Breakthrough Discovery: Bacteria Were Breathing Oxygen a Billion Years Earlier Than Expected!

New research reveals that certain bacteria started using oxygen much earlier than scientists thought—nearly 900 million years before the Great Oxidation Event (GOE), which occurred about 2.4 billion years ago. This fresh perspective could change how we understand the evolution of life on Earth, especially regarding respiration and the development of complex organisms.

For a long time, researchers believed that bacteria were unable to tolerate oxygen until the GOE. This event marked a significant moment when oxygen began to fill the Earth’s atmosphere, transforming its environment. However, a new study led by Dr. Adrián Arellano Davín at the Okinawa Institute of Science and Technology shows that some bacterial lineages adapted to oxygen long before this shift.

By analyzing 1,007 bacterial genomes using machine learning, scientists were able to trace back when certain microbes transitioned from anaerobic (non-oxygen) to aerobic (oxygen-using) metabolism. This groundbreaking approach allows better insight into the timelines of bacterial evolution, especially for those groups without fossil records.

Professor Gergely Szöllősi from OIST highlights this method’s value, emphasizing how it clarifies the evolutionary timelines of microbial life. “By combining genomic data, fossils, and geochemical history, we get a clearer picture of how these early organisms lived and evolved,” he said.

The ability to use oxygen gives bacteria a considerable survival advantage. Oxygen-based metabolism is much more efficient than anaerobic processes, allowing bacteria to produce more energy even in small amounts of oxygen. This efficiency likely led aerobic bacteria to expand and diversify rapidly, setting the stage for more complex forms of life.

Dr. Tom Williams from the University of Bristol also points out that modeling microbial traits with machine learning is effective in studying the rise of aerobic metabolisms.

Moreover, this research sheds light on cyanobacteria, the microorganisms known for photosynthesis. Evidence suggests that their ancestors might have developed oxygen tolerance, potentially allowing genes for photosynthesis to evolve simultaneously. This connection redefines how scientists view the timeline of metabolic innovations in early life.

The study connects the dots across various fields—genomic, fossil, and geochemical data—to reconstruct a family tree of bacterial evolution dating back over 3.9 billion years. This comprehensive approach reveals that many aerobic traits emerged even before significant atmospheric changes, albeit in limited environments.

The findings challenge long-held beliefs and open up new avenues for research into life’s early adaptations on Earth. As we continue to explore bacterial evolution, we gain greater insights into the history of our planet and the biological mechanisms that paved the way for life as we know it today.

For further reading on the impact of microbial evolution on Earth’s history, you may refer to this report from NASA.

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