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How could a major impact change the course of biological evolution?

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four impact craters — Meteorite crater Four impact craters of the same size (30 km [20 miles] in diameter) imaged by spacecraft on different solid bodies of the solar system and reproduced at the same scale. They are (clockwise from upper left) Golubkhina crater on Venus, Kepler crater on the Moon, an unnamed crater on Jupiter's moon Ganymede, and an unnamed crater on Mars. The images are oriented such that the craters appear illuminated from the left; the Venusian crater is imaged in radar wavelengths, the others in visible light.

A major impact can fundamentally alter the course of biological evolution by triggering mass extinction events, which clear existing ecological niches and create opportunities for surviving species to diversify and thrive.1

Large impacts, such as the one that created the Chicxulub crater, cause catastrophic environmental shifts. These events can release massive amounts of dust and particles into the atmosphere, blocking sunlight for years and halting photosynthesis. This collapse of the food chain leads to widespread species loss, such as the demise of the dinosaurs at the end of the Cretaceous Period.234

By removing dominant groups, these events fundamentally shift the trajectory of life. For instance, the extinction of large reptiles allowed mammals to rise as the dominant land animals, eventually leading to the emergence of the human species. Furthermore, in the early history of the solar system, such impacts may have repeatedly wiped out early life, potentially forcing it to establish a foothold in protected environments like the deep ocean or Earth's crust.2