The Paleo-Geology of Negative Space

Scientists analyzing rock samples in Australia have found the earliest evidence of life not in items like fossils, but in the absence of such items. A type of rock can be identified as having accreted from sand that became trapped in a thick algae-like mat of bacteria along the shore of an ancient lake, remaining as stone even after the bacteria have died & washed away.

“It’s not just finding this stuff that’s interesting,” says Alan Decho, a geobiologist at the University of South Carolina’s Arnold School of Public Health. “It’s showing that the life had some organisation to it.” Ridges that crisscross the rocks like strands in a spider web hint that primitive bacteria linked up in sprawling networks. Like their modern counterparts, they may have lived in the equivalent of microbial cities that hosted thousands of kinds of bacteria, each specialised for a different task and communicating with the others via chemical signals.

All this just a billion years after our planet formed. As if in confirmation of Aristotle’s suggestion that “Nature abhors a vacuum,” we catch life in the act of organizing even on a planet still trembling from its cataclysmic cosmic coalescence.