Friday, 10 April 2026, 6:57 pm
Article: The Conversation
Brendan
Paul Burns, UNSW
Sydney and Kymberley
Oakley, Indigenous
Knowledge
On the shores of the west
coast of Australia lies a window to our past: the
stromatolites and microbial mats of Gathaagudu (Shark Bay).
To the untrained eye they look like a collection
of rocks and slime – but they are in fact teeming with
microbial life. And these stromatolites are living
“relics” of ancient ecosystems that thrived on Earth
billions of years ago.
If you wade past, it feels
like you’re walking back through time. In fact, the first
bubbles of oxygen that filled the atmosphere on early Earth
likely came from ancient
stromatolites. You could say we owe our very existence
to these piles of rocks.
So, what other secrets of
our past could these ecosystems tell us? Through decades of
research,
we know how early life has woven its path through these
“living rocks”. But most recently our team embarked on
the greatest genealogy search of them all: searching for our
great microbial ancestors, the Asgard archaea.
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And
in a new paper,
published today in the journal Current Biology, we
report how this search led to the discovery of a key clue
that could help explain how complex life evolved on Earth.
A field
of stromatolites in Shark Bay, Western Australia.
Brendan
Burns
The cells that comprise complex
life
Asgard archaea were originally named after
Norse gods. This fascinating group of microbes sits on the
cusp of one of the most significant events in the evolution
of life: the origin of the complex cells that make up plants
and animals, known as eukaryotes.
Evidence
suggests Asgard archaea are the closest relatives of
eukaryotes. And that on an early Earth it was the
“marriage” of an ancient Asgard archaeon and a bacterium
that led to the first eukaryotes.
They formed an
ancient partnership. They shared resources and physically
interacted, leading to the first complex cells. Like a Romeo
and Juliet tale of two distant families coming together,
Asgard archaea and bacteria decided it was time to break
from traditional family values.
But we have never
seen a model of how this may have occurred. Until
now.
Holding up a mirror to the ancient
past
Our team used the mats of Shark Bay as a
“seed” to establish cultures of these ancient microbes.
We are one of only four groups worldwide to achieve this,
through years of research with a dedicated team of graduate
students nurturing the Asgards like offspring.
But
the Asgards were not alone. We found them together with a
sulphate-loving bacterium. Could this be a model of how
complex life may have started on a primitive Earth?
We began by sequencing the Asgards’ DNA to
decipher exactly how these microbes tick at the genetic
level. We also used artificial intelligence to model how
proteins could have behaved in a world before eukaryotes.
Evidence suggested these two microbes were sharing
nutrients. In other words, they were cooperating.
But we wanted to delve deeper. What do our great
microbial ancestors look like? Here we turned to electron
cryotomography, a high-resolution imaging approach that
allowed us to observe cells and structures at a nanometre
scale.
And here we showed – for the first time
– an Asgard archaeon and a bacterium directly interacting.
Tiny nanotubes were connecting the two organisms – perhaps
reflecting what their great-ancestors did on an early Earth
that ultimately led to the explosion of complex life as we
know it.
Microbial mat from Gathaagudu (Shark Bay,
Australia). Inset: Microscopic image showing Asgard archaeon
and bacterium derived from these mats interacting as a model
for evolution of complex cells.
Iain
Duggin/Bindusmita Paul/Debnath Ghosal/Matthew
Johnson/Brendan Burns.
Weaving western
science with Indigenous knowledge
This was a major
discovery – one that originated in Gathaagudu, a World
Heritage Site with significant environmental and cultural
values.
Aboriginal people first inhabited
Gathaagudu over 30,000
years ago. We wanted to recognise and celebrate the
language of the Malgana people, one of the traditional
language groups of Gathaagudu. We also wanted to connect
western science with Indigenous Knowledge in a meaningful
way.
To this end and working closely with the
world’s foremost Malgana language expert, Kymberley
Oakley, and Aboriginal elders, a name was granted for our
novel Asgard archaeon from the language of the Malgana
people: Nerearchaeum marumarumayae. The species
name – marumarumayae – is derived from the
Aboriginal language of the Malgana people, meaning
“ancient home”, a reference to stromatolites being of
ancient origin in Earth’s history.
Weaving
Aboriginal language into the naming of our new microbe
represents a fitting connection between unique Aboriginal
culture in Australia and the ancient microbe discovered that
calls the mats of Gathaagudu “home”.
Gathaagudu
is under threat from global
change, from increased heatwaves, cyclonic events and
human activity. And among the values to preserve and
conserve are the significant Aboriginal connections as well
as the trails of life going back through evolutionary time.
With our study we have peered into our past. And
maybe like the Montagues and Capulets of Shakespeare, we see
distant families of microbes coming together to bridge the
divide and ultimately form the early eukaryotes that
eventually led to us: a fragile branch on the evolutionary
tree of life.
Brendan
Paul Burns, Associate Professor, School of Biotech &
Biomolecular Science, UNSW
Sydney and Kymberley
Oakley, Indigenous language expert, Indigenous
Knowledge
This article is
republished from The
Conversation under a Creative Commons license. Read the
original
article.