Science Frontiers · deep-mysteries

Filed by Dr. Vera Quark

Scientists may have solved a 2.3-billion-year-old mystery about how Earth maintained enough oxygen to support life. Ancient rocks reveal that phosphorus recycling in the oceans created a self-sustaining cycle that helped keep oxygen levels high, even as the planet underwent dramatic environmental changes. The discovery challenges assumptions about Earth's early atmosphere and raises new questions about why complex life took so long to emerge.