Life began earlier than believed, says study

Researchers studying rocks from Greenland announced that they’ve uncovered evidence to show when life on Earth began.Analysis shows the...

Researchers studying rocks from Greenland announced that they’ve uncovered evidence to show when life on Earth began.

Analysis shows the rocks may have been host to our earliest ancestors: single-celled organisms that lived 3.85 billion years ago. If the dating is accurate, the rocks push back the biological record of life on Earth by about 450 million years.

Scientists from the University of Chicago report in Science that the rocks may have once been in a prehistoric ocean, but they were cooked at high temperature under pressure, which drastically modified their chemistry. But by using mass spectrometry, researchers found atomic signatures in the rocks indicating that they’re sedimentary—the type of rock that would form along rivers, in lakes and in oceans—and could host bacteria or some other microscopic form of early life.

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‘‘These are the oldest sediments on earth, so anything they have to tell us is important,’’ said Nicolas Dauphas, the study’s lead author, who is an assistant professor at the university.

The rocks used in the study were collected over the years from the southwest coast of Greenland and Akilia Island, a remote outpost that turned into a research hotspot in the mid-1990s. ‘‘There’s a lot of arguments about these rocks going back and forth,’’ said Meenakshi Wadhwa, a curator at Chicago’s Field Museum and a co-author of the report. —LAT-WP