The Ancient Roots of Complexity

The discovery of a previously unknown microbe living in close association with another organism inside ancient stromatolite communities has sent shockwaves through the scientific community. For decades, researchers have been trying to unravel the mystery of how complex life emerged on Earth. A study published in Current Biology suggests that these “living fossils” may hold the key to understanding one of the most fundamental questions in biology.

Stromatolites and microbial mats have built up layers of microorganisms for billions of years, long before animals and plants existed. These unusual formations have fascinated scientists because they appear to be complex ecosystems that support life in inhospitable environments. The research team, led by Associate Professor Brendan Burns from UNSW Sydney, has been studying these microorganisms for years.

The team collected samples from Shark Bay in Western Australia and isolated a member of the Asgard archaea, an unusual group of microbes believed to be closely related to the ancestors of eukaryotes. This required four or five years of laboratory work just to get the microbes to grow. The researchers used electron cryotomography, a high-resolution 3D imaging method, to capture direct images of an Asgard archaeon physically connected to a bacterium through nanotubes.

This provided visual evidence of what scientists had long suspected: that complex life may have emerged from partnerships between ancient microbes. The implications are staggering. If similar partnerships existed billions of years ago, they could have helped produce the first complex cells. This would be a major breakthrough in our understanding of evolution and the origins of life on Earth.

As Associate Professor Burns notes, “Stromatolites could be more than ‘just’ a cradle of life where early microbial life flourished. They could also tell us how complex life first emerged.” The discovery suggests that even at microscopic scales, cooperation and partnership are essential for survival.

The researchers used deep learning to analyze the microbes’ structures and predict the functions of ancient versions of cellular machinery. This is a powerful tool that could be applied to study other complex systems – from the human brain to ecosystems on other planets.

It’s humbling to remember that life on Earth may have begun in environments as harsh and unforgiving as those found inside stromatolites. The newly identified archaeon, Nerearchaeum marumarumayae, has been named after the ancient Greek sea god Nereus – a fitting tribute to its origins.

The discovery of this ancient microbe offers a window into early Earth’s ecosystems. As we gaze out at the universe, it’s clear that life on our planet is full of mysteries waiting to be unraveled.