Life on Earth Could Have Started in Volcanic Pools — but There Are Other Theories to Consider
The billions of microbes that make up the rich menagerie of life on our planet date back to humble beginnings more than 3.5 billion years ago, when our planet was a hot, violent world without oxygen or stable continents. But how and where did life on Earth begin?
For decades, the popular imagination has been dominated by the story of a primordial soup; lightning strikes a warm pond, miraculously propelling dead molecules into living motion. Today, this origin story is called into question. Researchers are increasingly searching for the cradle of life in very different places, from the deepest trenches of the oceans to the boiling edges of volcanoes, and even beyond the Earth itself.
Instead of a constantly wet soup that can break down delicate molecules, some scientists point to terrestrial basins, such as shallow volcanic hot springs, where the chemistry is governed by repeated wet-dry cycles.
Here, chemicals are blasted onto hot rocks, where the water evaporates, and the resulting concentrated slurry brings the reactants together to form larger structures, including protein precursors. When the water returns, these chains return to the pool, ready for another round of building.
A 2024 study in the Proceedings of the National Academy of Sciences demonstrated this exact mechanism, showing that simple wet-dry cycles can spontaneously assemble building blocks into RNA chains several dozen units long. Over millions of repetitions, this natural production facility could have assembled some of the first genetic material.
Learn more: Single-celled organisms laid the foundation for complex life – here’s how
Theory of the origin of life: the battery in the rocks
However, Nick Lane, a biochemist at University College London, thinks this picture may be incomplete. Although surface pools harbor dynamic chemistry, they may have lacked a stable, sustained energy source needed for early life.
Lane and his colleagues instead look for alkaline hydrothermal vents or white smokers deep underwater. Unlike their more acidic counterparts, black smokers that spew superheated liquid, these vents are cooler and chemically gentler. Even more intriguing, they behave a bit like giant cells.
The water inside is basic or alkaline, while the ocean outside is relatively acidic. This pH difference creates a persistent chemical gradient that can drive energetic processes, like how our mitochondria supply our bodies with protons.
“I wouldn’t call it spark at all,” Lane said Discover. “I would talk about the driving forces.”
In this view, the ongoing reaction between bubbling gases like hydrogen and carbon dioxide, aided by metal catalysts in rock such as iron and nickel sulfides, could have produced the building blocks of metabolism long before genes or enzymes existed.
A 2016 study in Astrobiology even mapped how these ventilation systems could power the conversion of CO2 into energy-rich carbon compounds. Before life could have genes, it needed a way to harvest energy to create complex structures.
“The rest of the metabolism,” Lane said, “is spontaneous chemistry from that starting point.”
Origin of Life Theory: Did Life Hitchhike to Earth?
Although marginal, there is a third conjecture that completely avoids the disordered early chemistry called panspermia. This idea suggests that life, or at least its constituent elements, arrived from space, aboard comets or meteorites that settled on a lifeless Earth.
Space is surprisingly rich in organic compounds. In 2023, NASA’s OSIRIS-REx mission returned samples from the asteroid Bennu filled with carbon, water-bearing minerals and phosphates, essential ingredients for life. Even some microbes can be resistant to the conditions of space, tolerating vacuum and radiation for short periods of time by entering a dormant state.
If panspermia occurred, then Earth would not need to invent life from scratch; you just had to catch it, like you catch a cold. However, panspermia does not solve the mystery, it simply pushes it back to an unknown earlier place of birth.
Theory of the origin of life: is the universe full of life?
If life requires a rare combination of wet and dry cycles on a patch of pristine land, then living worlds might be rare. But if a biosphere could spontaneously emerge from hot rocks and simple gases, then the cosmos could be full of life.
“I see a wet, rocky planet or moon inevitably giving rise to alkaline hydrothermal vent systems,” Lane said. Discover. Places like Enceladus and Europa, moons of Saturn and Jupiter with hidden oceans and active geology, suddenly look less like curiosities than potential bio-laboratories.
Scientific enthusiasm is evident with the recent launch of Europa Clipper, the most sophisticated satellite ever sent into Jupiter’s orbit. Scheduled for 2030, it will use ice-penetrating sensors to determine whether the Moon’s icy ocean contains ingredients necessary for life.
Whether we are ultimately the children of volcanic pools or underwater vents, it is becoming increasingly clear that the origin of life may not have been a miraculous spark, but rather a predictable mechanism. By slowly learning how it works, we get closer to understanding our place in the universe.
Learn more: Microbial communities that support human and plant health could be key to life in space
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