Atacama Desert Reveals Intriguing Ecosystem: Crucial clues about the origin of life on Earth emerge
The identification of traces of the earliest forms of life on our planet occurred in a lagoon ecosystem considered "unique in the world", located in Argentina. This discovery was made possible through the analysis of satellite images of the region.
Stromatolites at the bottom of a lagoon in Puna de Atacama, Argentina — Photo: Bryan Hinek
A team of scientists reports having identified traces of the earliest forms of life on our planet. The discovery occurred in a lagoon ecosystem considered "unique in the world", located in Puna to Atacama, in Argentina. Geologist Brian Hynek of the University of Colorado at Boulder and Argentine microbiologist María Farías conducted the research, the results of which were announced last week. The revelation was possible thanks to the study of satellite images of the region.
Discovery
Hynek and Farías examined these images for over a year and identified what appeared to be a specific network of aquifers in the middle of the desert. They decided to explore this inhospitable plateau, located at almost 4,500 meters above sea level, and there they discovered a dozen lagoons with clear, extremely saline waters, whose beds were covered by green mounds of stromatolites.
Stromatolites, known as "living rocks", are microbial reefs formed by mineral grains held together by a community of bacteria. According to NASA, they represent the oldest fossil evidence of life on our planet, dating back to at least 3.5 billion years ago. Since their origin, these organisms have obtained energy from the Sun and, by producing oxygen, they have played a crucial role in increasing this chemical element in the Earth's atmosphere to around 20%. This process allowed life to prosper on Earth.
First Records
Approximately 4.5 billion years ago, planet Earth was in the process of formation, presenting characteristics very different from those of today. During this initial phase and over many subsequent years, the continents were in the process of consolidation, resulting in intense volcanic activity. In this context, stromatolites emerged. The waters covering the Earth at the time were notably different from the waters of modern oceans, being more saline and containing significant concentrations of arsenic. In an interview with BBC World, the co-author of the discovery highlighted that during this period there was no presence of oxygen in the atmosphere, and the ozone layer, so vital for protection against solar radiation, did not yet exist.
"Under these conditions, the first forms of life emerge, which are protobacteria: bacteria that associate and form colonies", stated the microbiologist.
Throughout the colony formation process, bacteria capture carbon dioxide. According to the scientist, a part of this carbon dioxide is converted into organic matter, while the other transforms into calcium bicarbonate, thus constituting a type of living rock called stromatolites. These represent the oldest fossil records on our planet.
Similar environment
Stromatolites played a crucial role in the initial release of oxygen into the oceans and later into the atmosphere, ultimately contributing to the formation of the ozone layer. María Eugenia Farías explains that during the Cambrian period, on a planet already enriched with oxygen, there was an explosion in the diversity of eukaryotic life. Plants and animals appeared, which in turn fed on and displaced the stromatolites.
Conditions on this early planet, dating to approximately 3.5 billion years ago, are reminiscent of today's environments where stromatolites are still found, characterized by low oxygen levels, high ultraviolet radiation, volcanic activity and saline waters. Stromatolites persist in some salt lakes and bays in several parts of the world, where the reduced presence of predators allows their survival.
Australia stands out for the diversity of habitats that host stromatolites, both in their living and fossilized forms. Shark Bay, also known as Shark Bay, located in Western Australia, is notable for housing one of the largest habitats for these organisms. According to Farías, the ecosystem found in the Andes It has distinct characteristics, attributed to its location more than 3,600 meters above sea level. These conditions are similar to those that existed on Earth during the early stages of life.
What is expected for the future
Hynek and Farías plan to return to the Atacama Puna soon to continue their investigations, focusing specifically on the gypsum stromatolites. Unlike conventional stromatolites composed mainly of calcium carbonate, gypsum stromatolites form under thalasic conditions, characterized by a very high concentration of salt. These conditions are remarkably similar to those found on Mars, as highlighted by the scientist. She highlights the existence of a crater on the red planet where the water is so saline that it does not freeze.
Although we do not yet have the ability to directly explore Mars in search of signs of life, the scientist points to the Atacama Puna as a terrestrial counterpart to this peculiar Martian environment. The region offers valuable insights into possible life forms in extreme environments, providing a unique opportunity to study intense saline conditions similar to those we might find on other planets, such as Mars.
