A study has suggested that about 3.26 billion years ago, a celestial object the size of four Mount Everests collided with Earth, triggering the evolution of life. The image is provided by NASA.
Billions of years ago, before the emergence of life on Earth, celestial objects such as asteroids, meteors, and comets frequently collided with the planet. It is generally accepted that the extinction of the dinosaurs at the end of the Cretaceous period was caused by the impact of an asteroid about 10 kilometers in diameter. Recently, research has indicated that about 3.26 billion years ago, an asteroid the size of four Mount Everests collided with Earth, drastically altering the planet’s environment.
A joint research team from Harvard University, Stanford University’s departments of Earth and Planetary Sciences and Oceanography, and ETH Zurich’s Department of Earth Sciences revealed that a celestial body named ‘S2’ collided with Earth, which at the time hosted only single-celled bacteria and archaea, spurring the evolution of life. The findings were published in the October 22 issue of the international journal ‘PNAS’ by the National Academy of Sciences in the United States.
The research team collected rock samples at centimeter intervals from the Barberton Greenstone Belt in South Africa, known to be the largest terrestrial meteorite impact zone, after the massive meteor the size of four Mount Everests struck the area. They conducted analyses involving sedimentology, geochemistry, and carbon isotope compositions. The impact of the S2 collision was reportedly up to 200 times larger than the asteroid that caused the extinction of the dinosaurs. It traveled at speeds of 20 kilometers per second, releasing an immense amount of energy, causing tsunamis thousands of meters high, and inducing a magnitude 10.8 earthquake across the globe. The collision generated heat that boiled the sea surface and heated the atmosphere, creating thick dust clouds that halted photosynthesis, according to scientists.
The analysis revealed that bacteria quickly recovered post-impact, with a rapid increase in single-celled organisms feeding on phosphorus (P) and iron (Fe). Iron was swept from the deep ocean to shallower waters due to the tsunami, phosphorus was delivered directly by space objects, and it also increased due to weathering and erosion on land. According to the research team, iron-metabolizing bacteria thrived briefly after the collision, providing a crucial piece of the puzzle for understanding early life’s proliferation.
Leading the research, Professor Nadja Drabon from Harvard University stated, “The Barberton Greenstone Belt contains evidence of at least eight celestial impact events, including S2.” She added, “While impacts like S2 led to mass extinctions, they also provided positive aspects for life on another front.” Drabon further explained that celestial impacts likely accelerated the emergence of the first ocean, the appearance of continents, plate tectonics, and the evolution of life, suggesting they enabled early life forms to thrive.