As many previous studies have shown, the way we breathe today depends heavily on the Great Oxidation Event that occurred about 2.3 billion years ago - an event that prompted our microbial ancestors to make the leap to more complex forms.

The Great Oxidation Event was an explosion of O ₂ in the atmosphere due to biological processes.

What triggered the biological processes that changed the planet so radically remains a mystery. But 2.75-billion-year-old rocks in Zimbabwe offer a clue.

According to SciTech Daily, the research team led by Dr. Ashley Martin of Northumbria University (UK), including experts in geology, microbiology and geochemistry from the UK - Germany - South Africa, examined ancient stromatolite blocks preserved in southern Zimbabwe.

Stromatolites are layered sedimentary structures formed by the activity of microorganisms, primarily cyanobacteria.

They are considered to be among the oldest fossils on Earth, providing important evidence of early life.

They found that nitrogen isotope values ​​from ancient shallow-water stromatolites were higher than those from deeper-water stromatolites.

This suggests that ammonium, which is reduced nitrogen, accumulates in deep waters and is carried into shallow waters by upwelling, the movement of nutrient-rich water from deep regions toward the ocean surface.

Writing in the scientific journal Nature Communications , the authors explain that a large ammonium reservoir would have been beneficial to early life, providing a source of nitrogen needed for biological processes.

These conditions could only occur in an ocean depleted of dissolved oxygen but strongly influenced by volcanoes or hydrothermal systems.

Some previous evidence suggests that our planet was highly volcanically active at the time these sedimentary rocks formed, 2.75 billion years ago.

Today, volcanoes might be catastrophic. But 2.75 billion years ago, they provided the conditions needed for early bacteria to spread and grow in population, potentially driving biological innovations and paving the way for the Great Oxidation Event.