Here’s what kick-started life on Earth

By Mark Waghorn via SWNS

Life was kick-started by oxygen deep inside the Earth's crust, according to new research.

The ancient source fueled evolution around 3.5 billion years ago - before the birth of photosynthesis.

Hydrogen peroxide is a toxic form released through cracks in the crust, say scientists. Even a tiny quantity can kill a human, but it helps microbes to breathe.

The gas is generated from rocks during the movement of geological faults.

Lead author Jordan Stone, a Masters student at Newcastle University, said: "Previous research has suggested small amounts of hydrogen peroxide and other oxidants can be formed by stressing or crushing of rocks in the absence of oxygen.

"This is the first study to show the vital importance of hot temperatures in maximizing hydrogen peroxide generation."

Earth's oxygen-rich atmosphere was built by microscopic organisms called cyanobacteria - commonly known as blue-green algae.

They generated energy from sunlight. How their even more primitive ancestors survived
has been a mystery - until now.

Hydrogen peroxide was key in the emergence from an oxygen-free world to one in which complex creatures - including ourselves - could emerge.

It feasibly influenced the very origin of life in hot environments on the early planet prior to the advent of photosynthesis.

Tectonically active regions not only generate earthquakes but riddle the subsurface with fissures.

They are lined with highly reactive rocks containing imperfections, or defects. Water can then filter down and react.

In lab experiments, Stone and colleagues simulated conditions by crushing granite, basalt and peridotite - rock types present in the early crust.

These were then added to water under well-controlled oxygen-free conditions at varying temperatures.

Substantial amounts of hydrogen peroxide - and as a result, potentially oxygen - were generated at temperatures close to the boiling point of water.

The temperature of hydrogen peroxide formation overlaps the growth ranges of some of the most heat-loving microbes on Earth called hyperthermophiles.

These include ancient oxygen-using microbes near the roots of Charles Darwin's Universal Tree of Life.

Principal investigator Dr. Jon Telling, also from Newcastle, said: "This research shows that defects on crushed rock and minerals can behave very differently to how you would expect more 'perfect' mineral surfaces to react.

"All these mechanochemical reactions need to generate hydrogen peroxide, and therefore oxygen, is water, crushed rocks, and high temperatures.

"They were all present on the early Earth before the evolution of photosynthesis and could have influenced the chemistry and microbiology in hot, seismically active regions where life may have first evolved."

The study is in the journal Nature Communications.