A 3.26 billion-year-old meteorite may triggered early life’s evolution

A meteorite that struck Earth 3.26 billion years ago, far larger than the one that contributed to the dinosaurs’ extinction, caused extensive destruction but may have positively influenced the early development of life. Researchers suggest this colossal impact acted as “a giant fertilizer bomb,” enriching the environment with essential nutrients like phosphorus and iron, which benefitted bacteria and archaea that dominated the planet at the time.

To study the effects of this ancient impact, scientists analyzed geological evidence from the Barberton Greenstone Belt in northeastern South Africa. They discovered significant indicators, including the geochemical signatures of preserved organic material and fossils of marine bacteria mats, suggesting that life not only recovered rapidly after the disaster but also thrived.

“Life not only rebounded quickly once conditions normalized, but it actually flourished,” said Nadja Drabon, a Harvard University geologist and lead author of the study published in the Proceedings of the National Academy of Sciences.

During the Paleoarchean Era, when this event occurred, Earth was vastly different, resembling a water world with few volcanoes and little land. The atmosphere was devoid of oxygen, and cellular life with nuclei did not yet exist.

The meteorite, classified as a carbonaceous chondrite, was approximately 23 to 36 miles (37 to 58 km) wide—50 to 200 times the size of the asteroid that caused the extinction of the dinosaurs. The impact released immense energy, vaporizing the rock and sediment it struck, resulting in a cloud of vapor and dust that darkened the sky almost instantly.

The collision likely occurred in the ocean, generating a massive tsunami that disturbed the sea floor and inundated coastlines. The immense heat from the impact would have caused the upper layers of the oceans to boil. It could take years for the dust to settle and for the atmosphere to cool enough for water vapor to return to the oceans, decimating sunlight-dependent microbes in shallow waters.

However, the meteorite delivered significant amounts of phosphorus—crucial for the creation of molecules responsible for storing and transmitting genetic information. The tsunami also mixed iron-rich deep waters with shallower areas, fostering conditions favorable for many microbial life forms, as iron serves as a vital energy source.

“Think of these impacts as giant fertilizer bombs,” Drabon remarked. While meteorite strikes are often viewed as catastrophic events—like the Chicxulub impact that wiped out the dinosaurs—3.2 billion years ago, life was simpler and more adaptable.

Microorganisms are uncomplicated and reproduce rapidly, making them more resilient to environmental changes. Evidence of the impact includes chemical signatures from the meteorite, small spherical formations resulting from the melted rock, and sedimentary rock containing seabed debris stirred up by the tsunami.
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