Topic: Biology

Scientists found evidence that some ancient microbes may have used oxygen hundreds of millions of years before it became a stable part of our atmosphere. This changes our understanding of how life evolved on Earth.

Today, we breathe in oxygen all the time. But for most of Earth's history, there was no oxygen in the air. Oxygen only became a permanent part of our atmosphere about 2.3 billion years ago. Now, researchers at MIT have discovered that some ancient microbes may have learned to use oxygen hundreds of millions of years before that. This is important because it helps us understand how life evolved on Earth.

The scientists studied an enzyme called heme copper oxygen reductase. This enzyme allows organisms to consume oxygen. They found that this enzyme first evolved during the Mesoarchean era, which was hundreds of millions of years before oxygen became a stable part of our atmosphere.

The researchers also looked at cyanobacteria, tiny microorganisms that produce oxygen as a byproduct of photosynthesis. These microbes emerged around 2.9 billion years ago and were likely generating oxygen for hundreds of millions of years before the Great Oxidation Event. So what happened to all that early oxygen? The scientists think that chemical reactions with rocks removed much of it from the environment, and some organisms may have also consumed it.

This discovery changes our understanding of how life evolved on Earth. It shows us that life is incredibly innovative at all periods in Earth's history.

Why It Matters

Understanding how life evolved on Earth can help us better understand ourselves and our place in the world. This discovery also highlights the importance of oxygen in supporting life as we know it.

Key Facts

• Ancient microbes may have used oxygen hundreds of millions of years before it became a stable part of our atmosphere.
• The enzyme heme copper oxygen reductase first evolved during the Mesoarchean era, which was hundreds of millions of years before oxygen became a stable part of our atmosphere.
• Cyanobacteria emerged around 2.9 billion years ago and were likely generating oxygen for hundreds of millions of years before the Great Oxidation Event.
• Chemical reactions with rocks may have removed much of the early oxygen from the environment, and some organisms may have also consumed it.
• This discovery changes our understanding of how life evolved on Earth.

Key Terms

Heme copper oxygen reductase

An enzyme that allows organisms to consume oxygen

Implications

Understanding how life evolved on Earth can help us better understand ourselves and our place in the world. This discovery also highlights the importance of oxygen in supporting life as we know it.