Asteroid impacts: The unlikely cradle of early Earth life
New geological research suggests that the gigantic asteroid impact over 3 billion years ago, despite creating extreme conditions on our planet, may have provided a conducive environment for the flourishing of early bacterial life forms.
24 October 2024 18:01
Harvard University scientists, led by geologist Nadja Drabon, analyzed rocks from the Barberton Greenstone Belt in South Africa to reconstruct events from 3.26 billion years ago. Geological evidence points to an asteroid impact known as S2, estimated to be up to 200 times larger than the object that led to the extinction of the dinosaurs.
The powerful collision triggered a tsunami, mixing ocean waters and transferring dust from land to coastal areas. The heat generated by the impact caused the surface layers of the oceans to boil and the atmosphere to heat up. A dense dust cloud rose, blocking sunlight and hindering photosynthesis.
The first traces of bacterial life on Earth: It didn't last long
Despite these drastic changes, bacterial life not only survived but quickly rebounded. According to Drabon's team's analyses, there was a rapid increase in populations of unicellular organisms utilising iron and phosphorus. Iron was likely moved from the ocean depths to shallower areas, and phosphorus came from both the meteorite and increased land erosion.
This short-term ecosystem shift towards iron-using bacteria is an important element in understanding the beginnings of life on our planet.
Research conducted in the Barberton Greenstone Belt, on the eastern edge of the Kaapvaal craton considered to be the Earth's original crust from 3.5 to 2.5 billion years ago, revealed evidence of at least eight similar meteorite impacts. The results were published in the journal "Proceedings of the National Academy of Sciences," and scientists plan to continue their work to further explore the impact of these ancient events on the evolution of life on Earth.
