When did life on earth begin? The question continues to stoke the curiosity of scientists, stimulating the search for fossils that provide the only source of direct evidence of when a particular organism existed or how it evolved. Now, J William Schopf of the University of California, Los Angeles, says he has discovered fossils of microbes that predate other such remains by more than 1300 million years (Science, Vol 260, No 5108).

The fossils found in Western Australia suggest that cyanobacteria, a type of bacteria capable of photosynthesising, existed on earth as long as 3465 million years ago.