The history of life on earth may need a significant rewrite. In July an international team reported fossil evidence of multicellular organisms dating back 2.1 billion years. Previously, scientists had believed that the first of these complex creatures did not appear until almost a billion years later, and that single-celled microbes were the only life-form before then.
After recovering more than 250 fossils from clay deposits in western Africa, Stefan Bengtson of the Swedish Museum of Natural History and his collaborators examined some of the relics with a powerful three-dimensional scanner. The fossilized creatures, some of them as large as five inches across, appeared to have an organized internal structure composed of a network of cells, suggesting complexity far beyond the simple bacterial structures Bengtson expected to find.
“This is the first fossil we can hold in our hands and say, ‘Maybe complex life started here,’ ” he notes.