Ancient cataclysm may have jump-started Earth's early life
The impact of a meteorite, 200 times larger than the one that led to the extinction of the dinosaurs, could have contributed to the development of life on our planet, say scientists who explain the reasons behind this.
24 October 2024 16:36
Billions of years ago, before life forms similar to today's appeared on Earth, meteorites regularly bombarded our planet. One such impact occurred 3.26 billion years ago, and geological evidence of this event has been found in rocks in South Africa.
Nadja Drabon, a geologist from the Department of Earth and Planetary Sciences at Harvard University, and her team collected and analyzed rocks, studying their sedimentology, geochemistry, and carbon isotopic composition. The results of this research have been published, revealing the alleged sequence of events from over 3 billion years ago when an asteroid struck Earth.
S2 and life on Earth
This historical event, known as S2, is estimated to have been significantly larger than the object responsible for the extinction of the dinosaurs—up to 200 times larger. The S2 impact triggered a tsunami that mixed ocean waters and swept dust from the lands into coastal areas.
The heat generated by the impact was also significant, boiling the surface of the ocean and increasing atmospheric temperature. A thick layer of dust covered the planet, preventing photosynthesis.
Despite this, bacteria quickly rebuilt their populations. The number of organisms feeding on phosphorus and iron also rapidly increased. Iron could have been brought up from ocean depths, and phosphorus came from both meteorites and increased land erosion.
Tragedy contributed to development
Analyses conducted by Drabon indicate that bacteria with iron-based metabolism quickly thrived, a direct effect of the impact. Although short-lived, this shift towards life forms that favoured iron may have had a crucial impact on the early stages of life's development on Earth.
"We think of impacts as catastrophic for life. But this study shows that they also provided benefits to life, especially in its early stages, potentially allowing it to flourish," says Drabon.
The research was conducted in the Barberton Greenstone Belt, a geological formation located on the eastern edge of the Kaapvaal Craton in South Africa. This area is considered part of the Earth's primordial crust from 3.5 to 2.5 billion years ago. In addition to the S2 impact, evidence of at least eight other meteorite impacts has been discovered. Scientists intend to continue researching these issues.
