Life on a Desolate, Early Earth Began Far Earlier Than Expected 4.1 Billion Years Ago

Life on Earth may have started a staggering 4.1 billion years ago, which is far earlier than scientists once thought. Researchers have found probable evidence for life at that time after studying zircons.

Scientists have long believed that the Earth was dry and desolate about 4.1 billion years ago. In fact, about 3.9 billion years ago the massive bombardment occurred, which formed the moon's large craters. Now, though, researchers have found that life may have existed before this event.

"The early Earth certainly wasn't a hellish, dry, boiling planet; we see absolutely no evidence of that," said Mark Harrison, one of the researchers, in a news release. "The planet was probably much more like it is today than previously thought."

In all, the researchers studied more than 10,000 zircons originally formed from molten rocks or magmas from Western Australia. Zircons are heavy, durable minerals that capture and preserve their immediate environment, acting as tiny time capsules. The researchers then analyzed zircons containing dark specks with Raman spectroscopy. They found that one of the zircons contained graphite, pure carbon, in two locations.

The researchers know that the zircon is 4.1 billion years old, which means that the graphite is slightly older than that. In addition, this carbon contained in the zircon had a characteristic signature that indicated the presence of photosynthetic life.

The findings reveal a bit more about our ancient Earth. In addition, they show that after the bombardment, life must have either survived or restarted almost instantaneously. This, in particular, shows how resilient life truly is.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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