The most striking illustration of the destructive power of space rocks on Earth is the asteroid that wiped out the dinosaurs and about three-quarters of all plant and animal species about 66 million years ago.

However, scientists recently discovered evidence of an even older and larger meteorite that struck Earth – one that may actually have helped life thrive rather than destroying it. This impact occurred about 3.3 billion years ago, during the early years of the solar system, when asteroid collisions were much more common.

This meteorite, designated S2, is approximately 200 times larger than the Chicxulub responsible for the extinction of the dinosaurs. When S2 hit Earth, off the coast of Cape Cod, only single-celled organisms were present. The impact boiled the oceans, caused global darkness and triggered tsunamis that tore apart coastal seabeds.

However, the devastation may have led to a significant increase in bacterial and archaeal populations.

Harvard geologist Nadja Drabon and her team discovered evidence of this ancient impact in South Africa’s Barberton greenstone belt. They painstakingly collected rock samples, analyzed their chemical compositions, and studied the distribution of various carbon isotopes, allowing them to reconstruct the events surrounding the S2 impact.

“We often think of impact events as catastrophic to life,” said Drabon, the team leader. “This study suggests that such impacts may actually have facilitated the expansion of life, particularly in its early stages.”

Their research was published Oct. 21 in the “Proceedings of the National Academy of Sciences.”

When S2 collided with Earth, it would have generated a massive tsunami that would have disrupted the ocean floor and flooded coastal areas with debris. The extreme heat from the impact would have boiled the upper layers of the ocean and warmed the atmosphere.

The impact would have thrown debris into the atmosphere, creating a thick cloud of dust blocking sunlight, thereby hindering the photosynthesis of many simple organisms. However, some bacteria managed to survive and recover quickly. Researchers believe that single-celled organisms that consumed iron and phosphorus thrived following this catastrophic event.

Population spikes in some single-celled strains were likely due to iron dredged from the depths of the ocean and transported to shallower waters by the tsunami. An influx of phosphorus would have occurred as the land eroded and additional phosphorus would have been introduced by the impact itself, the researchers said.

The researchers hypothesize that iron-consuming bacteria initially developed after the S2 impact, albeit briefly. This shift toward iron-metabolizing bacteria adds to our understanding of the early evolution of life on Earth.

This discovery marks the eighth asteroid impact identified in the area studied by Drabon and his team. Their discoveries were made possible through intensive field work, scouring mountain passes for sedimentary evidence of ancient impacts that has been preserved over time.

The team plans to continue exploring the region for other signs of asteroid impacts, tsunamis and other cataclysmic events that could shed light on Earth’s history.