Oxygen, vital for life, was available 3.5 billion years ago. Photosynthesis emerged a billion years earlier than previously believed, challenging our understanding of the formation of complex life on Earth. A groundbreaking discovery is reshaping our concepts of when and how intricate life forms evolved on our planet.
Approximately 2.4 billion years ago, a significant surge in atmospheric oxygen levels occurred, traditionally linked to the emergence of cyanobacteria (precursors of plants). However, a study published in the journal Geobiology in November 2018 suggests that photosynthesis likely evolved much earlier.
Researchers examined the evolution of two key photosynthesis-related proteins, D1 and D2, comparing the genetic code in plants and cyanobacteria. The codes were found to be 70% different, indicating that at least a billion years were required for these proteins to diverge to their current extent. Dr. Tanai Cardona from the Department of Life Sciences at Imperial College London, the main author of the study, emphasizes, “The origin of oxygenic photosynthesis and the ancestors of cyanobacteria are not the same thing. There is a very big gap between them.”
