3.7B-year-old fossil makes life on Mars look more likely
Discovery throws open ‘window back in time’
And you thought that slime in the bottom of your fridge was ancient.
Scientists have found the oldest known remnant of life, a fossil dating back a staggering 3.7 billion years.
If confirmed, the date would support the theory that life took root in the blink of an eye after the planet’s birth. Such early life also would make life on Mars seem less of a long shot.
The newfound remains consist of a layer of rock that to the untutored eye looks, well ... like a layer of rock.
Scientists say it’s in fact a stromatolite, a mineral structure created by the busywork of countless microorganisms. These microbes thrived in a shallow sea bathing a still young and fresh Earth, according to a study in this week’s Nature.
Previous chemical analysis of old rocks hinted life arose by 3.7 billion years ago, but that evidence was open to question, says study co-author Allen Nutman of Australia’s University of Wollongong. “What we’ve done is produce something tangible,” Nutman says, “an actual fossil record (that is) evidence for life at those times.”
The researchers “were able to see evidence for life in a way that I had never expected,” says Texas A&M University’s Michael Tice, who was not associated with the study. “We have a much better window back in time, thanks to what these folks did.”
The fossil was discovered in a barren stretch of Greenland that researchers have explored for about three decades. Heavy spring rains recently melted a snow patch, exposing a layer of rock.
The rock layer contained a level bottom, but the top was jagged. Standing less than 2 inches high, the layer resembled a miniature mountain range in profile. After having read about such objects, “we immediately knew what we were looking at,” Nutman says.
The rock’s structure mimics that of a 2 billion-year-old object widely accepted as a stromatolite, says study co-author Martin Van Kranendonk of Australia’s University of New South Wales. Chemical clues hint that microbes played a role in the object’s formation.