According to a study, microscopic animals have been found that may
represent the 'oldest vestiges' of the human ancestry.
In rocks from northern Australia that are billions of years old,
researchers found a "lost world" of ancient species that they believe might
alter how people think about their first ancestors.
According to the researchers, the tiny organisms, known as Protosterol
Biota, thrived in Earth's rivers some 1.6 billion years ago and are members
of the eukaryote family of organisms.
Eukaryotes have a sophisticated cell structure that contains a nucleus, the
"control and information center," and mitochondria, the "powerhouse" of the
cell.
Fungi, plants, animals, and single-celled creatures like amoebas are
examples of contemporary eukaryotes.
The last eukaryotic common ancestors (LECA), who lived more than 1.2
billion years ago, are the ancestors of humans and all other nucleated
organisms.
The latest findings "appear to be the oldest remnants of our own lineage -
they lived even before LECA," said Benjamin Nettersheim, an Australian
national university (ANU) PhD graduate who is currently stationed at the
University of Bremen in Germany.
These extinct animals were common in marine habitats all across the world
and likely influenced ecosystems for a significant portion of Earth's
history.
The Protosterol Biota was identified after ten years of research by ANU
scientists, and the findings were published in Nature on Thursday.
The Protosterol Biota were more complicated than bacteria and likely
bigger, according to ANU's Jochen Brocks, who discovered the finding
alongside Nettersheim. However, it is unknown what they looked like.
The professor stated in a statement, "We believe they may have been the
first carnivores on Earth, hunting and consuming microorganisms.
For the study, scientists from Australia, France, Germany, and the United
States looked at fossilized fat molecules discovered within a rock that
originated at the ocean floor close to what is now Australia's Northern
Territory.
The oldest biomarker-bearing rocks on Earth can be found in northern
Australia, which also has some of the best preserved sedimentary rocks from
the mid-Proterozoic era.
"The molecular fossils entrapped in these ancient sediments allow unique
insights into early life and ecology," stated Nettersheim.
The scientists discovered that the chemicals had an ancient chemical
structure that suggested the existence of early sophisticated organisms that
arose before LECA and have since gone extinct.
We would have never been aware that the protosterol biota existed if not
for these compounds. Our new finding disproves the widespread belief that
early waters were dominated by microorganisms, Nettersheim added.
According to Brocks, the species probably flourished between 1.6 billion
and 800 million years ago.
The Tonian Transformation marks the conclusion of this stage in Earth's
evolutionary history and marks the beginning of the emergence of more
complex species like fungus and algae. However, the precise date of the
Protosterol Biota's extinction is uncertain.
According to Brocks, "The Tonian Transformation is one of the most
significant ecological turning points in the history of our planet."
Perhaps the Protosterol Biota had to go a billion years earlier to create
room for contemporary eukaryotes, just as the dinosaurs had to go extinct so
that our animal ancestors could grow big and numerous.
