The discovery of the microbial fossils, in Canada, has been made by scientists from University College London. The discovery takes the form of tiny filaments and tubes formed by bacteria that once lived on iron. The find was made within quartz layers recovered from the Nuvvuagittuq Supracrustal Belt, which is located in Quebec. The Nuvvuagittuq Supracrustal Belt is a rich source of fossils and it contains the oldest sedimentary rocks known on Earth. These rocks were formed from an iron-rich deep-sea hydrothermal vent system. This are provided the habitat for the first life forms on the planet, dating to around 3,770 and 4,300 million years ago.
The discovery is not only important in terms of the dating of the fossils it also adds support to the theory that life on Earth originated from hot, seafloor vents. The earliest life forms – bacteria – emerged not long after Earth’s formation.
The new discovery pre-dates the previous earliest discovered microfossils. These were found in Western Australia and were dated at around 3,460 million years. These microfossils have also been a point of dispute with some scientists believing them to be artifacts in the rocks of a non-biological origin. This area of science is termed micropaleontology, and microfossils are a common feature of the geological record, from the Precambrian to the Holocene.
The new Canadian find was examined carefully to see if the haematite tubes and filaments were likely to have been of a biological or non-biological origin. To assess this various methods of formation were studied, including the effects of temperature and pressure. These analyses pointed to the fossils being of biological origin. One particular aspect which swayed things was the haematite structures (the mineral form of iron(III) oxide) having the same characteristic branching of iron-oxidising bacteria found near hydrothermal vents today. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots.
Discussing this, lead researcher Dr Dominic Papineau explains: “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.”
Speculating further the researchers state that the discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces. This raises the possibility of extra-terrestrial life on Mars, or at least life forms that existed sometime in the past on the red planet.
The discovery has been reported to the journal Nature. The research is titled “Evidence for early life in Earth’s oldest hydrothermal vent precipitates.”
