How did life on Earth begin? Scientists make big discovery in tiny structures

The research, conducted at the Early Life Traces & Evolution laboratory of ULiege's Astrobiology Research Unit, involved meticulous examination of enigmatic microfossils known as Navifusa majensis (N.majensis) found within the ancient shales.

In Short

• It propels the fossil record of thylakoids back by a staggering 1.2 billion years
• The research was conducted at the Early Life Traces & Evolution laboratory
• This discovery marks a pivotal moment in the scientific community

In a new study, researchers from the University of Liege have made a monumental discovery that sheds new light on the ancient history of life on Earth.

The team, led by Professor Emmanuelle Javaux, has identified the oldest known microstructures in fossil cells — thylakoid membranes — dating back an astonishing 1.75 billion years.

This finding, published in the journal Nature, propels the fossil record of thylakoids back by a staggering 1.2 billion years and offers fresh insights into the evolution of cyanobacteria and their significant role in oxygenating our early planet.

The research, conducted at the Early Life Traces & Evolution laboratory of ULiege's Astrobiology Research Unit, involved meticulous examination of enigmatic microfossils known as Navifusa majensis (N.majensis) found within the ancient shales of the McDermott Formation in Australia, as well as formations in DRCongo and arctic Canada.

Through ultrastructural analyses of fossil cells from two of these locations, the team was able to confirm the presence of internal membranes with characteristics unmistakably indicative of thylakoid membranes—the sites of oxygenic photosynthesis.

This profound discovery not only identifies N. majensis as a fossil cyanobacterium but also significantly impacts our understanding of the timeline of life's evolution. Cyanobacteria with thylakoid membranes are now known to have been present during the Great Oxygenation Event (GOE) approximately 2.4 billion years ago, a pivotal period when Earth's atmosphere began to accumulate oxygen, altering the course of life's development.

Professor Javaux explains, "The oldest known fossil thylakoids date back to around 550 million years. The ones we have identified therefore extend the fossil record by 1.2 billion years." She adds, "The discovery of preserved thylakoids in N. majensis provides direct evidence of a minimum age of around 1.75 billion years for the divergence between cyanobacteria with thylakoids and those without."

The implications of this discovery are vast. It opens up the possibility of finding even older cyanobacterial fossils with thylakoids, which could further elucidate the role these structures played in Earth's oxygenation.

Moreover, it allows scientists to explore the influence of dioxygen on the evolution of complex life, including the origins and diversification of algae that possess chloroplasts derived from cyanobacteria.

Javaux concludes with a reflection on the significance of microscopic life, stating, "Studying its fossil record using new approaches will enable us to understand how life evolved over at least 3.5 billion years." Her enthusiasm extends beyond our planet, as she notes that such research could guide the search for traces of life elsewhere in the cosmos.

This discovery marks a pivotal moment in the scientific community, offering a deeper comprehension of the ancient processes that shaped life on Earth and potentially beyond.

Published By:
Sibu Kumar Tripathi
Published On:
Jan 9, 2024