If you traveled back in time 4 billion years ago, you would surely be surprised by what you would see around you because, instead of peaceful blue skies and an oxygen-rich atmosphere, the Earth would be covered in a haze of noxious gases, seas of lava and an endless avalanche of asteroid and meteor impacts. It is the Hadean Land , a geological age named after Hades, the Greek god of the underworld, and also the Hebrew word for hell. Right now, there is no life form on the planet, not even tiny microscopic bacteria.
The origin of life is perhaps the most debated and headache-ridden existential question that has given scientists and philosophers for centuries. Today, the consensus states that the appearance of amino acids comes from the extraterrestrial supply through meteorites.
How to find out?
Researchers from Tohoku University, the National Institute of Materials Science (NIMS), the Center for Advanced Research in High Pressure Science and Technology (HPSTAR), and Osaka University took a look back in time at the Land of the Andes, using a computer simulation of a meteorite crashing into the ocean, when our planet was only a few hundred million years old , to help explain how a crucial ingredient for life was formed.
Based on records from the lunar crater, scientists predict that Earth’s first oceans were bombarded with meteorites and asteroids. These intense collisions likely triggered a reaction between space rocks, water, and the surrounding atmosphere . Using a meteorite analog (which included iron), oceanic constituents, and molecules believed to be abundant in the atmosphere more than 4 billion years ago (namely carbon dioxide and nitrogen), the researchers examined the products of such an event. . Amino acids were formed, such as glycine and alanine; chains of amino acids form proteins, biomolecules essential for life, since they catalyze (accelerate) many biological reactions. Therefore, experts believe that they have demonstrated the role of meteorites in helping the awakening of life on Earth.
In summary, the study uncovered the emergence of amino acids that serve as building blocks for proteins, demonstrating the role of meteorites in bringing the molecules of life to Earth and, potentially, to Mars.
“Making organic molecules form reduced compounds like methane and ammonia is not difficult, but they are considered minor components in the atmosphere at the time,” says Yoshihiro Furukawa, a researcher at Tohoku University and leader of the study that publishes the journal. Scientific Reports. “The finding of the formation of amino acids from carbon dioxide and molecular nitrogen demonstrates the importance of creating the building blocks of life from these ubiquitous compounds.”
The team’s discovery could also have implications for life on other planets.
It is very likely that carbon dioxide and nitrogen were also the main constituent gases of the ancient atmosphere of Mars. Recall that until 2,000 million years ago, Mars was home to oceans of liquid water and an atmosphere dominated by carbon dioxide and nitrogen; it may have been very similar to Earth. If Mars ever harbored life, the same essential building blocks may have been seeded in a similar way as it might have happened on Earth; at least, this research shows that such a scenario is plausible.
“Further research will reveal more about the role meteorites played in bringing more complex biomolecules to Earth and Mars,” said Furukawa.
Referencia: Yuto Takeuchi et al. Impact-induced amino acid formation on Hadean Earth and Noachian Mars, Scientific Reports (2020). DOI: 10.1038/s41598-020-66112-8, www.nature.com/articles/s41598-020-66112-8
