Did Ancient Volcanoes Help Kickstart Life in Earth’s Oceans?

How Earth’s fiery past may have helped life take root in the oceans

Before Earth had oxygen-rich air, before forests, and long before dinosaurs, the planet was a very different place. 

What do I mean by that? As a paleontologist, I’ve always been fascinated by what Earth looked like in the past. We now know that most continents were still submerged, and the atmosphere lacked the breathable oxygen we take for granted today. 

Life existed, but it was microscopic and had to find a way to survive in a largely inhospitable world. But how did life manage?

A new study, led by Dr. Ashley Martin of Northumbria University and published in Nature Communications, takes a fresh look at how life might have gotten a helping hand from an unlikely source: volcanoes. 

The research focuses on fossil stromatolites — layered rock structures built by microbial life — found in 2.75-billion-year-old rocks from Zimbabwe. The team found that volcanic activity played a much bigger role in sustaining early life than previously thought.

But let’s see how they performed this study. 

Hunting for Clues in Fossil Rocks

To figure out how nitrogen was cycled in Earth’s oceans before oxygen became abundant, the researchers analyzed the chemical makeup of fossil stromatolites. Specifically, they measured nitrogen isotopes, which can reveal how nitrogen moved through the environment billions of years ago.

The team examined stromatolites from the Cheshire and Manjeri Formations in the Belingwe greenstone belt, Zimbabwe. These rocks were once part of shallow marine environments where early microbial communities thrived. 

By comparing nitrogen isotope values in shallow-water stromatolites and deeper marine sediments, the researchers were able to reconstruct how nitrogen moved through ancient oceans — and how that movement may have been linked to volcanic activity.

So, what did they find?

Volcanoes, Nitrogen, and Early Life

Well, the results were quite surprising. The team found that nitrogen in deep-water sediments had negative isotope values, while nitrogen in shallow-water stromatolites had unusually high values, reaching up to +42.5‰.

I know, it sounds complicated. What does that mean? Dr. Martin explained it simply:

“Our study reveals high nitrogen isotope values in 2.75-billion-year-old shallow water stromatolites, and lower nitrogen values in deeper marine sediments. This suggests that ammonium, which is nitrogen in its reduced form, accumulated in the deep waters and was brought into shallow waters by upwelling — the movement of deep nutrient-rich water towards the surface of the ocean.”

In other words, Earth’s oceans may have had huge reservoirs of ammonium in their depths, which were stirred up by upwelling currents. 

And what fueled these currents? Likely, the massive volcanic and hydrothermal activity happening at the time. 

This means that volcanoes weren’t just reshaping the planet’s surface — they were also injecting heat and nutrients into the ocean, effectively fertilizing microbial life in shallow waters. The gardeners of early life. 

A Recipe for Biological Innovation?

We know that nitrogen is a fundamental ingredient for life; at the end of the day, all proteins require nitrogen.

Today, nitrogen cycles through the atmosphere, plants, and animals in a well-established pattern. But back then, the nitrogen cycle was still evolving. The fact that volcanic activity may have provided a steady supply of bioavailable nitrogen could have played a major role in early biological evolution.

As Dr. Eva Stüeken of the University of St Andrews put it:

“We have long been puzzled by the unusual nitrogen isotope values in these rocks. Our new findings suggest a strong linkage to hydrothermal nutrient recycling, meaning that early life may in part have been fueled by volcanic activity.”

This idea shifts the way we think about how life sustained itself in ancient oceans. The availability of ammonium in shallow waters would have allowed microbial communities to flourish, setting the stage for bigger biological changes — perhaps even paving the way for the Great Oxidation Event, when oxygen finally began accumulating in the atmosphere.

Why This Matters

Understanding how early life survived and evolved isn’t just something that fills our curiosity needs; it helps piece together the bigger picture of Earth’s history and even provides clues about where life might exist beyond our planet. 

If volcanic activity played a major role in supporting life here, could similar processes be sustaining microbial life on other worlds, like the subsurface oceans of Enceladus or Europa?

Closer to home, this research reminds us of the deep connections between geology and biology. Ultimately, the forces that shape the Earth, including volcanoes, ocean currents, and even the chemistry of ancient rocks, also shape life itself.

Professor Axel Hofmann from the University of Johannesburg summed it up well:

“Volcanism was exceptionally active 2.75-billion-years ago and left a lasting impact on the evolution of life at that time. Rocks in Zimbabwe preserve a remarkable record of this time interval.”

The next time you see steam rising from a volcano or a hot spring bubbling away, consider that billions of years ago, processes like these might have helped jump-start life in the oceans. The story of how life began is still being written, and sometimes, the clues are buried in rocks that have been waiting billions of years to be understood.

Published in Fossils et al. Follow to learn more about Paleontology and Evolution.

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Best,

Sílvia P-M, PhD Climate Ages

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