Traces of early life in rocks in Australia
SYDNEY — Researchers from the University of New South Wales have for the first time found organic matter in a group of 3.5-billion-year-old fossilized stromatolites known as the Dresser Formation in Western Australia’s Pilbara region.
Stromatolites are a type of rock formed by living organisms and while it was previously suspected that the ancient Dresser Formation was produced by living organisms, it remained unproven, until now.
“This is an exciting discovery. For the first time, we are able to show that these stromatolites are definitive evidence of the earliest life on Earth,” says lead researcher Raphael Baumgartner.
Ever since the discovery in 1980 it has been hotly contested whether the Dresser Formation is actually of biogenic origin, and therefore represented the earliest signs of life on Earth.
To prove the theory, Baumgartner and his team took drill core samples from beneath the stromatolites weathered exterior to where the rock’s microbial past was far better preserved.
“I spent a lot of time in the lab, using micro-analytical techniques to look very closely at the rock samples, to prove our theory,” Baumgartner says.
What they discovered was that the stromatolites were essentially composed of pyrite — or “fool’s gold” — within which there were “preserved coherent filaments and strands that are typically remains of microbial biofilms”.
“I remember the night at the electron microscope when I finally figured out that I was looking at biofilm remains. I think it was around 11 pm when I had this ‘eureka’ moment, and I stayed up until 4 am. I was so excited that I totally lost track of time,” he says.
The breakthrough adds to a growing body of research about the Dresser Formation and how life on Earth may have originated. It has also had an impact on the search for life on Mars, which prompted NASA experts to travel to Australia last month to study the unique site.
“This represents a major advancement in our knowledge of these rocks, in the science of investigating early life in general, and more specifically, in the search for life on Mars. We now have a new target and a new methodology to search for traces of ancient life,” says Van Kranendonk, director of the university’s Australian Centre for Astrobiology.