An asteroid impact 78 million years ago has been called the cradle of life on Earth.
Life blossomed 4.4 million years after an asteroid struck Earth.
For the first time, scientists have pinpointed the precise time of life's origin in an impact crater: microbial colonization of the hydrothermal system beneath the Finnish crater Lappajärvi began 4.4 million years after the asteroid impact 78 million years ago.
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Scientists have discovered that 78 million years ago, an asteroid 1.6 kilometers in diameter struck what is now Finland, forming the Lappajärvi crater, 23 kilometers wide and 750 meters deep. The catastrophic impact created a complex network of cracks in the rock that filled with hot water, forming a unique hydrothermal system. Scientists have long suspected that such conditions could have been ideal for the origin of life, but only now has an international research team been able to find irrefutable evidence and precisely date the moment when microbes colonized the crater.
The study used advanced isotope analysis and radioisotope dating techniques. Scientists discovered pyrite with an abnormally high content of the sulfur-34 isotope in the crater's mineral deposits—an unmistakable sign of microbial activity that converts sulfates into hydrogen sulfide in anoxic conditions. This process, known as anaerobic respiration, is fundamental to the global sulfur and carbon cycle on Earth.
The most striking discovery is the precise dating of the onset of life in the crater. The first mineral deposits, formed at temperatures suitable for life (47 degrees Celsius), appeared 4.4 million years after the impact—73.6 million years ago.
"This is the first time we can directly link microbial activity to a meteorite impact using geochronological methods," emphasizes researcher Henrik Drake.
Over the following millions of years, microbial life only strengthened its position. As the crater gradually cooled, calcite with characteristic biogenic signatures formed in the rock cavities—further evidence of the long-term thriving of microorganisms in this unique ecosystem. As scientist Gordon Osinski notes, this study is the first to definitively link the crater's colonization to the aftermath of the impact, rather than to later geological processes.
The discovery has far-reaching implications for astrobiology. Impact craters may not only be sources of organic compounds (asteroids contain amino acids and other "building blocks of life") but also ready-made shelters for its development. This is especially relevant for Mars, where numerous craters could have created similar hydrothermal systems. The methods developed by the authors could be applied to the analysis of samples from the Red Planet planned for return to Earth in future missions.
The study also demonstrates the remarkable resilience of life: even after catastrophic events capable of destroying the biosphere, nature finds ways to regenerate in the most unexpected places. The authors conclude that medium- and large-scale impact craters can create long-lived hydrothermal systems that become oases of life as they cool—an effect that is crucial for understanding the origins of life on Earth and beyond.
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