14/12/2025
Scientists just found 3.3‑billion‑year‑old chemical “echoes” of ancient life.
Fossilized carbon preserved in 3.33‑billion‑year‑old rock from South Africa’s Josefsdal Chert has yielded the earliest and most secure chemical evidence of life yet detected on Earth. Using machine learning on data from pyrolysis‑gas chromatography‑mass spectrometry (Py‑GC‑MS), researchers identified subtle, characteristic patterns of organic fragments that distinguish biologically produced carbon from non‑biological material. Trained on 406 samples spanning modern organisms, young fossils, stromatolites, and highly altered ancient carbon, the algorithm achieved over 90 percent accuracy in flagging biotic signatures, even when visible fossils were absent or degradation was extreme. This shows that ancient life can leave behind enduring “chemical echoes” that persist long after conventional fossil structures have been erased.
The study also pushed back the earliest firm evidence of photosynthesis, finding biotic signals in 2.52‑ and 2.3‑billion‑year‑old rocks from South Africa and Canada, respectively, extending the documented timeline of this metabolism by more than 800 million years. While still unable to confirm life in even older samples—such as 3.7‑billion‑year‑old Greenland carbon and 3.5‑billion‑year‑old Australian stromatolites—the work demonstrates that life had clearly emerged and spread across Earth by 3.33 billion years ago and that its biochemical imprint can be decoded with modern AI tools. By pairing advanced chemical analysis with machine learning, scientists have opened a new way to read “molecular ghosts” in Earth’s oldest rocks, with implications not just for early life on our planet, but for detecting past life on other worlds.
References (APA style)
Starr, M. (2025, November 19). *Earliest chemical traces of life on Earth discovered in 3.3-billion-year-old rock*. ScienceAlert.
Wong, M. L., Prabhu, A., Hazen, R. M., et al. (2025). Chemical evidence of ancient life detected in 3.3-billion-year-old rocks. *Proceedings of the National Academy of Sciences*. Advance online publication.
Courtesy: Hashem Al-Ghaili
