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PILBARA, Australia — Researchers have discovered the oldest-known fossils on the planet: fossilized bacteria from 3.5 billion years ago, before even oxygen existed on Earth.
Scientists analyzing Australian rocks discovered traces of bacteria from about 1 billion years after Earth was formed.
"Those are our oldest ancestors," Old Dominion University biogeochemist Nora Noffke told the West Australian.
The fossils are not petrified body parts, but rather textures on the surface of sandstone thought to have been made by past organisms. Noffke and her team measured the carbon that makes up the rocks to look for the signature of organic carbon that came from a living being: a great amount of carbon-12, versus carbon-13.
"It's always nice to have a number of different lines of evidence, and you definitely want to see organic carbon," said geomicrobiologist John Stolz of Duquesne University in Pittsburgh.
The researchers told the Sydney Morning Herald the discovery could help researchers looking for the building blocks of life on other planets by helping us further understand the formation of life on our own planet.
Crisscross patterns in the sandstone hint at sprawling networks of bacteria that may have lived in microbial cities, each with a different task, according to Alan Decho, a geobiologist at the University of South Carolina's Arnold School of Public Health.
"It's not just finding this stuff that's interesting," he said. "It's showing that the life had some organization to it."
