Life may have emerged a billion years earlier than we thought

Earth holds memories far older than humans. These memories rest inside ancient stones shaped by heat, pressure, and time. Many early signs of life vanished as these rocks changed deep within the crust.

Yet scientists continue to search for faint signals that survived. A new study reveals chemical traces of biology in rocks older than 3.3 billion years.

The research suggests that oxygen-producing photosynthesis began far earlier than expected.

The study paired modern chemistry with artificial intelligence. The goal was simple: to read chemical messages left behind by early organisms.

The messages exist as small molecular fragments. These fragments persist even when original cells or biomolecules have long disappeared.

Signs of early life in rocks

The team trained machine learning systems to study the chemical profiles of many organic materials. The system learned how life shapes molecular patterns in a way that non biological processes do not.

Once trained, the system examined ancient rocks and detected signals that point to life, even in samples older than three billion years.

The study shows that life left a more durable chemical trail than once thought. These trails appear as faint patterns inside highly altered rocks.

Many earlier models could not read these traces. The new method opens a wider window into early Earth, building on a growing body of work that uses chemical data and artificial intelligence.

Previous research showed that organic matter formed by life carries different molecular patterns than material formed through non biological chemistry. The new study extends that idea with a larger range of samples and a more powerful model.

Fossils with meaning

Michigan State University scientist Katie Maloney joined the project. She studies early complex life and ancient ecosystems.

Maloney contributed rare seaweed fossils from Canada that date back one billion years. These fossils represent some of the earliest known seaweeds at a time when most life stayed microscopic.

“Ancient rocks are full of interesting puzzles that tell us the story of life on Earth, but a few of the pieces are always missing,” Maloney said. “Pairing chemical analysis and machine learning has revealed biological clues about ancient life that were previously invisible.”

Her samples helped confirm that the method works on very old fossils as well as younger ones. These fossils hold organic fragments that still reflect the nature of the organisms that once lived.

A clear biological pattern

The new study was focused on detailed analyses of more than 400 samples. These samples included modern plants, modern animals, fossil microbes, fossil plants, meteorites, ancient sedimentary rocks, and synthetic materials.

The researchers examined each sample using pyrolysis gas chromatography with mass spectrometry. This method breaks organic matter into many small fragments for study.

Artificial intelligence then examined these fragments. The models separated biological and non biological material with strong accuracy.

The models also identified traits linked to metabolism. These traits included signals from photosynthetic organisms as well as non photosynthetic organisms.

The results confirm that even broken and degraded molecular remains still hold a clear biological pattern. Heat, pressure, and chemical changes often destroy full biomolecules. Yet the pattern formed by many fragments still reveals the presence of life.

Echoes of life in ancient rocks

The team found that several samples older than three billion years carry strong signals of biological origin.

Some samples resemble microbial material. Others show clear links to early forms of photosynthetic life. This discovery pushes back the evidence for oxygen-producing photosynthesis by nearly a billion years.

The method also distinguishes biological organic matter from meteorite derived organic matter. This is important because some ancient rocks contain both types. The ability to separate the two offers strong potential for future space missions.

Researchers need to know if a rock from Mars or another world once held living organisms or only non biological carbon from space.

“Ancient life leaves more than fossils; it leaves chemical echoes,” said Dr. Robert Hazen. “Using machine learning, we can now reliably interpret these echoes for the first time.”

Patterns across eras

The combined findings show a pattern through Earth history. Younger rocks contain clear biological signatures. Older rocks contain weaker but still recognizable biological signals.

This decline likely reflects increasing molecular damage with age. It may also reflect the presence of some non biological organic matter in the oldest samples.

Yet the important point remains. Many Paleoarchean samples still carry patterns that point to life.

These results align with earlier work that used morphology and isotopes to study early life. The new method adds chemical strength to those earlier lines of evidence.

Together, they show that early Earth hosted a rich microbial world long before complex organisms appeared.

The search for alien life

“This innovative technique helps us to read the deep time fossil record in a new way,” said Maloney. “This could help guide the search for life on other planets.”

The method may soon combine more types of data. Scientists plan to add isotope ratios, Raman spectra, infrared spectra, and morphological data.

Such additions may reveal even deeper details about early life. They may also help detect non-oxygen-based photosynthesis and other ancient metabolic processes.

The long term goal is clear. Researchers want to understand how life began, how it changed through deep time, and how to detect it on distant worlds.

The new results show that even Earth’s oldest rocks still preserve chemical memories of early life – and those memories are now speaking more clearly than ever.

The study is published in the journal Proceedings of the National Academy of Sciences.

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