Groundbreaking discovery pushes back the timeline of photosynthetic structures and offers insights into Earth’s oxygenation process.
Researchers led by Emmanuelle Javaux at the University of Liège in Belgium have uncovered fossilized cyanobacteria dating back 1.75 billion years, containing the oldest evidence of photosynthetic structures known as thylakoids. This groundbreaking finding not only extends the fossil record of thylakoids by 1.2 billion years but also provides essential clues about the evolution of photosynthesis and its role in Earth’s atmospheric changes.
Main Findings:
- Fossilized Cyanobacteria with Thylakoids: The study focused on fossils from three global sites—Australia, Canada, and the Democratic Republic of the Congo. The 1.75-billion-year-old cyanobacteria from Australia and the billion-year-old samples from Canada displayed thylakoids, membrane-bound sacs crucial for photosynthesis.
- Timeline Shift: This discovery challenges previous notions about the evolution of thylakoids. The newfound 1.75-billion-year-old fossils suggest that these structures evolved much earlier than the previously identified oldest thylakoid fossils, which were about 550 million years old. The pushback in the fossil record extends our understanding by 1.2 billion years.
- Cyanobacteria and Oxygen Accumulation: The presence of thylakoids in ancient cyanobacteria strengthens the connection between these microorganisms and the accumulation of oxygen in Earth’s atmosphere around 2.4 billion years ago. This aligns with the widely accepted belief that cyanobacteria played a pivotal role in triggering the Great Oxygenation Event.
Details of the Research:
- Researchers analyzed fossilized cyanobacteria, each less than a millimeter in size, from Australia, Canada, and the Democratic Republic of the Congo.
- The fossils were embedded in resin, sliced into thin sections, and examined under an electron microscope.
- Thylakoids were identified in the Australian and Canadian samples, marking the oldest known fossil evidence of these structures.
Implications for the Evolution of Photosynthesis:
- Evolutionary Timeline: This discovery provides valuable insights into the evolution of photosynthesis, suggesting that thylakoids may have evolved around 2.4 billion years ago.
- Great Oxygenation Event: The link between thylakoids and the rise of oxygen in Earth’s atmosphere further supports the hypothesis that cyanobacteria played a key role in the Great Oxygenation Event.
Additional Points:
- Not All Cyanobacteria Have Thylakoids: The discovery emphasizes the significance of thylakoids in understanding the evolution of cyanobacteria, as not all of them possess these structures.
- Direct Evidence: While geochemical evidence hinted at the existence of photosynthesis before 2.4 billion years ago, the fossilized thylakoids provide direct evidence, enhancing our understanding of early life on Earth.
In conclusion, the revelation of 1.75-billion-year-old thylakoid-containing fossils represents a pivotal discovery in the study of Earth’s history. By unraveling the mysteries of photosynthesis evolution, this research offers a crucial chapter in understanding how life on our planet transformed over billions of years.