Ancient “living fossils” may reveal how complex life began

A newly discovered microbe living inside ancient stromatolite communities may offer a rare look at how complex life first emerged. Researchers captured the first direct images of an Asgard archaeon physically connected to a bacterium, with the two microbes appearing to exchange nutrients and other compounds. Scientists think similar partnerships billions of years ago may have helped produce the first complex cells.

Ancient “living fossils” may reveal how complex life began. In reality, they are densely packed, layered communities built by microbes. Billions of years ago, before animals and plants existed, stromatolites helped release some of the earliest oxygen into Earth’s atmosphere.

Now, a study published in Current Biology suggests these unusual formations may also preserve clues to another major event in Earth’s history: the emergence of complex life. Associate Professor Brendan Burns, an evolutionary microbiologist at UNSW Sydney, is part of a research team that discovered a previously unknown microbe living in close association with another organism inside these "living fossils." The project, co-led with researchers from the University of Technology Sydney and The University of Melbourne, could help scientists better understand a fundamental evolutionary mystery: how relatively simple cells began cooperating and eventually gave rise to much more complex forms of life. "Stromatolites could be more than ‘just’ a cradle of life where early microbial life flourished," says A/Prof.