A Japanese research team has uncovered remarkable insights into the ancient circadian clocks of cyanobacteria, revealing how these microorganisms adapted to Earth's evolving rotation period. Published in Nature Communications on May 15th, 2025, the study rewinds over three billion years of molecular evolution.
Cyanobacteria, crucial for the Great Oxidation Event, possess Kai proteins that drive rhythmic cycles. Researchers reconstructed ancestral Kai proteins, discovering that early forms exhibited faster rhythms, matching evidence of shorter days in Earth's past. These ancient clocks effectively preserve a biological record of Earth's rotational evolution.
Around pivotal global events, Kai proteins evolved increased complexity, enhancing the oscillator's precision to match modern Earth's 24-hour rotation. This adaptation ensured maximal photosynthetic efficiency. The findings have implications for synthetic biology and astrobiology, potentially enabling the engineering of cyanobacteria optimized for energy capture on planets with different rotation periods.
"The intertwined evolution of life's internal clocks and Earth's planetary cycles exemplifies the profound coupling between biology and geophysics," said Atsushi Mukaiyama, Associate Professor at Fukui Prefectural University. This could revolutionize strategies for bioengineering organisms adapted to extraterrestrial environments, playing a crucial role in future space exploration.
The research highlights how incremental molecular changes enabled organisms to adapt to planetary-scale environmental cycles. This bridges the microscopic world of protein dynamics with macroscopic geophysical phenomena. The study inspires biologists, geoscientists, and astrobiologists to consider the intricate connections between life and planet in transformative ways.