A team of researchers from Japan have taken a look back in time to Hadean Earth, when our planet was only a few hundred million years old, to help explain how a crucial ingredient for life may have first formed.
From lunar crater records, scientists predict that early Earth’s oceans were bombarded with meteorites and asteroids. These intense impacts likely triggered a reaction between the space rocks, water, and the surrounding atmosphere. Using a meteorite analogue (that included iron), oceanic components, and molecules believed to have been abundant in the atmosphere over 4 billion years ago (namely carbon dioxide and nitrogen), researchers investigated the products of such an event.
As described in their paper, published in Nature’s Scientific Reports, amino acids, such as glycine and alanine, were formed in the team’s simulations. Chains of amino acids make up proteins, biomolecules essential for life as they catalyze (speed up) many biological reactions. Therefore, the team believe they have demonstrated the role of meteorites in helping to spark life on Earth.
Although amino acids have been created previously in other simulations of events on primitive Earth, the majority have relied on the presence of compounds such as ammonia and methane, less significant components of the early atmosphere. So, for the latest experiment, the team wanted to instead test whether in an atmosphere of carbon dioxide (CO2) and nitrogen (N2) – the most abundant sources of carbon and nitrogen at the time – amino acids would still arise.
“Making organic molecules form reduced compounds like methane and ammonia are not difficult, but they are regarded as minor components in the atmosphere at that time," corresponding author Yoshihiro Furukawa from Tohoku University, Japan, said in a statement. “The finding of amino acid formation from carbon dioxide and molecular nitrogen demonstrates the importance in making life's building blocks from these ubiquitous compounds.”
The team’s discovery could also have implications for life on other planets. At a similar time to Hadean Earth, Mars was thought to have had large lakes or oceans (the Noachian period) and an atmosphere dominated by carbon dioxide and nitrogen. This raises the possibility of impact-induced amino acid formation on the Red Planet that may also have led to the production of more advanced ingredients of life.
“Further investigations will reveal more about the role meteorites played in bringing more complex biomolecules to Earth and Mars,” Furukawa stated.
