New Study Reveals: Oxygen Metabolism Existed on Earth Long Before the Great Oxidation Event

The Great Oxidation Event, happening around 2.4 billion years ago, transformed Earth into a place rich in oxygen. This change was crucial for living organisms. Interestingly, some bacteria were already using oxygen for respiration long before this event.

An international team of researchers used genetic data and machine learning to study the earliest aerobic bacteria. They found that while most bacteria began using oxygen after the Great Oxidation Event, some had adapted to aerobic life about 900 million years earlier.

Among 1,007 bacteria species examined, over 80 showed genetic changes that allowed them to use oxygen. Estimates suggest these transformations began before oxygen reached high levels in the atmosphere. “At least three transitions predated the Great Oxidation Event,” the researchers noted, suggesting that aerobic respiration may have evolved earlier than we thought.

These early oxygen-using bacteria could have laid the groundwork for others to develop photosynthesis, a process that releases oxygen from water and carbon dioxide. As oxygen levels rose, these bacteria thrived, allowing them to adapt faster than their anaerobic counterparts. They played a crucial role in changing the survival game on Earth, which eventually led to diverse life forms, including us.

There are still questions about how the genes of modern bacteria connect to those ancient ones. But the researchers believe they have evidence strong enough to support their findings. They were able to correlate bacterial evolution with changes in Earth’s oxygen levels, filling in gaps where fossil records may be lacking.

Interestingly, these studies indicate that the evolution of cyanobacteria was a gradual process, with roots extending far back into Earth’s history. These findings highlight how interconnected life and Earth’s environment are, and the team hopes their methods can help uncover more about early life traits in the future.

This research provides a glimpse into how much we owe to those tiny microbes. Resources like the full study published in Science offer more detailed insights into this fascinating topic.

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