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An international team reporting in Nature Geoscience has detected an unusual potassium isotope pattern in some of Earth’s oldest rocks—a deficit of potassium‑41 unlike anything seen in modern geology or known meteorites. The anomaly, found in samples from Greenland, Canada, and Hawaiian lavas, withstood multiple tests and simulations, suggesting it could be preserved material from proto‑Earth predating the giant impact. Co‑lead author Nicole Nie called it possible “first direct evidence” of ancient Earth, while noting a matching meteorite could yet surface. The discovery revives a planetary Theseus’s Paradox and underscores how much about Earth’s origins remains unsettled.

Prepared by Olivia Bennett and reviewed by editorial team.