1.7-billion-year-old fossils reveal a crucial clue to the rise of complex life

Scientists have analyzed over 12,000 fossils recovered from Australian rock formations, providing significant insight into the emergence of complex life forms. Dating back approximately 1.7 billion years, these specimens represent some of the oldest known eukaryotic cells ever discovered. The study highlights a distinct ecological separation based on oxygen availability: complex eukaryotes were exclusively found in oxygenated environments, such as coastal mudflats and open marine settings, while oxygen-depleted areas contained only simpler microbial life. This discovery suggests that the oxygenation of Earth's early environment was a fundamental requirement for the evolution of complex cellular life, offering a clearer picture of how Earth's biosphere transformed over deep time.