Our ancestors in caves spent countless hours sharpening and smashing rocks together. Eventually, the right combination of stone, spark and sun-dried leaves came together to create flame, an invention that would quickly catapult our species into the tippy-top of the
Earth’s food chain. What if we told you that a similar, albeit exponentially more massive, smashing of rocks billions of years ago could have set the stage for
life on Earth?
According to a recent study,a
meteorite the size of four Mount Everests slammed into our planet 3.26 billion years ago. To say this impact was colossal is an understatement. Scientists now believe that the event, dubbed the "
S2 impact," caused a massive chain reaction that may have helped shape life as we know it.
When this meteorite hit, it likely triggered a tsunami so powerful it tore through shallow waters, dragging sediment and debris into the oceans. The researchers explained that the impact was so intense that the top layers of the ocean boiled off, and a thick blanket of dust darkened the skies, cutting off sunlight for photosynthesis.
Now, this might sound like a doomsday scenario, but for the microscopic organisms living back then, it was an opportunity. According to Nadja Drabon, a geologist at Harvard who led the study, "We think of impact events as being disastrous for life. But what this study is highlighting is that these impacts would have had benefits to life, especially early on."
Life in the wake of destruction
So how exactly did life survive — and even thrive — after such a
cataclysmic event?
The answer lies in two elements:
iron and phosphorus. The giant tsunami stirred up iron from the depths of the ocean, while phosphorus was delivered to Earth by the meteorite and increased erosion. Both elements are essential for life, and in the aftermath of the S2 impact, bacteria that could metabolise iron likely had a field day.
Drabon's team found evidence that bacteria quickly bounced back after the meteorite hit, and their populations surged. These iron-loving
microorganisms might have found their perfect environment in the chaotic post-impact world. "What this study is showing is that these impacts might have actually allowed life to flourish," Dragon explains.
The clues to this ancient event are hidden in the
Barberton Greenstone Belt in South Africa. This region, one of the oldest geological formations on Earth, contains layers of rock that preserve evidence of past meteorite impacts, including the S2 event. By painstakingly examining these rocks, Drabon and her team have pieced together a picture of the world as it was billions of years ago.
Not a one time event
Their research involves collecting rock samples just centimetres apart and analysing them for chemical signatures that hint at ancient tsunamis, changes in ocean chemistry, and the rise of
early bacterial life — essentially solving a 3-billion-year-old mystery, one thin slice of rock at a time.
From this, the researchers also deciphered that this wasn't just a one-time event. The Barberton Greenstone Belt contains evidence of at least eight major meteorite impacts, suggesting that Earth was regularly bombarded by space rocks during its early years. Each impact may have played a role in shaping the course of life on our planet.
Drabon and her team plan to continue exploring the Barberton region, hoping to uncover more details about these
ancient impacts and how they influenced Earth's early ecosystems. The more we learn about these dramatic events, the clearer it becomes that, while destructive, they were also key drivers of change.
The findings of this study have been published in the
Proceedings of the National Academy of Sciences and can be accessed
here.
