When did life first emerge on Earth? Maybe a lot earlier than we thought.
A finding of carbon inside volcanic rock indicates that life could have begun on earth as early as 4.1 billion years ago, when earth was still in a volcanic stage.
Mark Harrison, a geochemistry professor at the University of California, Los Angeles, and his colleagues have found fossil evidence that life on Earth may have began at least 4.1 billion years ago, some 300 million years earlier than previously thought.
Courtesy of Reed Hutchinson/UCLA
The scientific birthday for life on Earth has likely moved way back following the discovery of carbon fossils from the planet's very early volcanic stage.
The finding potentially stretches the date when life began back by 300 million years to 4.1 billion years ago.
“Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking,” Mark Harrison, co-author of the research and a professor of geochemistry at UCLA, said in a news release.
The fact that life – even if it was no more than “the gooey remains of biotic life or anything more complicated" – could have survived at such an early date contradicts the current theory that the early Earth was hot, dry, and unpleasant, Professor Harrison told the Associated Press.
The discovery not only changes how scientists can think about the formation of Earth, but also presents possibilities for other planets in the universe.
“If life arose relatively quickly on Earth, then it could be common in the universe,” S. Blair Hedges of Temple University told the AP. He said the new finding makes sense and actually fits better into the accelerated timeline required for his own genetic research.
The researchers, led by post-doctoral scholar Elizabeth Bell, found the fossil hints inside zircon minerals. The minerals, which they took from western Australia, “capture and preserve their immediate environment, meaning they can serve as time capsules,” according to the UCLA statement.
Inside one of the zircons, the team found graphite, a pure carbon that usually indicates life. They dated the zircon at 4.1 billion years old, and the graphite is older than that.
Harrison told the AP the type of carbon found is what scientists associate with a long-decayed living organism.
“There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon,” Harrison said in the release.
The study’s authors came from the University of California, Los Angeles and Stanford, and it was published Monday in the journal Proceedings of the National Academy of Sciences.
Any theories about such early prehistoric life have their risks, and Harrison told the AP that “this is not smoking gun evidence.” He feels “very confident” that they are headed in the right direction though, he said in a news release.
This report includes material from the Associated Press and Reuters.