained persistent, refining his methods and exploring every angle.
In 2018, with the arrival of Clémentin Bouquet, the team began to delve deeper into the mechanisms behind their observations. They studied two types of soil—irradiated normal soil and glucose-supplemented soil. For over 1,000 days, they took regular samples of the carbon dioxide emissions. The findings were striking: both types of soil continued to emit carbon, with the glucose-enhanced samples producing even more.
Now, Fontaine proposes that soil can perform actions similar to cellular metabolism, even lacking the internal structures and enzymes of living cells. This challenges the long-held belief that the Krebs cycle, a crucial component of cellular metabolism, only happens within living organisms.
Remarkably, he created a fuel cell to measure electron flow through irradiated soil. This electricity indicated metabolic-like processes ongoing in what was presumed to be lifeless dirt.
Joshua Schimel, a soil ecologist, found the results aligned with emerging theories about life’s origins. He noted, “Glucose naturally, in the process of being oxidized, is going to form some of these Krebs-cycle intermediates.”
Recent studies suggest that metals like iron and zinc could facilitate biochemical reactions even before life evolved. This challenges traditional views of life’s beginnings. As Markus Ralser, a biochemist, points out, “If [metabolism] would be very hard to do, then the planet would not be full of life now.” Ralser believes that metabolic reactions might even be more common in nature than we think.
Bouquet, now exploring the prebiotic origins of other biochemical processes, adds, “I find it particularly interesting to imagine the survival of processes that may predate life itself right there under our feet.”
Fontaine’s research invites us to rethink the boundaries of life, suggesting that we may have much to learn about the dynamics of our planet’s soils. The dialogue among researchers continues to evolve, highlighting the intricate relationships between geology and life—and how they might inform our understanding of life’s origins.
