Scientists find evidence of oldest life on Earth

By Chris Burns/March 3, 2017 9:09 am EST

A team of researchers in Canada have found what might be the oldest set of fossils in the history of the world. These fossils have been found inside a rock which has been dated at 3.7-billion years old. This set of life forms is rather unique in their age relative to that of the Earth's formation at 4.5-billion years ago.

Billions of years ago, microbes lived and died around the Nuvvuagittuq belt – once a hydrothermal vent on the ocean floor. What scientists have found in the samples picked up at the Nuvvuagittuq Supracrustal Belt (NSB) included evidence the life. This life, they say, lived billions of years ago, living on iron provided by the vents.

Evidence was found of fossils that were likely entombed at a hydrothermal vents at NSB. Studies were done on the inner bits of samples from NSB using a Raman microscope. Inside samples from the site were found carbonate, apatite, and magnetite. These minerals can be found quite often where organic matter is formed. Tiny filaments and tubes added to evidence of ancient bacteria.

The authors of this study suggest that the youngest these specimens could be is 3.77-billion years old. Even then, they'd still be the oldest fossils found by a human being here on Earth.

"The structures are composed of the minerals expected to form from putrefaction, and have been well documented throughout the geological record, from the beginning until today," said study lead, Dr Dominic Papineau (UCL Earth Sciences and the London Centre for Nanotechnology). "The fact we unearthed them from one of the oldest known rock formations, suggests we've found direct evidence of one of Earth's oldest life forms."

"This discovery helps us piece together the history of our planet and the remarkable life on it, and will help to identify traces of life elsewhere in the universe."

Before now, the oldest microbe fossils ever reported were dated at around 3.46-billion years old. Those fossils were found in Western Australia, and may also have been non-biological rock artefacts. As the same might've been suggested about the find sourced in Canada, the team lead by UCL made a point to test the many ways in which these Canadian remains have been made through non-biological methods.

"We found the filaments and tubes inside centimetre-sized structures called concretions or nodules, as well as other tiny spheroidal structures, called rosettes and granules, all of which we think are the products of putrefaction," said Dr Papineau. "They are mineralogically identical to those in younger rocks from Norway, the Great Lakes area of North America and Western Australia."

Temperature and pressure changes in the samples could have had an effect on the contents of the rocks. This study concluded that these and all other possibilities for alternate, non-biological formation of the tubes and filaments in their samples were not likely.

"These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life," said Matthew Dodd (UCL Earth Sciences and the London Centre for Nanotechnology). "Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception."

For more information on this subject, see the scientific publication Nature. There seek the paper "Evidence for early life in Earth's oldest hydrothermal vent precipitates" by authors Matthew S. Dodd, Dominic Papineau, Tor Grenne, John F. Slack, Martin Rittner, Franco Pirajno, Jonathan O'Neil, and Crispin T.S. Little. This paper can be found with code doi:10.1038/nature21377, published online on the 1st of March, 2017.