When it comes to life and its history on Earth, meteorite impacts have been one of the ever-present threats to total extinction. It's even possible that life may have had multiple beginnings — with early iterations being utterly destroyed by the impact of a massive body early in Earth's history.
We know, though, that life has managed to expand and diversify into almost every available ecological niche on the planet and that all life on Earth can be traced back to a last universal common ancestor that existed some 3.6 billion years to 4.2 billion years ago. Since then, impacts on Earth's surface have regularly disrupted the living order, yet life remains.
Meteorite impacts, when viewed through their ability to radically alter Earth's environment, have been considered a force for destruction. However, with a more nuanced perspective on the history of life on Earth, along with a greater understanding of the role that meteorite impacts have had in shaping the world we live in, scientists are reconsidering these events as detrimental to a planet's ability to support life.
How Meteorites Shaped Earth's Evolution
Alexandra Pontefract, a microbiologist who specializes in how impacts influence planetary habitability from Johns Hopkins' Applied Physics Laboratory, thinks that the sentiment that impacts are detrimental to life can be traced back to our understanding that the mass extinction of the dinosaurs was due to a large impact at the end of the Cretaceous.
