Australia – Evidence that life on Earth existed 300 million years earlier than thought was found by geochemists of UCLA. The discovery indicates that life appeared on Earth shortly after the planet formed 4.54 billion years ago —not 4.1 billion years ago as commonly believed.
Scientists analyzed more than 10,000 zircons, formed from molten rocks and magma from Australia. Zircons are minerals, heavy and durable, with the ability to preserve their immediate environment, similar to a time capsule.
Using a Raman spectroscopy, researchers identified dark specks contained in 656 zircons, analyzing 79 of them in order to unveil the molecular and chemical structure of ancient microorganisms. What were they looking for? Carbon, the key component of life, contained on one of the analyzed zircons in the form of graphite.
“The first time that the graphite ever got exposed in the last 4.1 billion years is when Beth Ann and Patrick (team members) made the measurements this year,” Harrison stated.
Researchers believe that, with the “right ingredients”, such as carbon, life on Earth could have begun almost instantaneously, shortly after the bombardment of the inner solar system that formed the moon’s large craters 3.9 billion years ago. Some experts argue that all life on the planet died during the bombardment, meaning that it must have restarted pretty fast.
Mark Harrison, co-author of the study published in the Proceedings of the Natural Academy of Sciences, said, “The early Earth certainly wasn’t a hellish, dry, boiling planet; we see absolutely no evidence for that. The planet was probably much more like it is today than previously thought,” according to the press release.
Harrison and his team are very confident about the age of these microorganisms. They say that there is no better evidence than the zircons and that nobody has offered a consistent explanation for the presence of graphite on these minerals.
Graphite founded in the minerals is even older than the zircons containing them, as they can assure —based on measurements of uranium— that the zircon is at least 4.1 billion years old.
The study suggest the idea that “life in the universe could be abundant”. It seems that on this planet, life appeared quickly, but the evolving process probably took millions of years.
The carbon contained in the zircon has a special signature: It indicates the presence of photosynthetic life, a proof hard to ignore, inviting us to think differently about the life on Earth.
Source: Proceedings of the Natural Academy of Sciences