According to shocking new findings, life emerged on Earth 4.1 billion years ago—270 million years earlier than previous research led us to believe. If the conclusions of the study are accurate, life arrived shortly after Earth formed 4.54 billion years ago, suggesting that life is most certainly abundant elsewhere in the universe.
“The faster life arises on Earth, the more varied and possibly extreme are the conditions in which it can do so elsewhere and be sustained,” co-author of the study Mark Harrison, a geochemist at the UCLA, told reporters at Live Science.
The researchers analyzed more than 10,000 zircons (heavy, durable minerals related to cubic zirconia) that formed from molten rock in what is now Western Australia. As zircons form, they capture and preserve the materials in their immediate environment, capturing them in time.
In the new study, a group of scientists identified 656 zircons containing dark specks, and focused in on 79 whose appearance suggested they could contain graphite. Graphite is made of pure carbon and is believed to be the key component of life on Earth. Scientists believe that analyzing carbon isotope levels in ancient graphite could give insights into whether life was alive at the time of the oldest-known rock fragment, dating back 4.4 million years.
“It was nerve-wracking to manipulate the sole tiny zircon fragment—about half the width of a hair on your head—containing the graphite inclusions,” Harrison commented.
The ratio of uranium-to-lead isotopes in the zircon suggests that it is 4.1 billion years old.
“Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking,” he continued.
The zircon has a high ratio of carbon-12 to carbon-13, which suggests a biological origin for this carbon—likely the result of life-forms that photosynthesize.
“Life on Earth may have started almost instantaneously. With the right ingredients, life seems to form very quickly,” Harrison concluded.
This idea challenges the widely believes theory that the early Earth was dry and desolate. However, as Harrison notes, “our view of the first many hundreds of millions of years of Earth history as a roiling, lifeless and continent-free world was actually based on zero observational evidence.”
The new finding also suggests that life existed before the Late Heavy Bombardment, the series of cosmic impacts that first formed the moon’s giant craters. If life died on Earth during this bombardment, then life must have resumed very quickly.
Though the latest research probably raises more questions than it does answers, it is difficult to dispute.
“Nobody has offered a plausible alternative explanation for the graphite of non-biological origin into a zircon,” Harrison argued.
What do you think of these new findings? Does this challenge everything we know about life on Earth?