The oldest life form has been discovered in Canada, in the form of remains of bacteria from 3,770 million years ago. The findings published in Nature.
The oldest form of life on Earth, discovered in the Nuvvuagittuq Supracrustal Belt (NSB), Quebec, Canada—it constitutes remains of microorganisms whose minimum age is estimated to be 3,770 million years, says the international group of researchers who has documented the findings.
Led by UCL scientists, the team found structures of bacterial origin in quartz layers in the NSB. The latter is known for sheltering sedimentary rocks documented as being among the oldest on Earth. These rocks are thought to have, once, belonged to an iron-rich hydrothermal vent system lying in the depths of the ocean, where the very first life forms of our planet resided around 3,770 and 4,300 million years ago. Some scientists hold the opinion that life started in these hot vents on the ocean floor back when the Earth had been newly created, says first author UCL’s Matthew Dod; the team’s findings support this theory, as they found small filaments and tubes coming from a bacterial source, falling into that period of time, in quartz layers in the NSB.
Upon analysing the remains, it was found that the tubes and filaments were made of a type of iron oxide (or rust) called haematite. It was initially unclear whether they were the products of biological organisms (like bacteria) or non-biological sources (like temperature and pressure fluctuations). When the team scrutinised the microfossils further, they revealed a branching trait that was reminiscent of existing iron-oxidising bacteria living near hydrothermal vents. Also, the haematites were spotted in proximity with graphite and minerals (such as apatite and carbonate) which are contents of biological matter like bones and teeth. Furthermore, the haematite was located in structures thought to be the “products of putrefaction”, explains lead author, Dr Dominic Papineau. According to him, these structures are similar to those in younger rocks, and they are indicative of fossils. The haematite is, thus, thought to have come from biological sources, formed when iron-oxidising bacteria were fossilised in the rock.
“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. 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,” says the author.
To conclude, Dodd says that the findings show that life started on Earth when both Earth and Mars had water on their surfaces, suggesting the possibility of extra-terrestrial life. He is positive that evidence of life on Mars some 4,000 million years ago might be found some day.