Life Was Around Much Earlier than Scientists Thought

Life was around much earlier than scientists thought. In fact, according to a new study, oxygen-producing organisms were present on Earth some three billion years ago - a full 60 million years earlier than previous estimates had indicated.

The researchers claim that Earth would not be as it is now if it weren't for the addition of oxygen into the atmosphere, which laid the foundation for more complex life.

Scientists working in India found evidence for chemical weathering of rocks leading to soil formation that occurred in the presence of oxygen.

Using the naturally occurring uranium-lead isotope decay system, which is used to determine the age of substances, geologists claim this took place at least 3.02 billion years ago.

The pattern of chemical weathering preserved in the ancient soils - or paleosols - is compatible with higher atmospheric oxygen levels at that time, say scientists at Trinity College Dublin, who worked alongside geologists at the Presidency University in Kolkata, India.

Organisms that were capable of photosynthesis could only have produced these high oxygen levels.

"This is a very exciting finding, which helps to fill a gap in our knowledge about the evolution of the early Earth," researchers Quentin Crowley said in a press release. "This paleosol from India is telling us that there was a short-lived pulse of atmospheric oxygenation and this occurred considerably earlier than previously envisaged."

Early Earth was very different from what we see today, with an atmosphere plentiful in methane and carbon dioxide and lacking in oxygen. The widely accepted belief is that oxygen didn't come around until 2.4 billion years ago, during what is known as the "Great Oxidation Event."

While microorganisms were undoubtedly present before this evolutionary shift, until now scientists didn't know whether they were yet capable of producing oxygen.

Approximately 3.4 billion years ago there was virtually no oxygen present, but the recent research indicates that it started to accumulate 2.96 billion years ago, moving this event up at least 60 million years, effectively re-writing the evolutionary history books.

The findings were published in the journal Geology.