Stretching the Bounds of Early Life on Earth

Archaea are single-celled critters that lack nuclei, have a methane-based metabolism and are considered one of the oldest life forms on Earth. Many archaea are considered extremophiles that live in hot springs and salt lakes that are hostile to most other life forms, but they’ve also been found in other environments including the gut, mouth and skin of humans.

A group of scientists led by Barbara Cavalazzi (University of Bologna, Italy) writing in the journal Science Advances claims to have found microscopic filaments of archaea in rocks no less than 3.42 billion years old! That’s about one billion years after Earth itself formed and solidified as a respectable planet. If confirmed as bona fide fossils, these would be the oldest archaea discovered to date.

The thread-like fossils come from South African rocks that formed near the extreme conditions of ancient hydrothermal vents. While claimed to be archaea fossils by Cavalazzi and her colleagues, others argue they might be just inorganic mineral substances mimicking cell-like structures and filaments.