University of California scientists find evidence that life on earth may have begun 4.1 billion years ago

Geochemists working at the University of California Los Angeles (UCLA) announced on October 19, 2015, that they had uncovered evidence pushing back the timeline of life on Earth to at least 4.1 billion years ago. This was a remarkable leap — roughly 300 million years earlier than anything previous research had suggested. Perhaps most strikingly, the finding pointed to life emerging not long after our planet itself came into being some 4.54 billion years ago.

The breakthrough came from an unlikely source: a 4.1 billion-year-old zircon crystal. By closely studying the carbon isotopes trapped within graphite preserved inside this ancient mineral, the UCLA research team determined they were looking at a signature of early life. Their conclusion directly challenged the long-held view, supported by earlier research, that life on Earth didn't get started until around 3.8 billion years ago.

What made this finding such a game-changer was its implications for how quickly life took hold on our young planet. Where scientists had previously placed the origins of life at about 3.8 billion years ago, this discovery moved the clock back dramatically to around 4.1 billion years ago. It suggested that early life forms — microbes among them — were already growing and evolving shortly after Earth formed approximately 4.54 billion years ago.

To reach their conclusion, the research team sifted through a staggering collection of over 10,000 zircons. These heavy, remarkably durable, diamond-like minerals act as natural time capsules, locking away materials from the distant past. Beyond the evidence of ancient life, the researchers also identified the earth's oldest-known rock fragment, dating back roughly 4.4 billion years.

The path from 10,000 zircon samples to a single stunning discovery was painstaking. Scientists whittled the collection down to just 79 candidates in their search for graphite. Of all those samples, only one tiny zircon fragment actually contained graphite inclusions — and it measured approximately half the width of a human hair strand.