Researchers have discovered 2.1 billion year-old fossils that answer new questions about the origins of life on Earth.

A mass fossil discovery in Gabon has provided proof of the existence of multicellular organisms 2.1 billion years ago, challenging established ideas about the transition from single- to multi-cell organisms. The finding, out of CNRS/Universite de Poitiers, is published in the most recent edition of Nature.

Initial Earthly life came in the form of single-celled prokaryotic organisms roughly three and a half billion years ago. Increased complexity ensued, with eukaryotes (single-celled structures which, unlike pokaryotes, contain a nucleus) developing approximately 2 billion years ago. There is however, little else known about the development of life in this embryonic phase, a period dubbed the Porterozoic era, dated from approximately 3.5 to 600 million years ago.

In Gabon, while digging in 2.1 billion-year-old sediment, the interdisciplinary French research team collected more than 250 fossils which, being 10 to 12 centimeters long, were too large and complex to be pokaryotes or eukaryotes.  They often collected the specimens in concentrated blocks across scattered terrain suggesting that the organisms lived in colonies in a shallow marine environment.

These findings constitute a milestone in understanding life's origins. Previously, the oldest complex life forms were dated from approximately 600 million years ago. The new discovery moves the timeline of complex life back 1.5 billion years, challenging previously held norms regarding organic diversity.