Ancient rocks in northwestern Canada may contain the oldest evidence of life on Earth.
Scientists have discovered remains of microorganisms that likely thrived around 3.8 billion years ago near volcanic vents on the seafloor, according to a study published Wednesday in Nature.
Iron-dwelling bacteria left behind tiny, rusty filaments and tubes, which were found encased in layers of quartz in the Nuvvuagittuq supracrustal belt near Quebec.
"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," Dominic Papineau, the study lead and a lecturer at University College London (UCL)'s Earth Sciences department, said in a press release.
Image: Dominic Papineau
"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," he said. Most likely, that means searching for evidence of life on Mars.
Prior to this study, the oldest known microfossils were found in western Australia and dated at around 3.5 billion years ago. Scientists also uncovered a set of 3.7 billion-year-old microbial remains found in Greenland, although the evidence for life in the Arctic formations is not nearly as solid as that found in Australia.
Scientists from Canada, the U.K., the United States, Norway and Australia teamed up on the Canadian fossil study.
They searched for fossil evidence in the Nuvvuagittuq belt because it contains some of the Earth's oldest known sedimentary rocks, which were likely formed by deep-sea hydrothermal vents that spewed out scalding water laden with minerals, including iron.
These vents may have hosted bacterial life between 3.8 billion and 4.3 billion years ago, not long after the Earth formed.
Scientific evidence suggests our planet had liquid water at its surface around this time — and possibly so did Mars.
Image: matthew dodd
The fact that bacterial life was gushing from deep-sea vents in Earth's earliest years suggests the same might've been happening on the red planet, said Matthew Dodd, a doctoral student at the London Center for Nanotechnology and the study's first author.
The fossil find in Canada poses "exciting questions for extra-terrestrial life," he said in the press release. "We expect to find evidence for past life on Mars [4 billion] years ago, or if not, Earth may have been a special exception."