Biomolecule formation by oceanic impacts on early Earth

Abstract

Impacts of extraterrestrial objects were frequent on the early Earth. Shock experiments suggest that the impact of the most common type of meteorites into sea water could have synthesized the organic molecules that served as the building blocks of life. Intense impacts of extraterrestrial objects melted the embryonic Earth, forming an inorganic body with a carbon-dioxide- and nitrogen-rich atmosphere1,2. Certain simple organic molecules have been shown to form under conditions resembling meteorite impacts, although the link between these events and the development of more complex molecules remains unclear3. Ordinary chondrites, the most common type of meteorite, contain solid carbon, iron and nickel—elements essential to the formation of organic chemicals4,5. Here we use shock experiments to recreate the conditions surrounding the impact of chondritic meteorites into an early ocean. We used a propellant gun to create a high-velocity impact into a mixture of solid carbon, iron, nickel, water and nitrogen. After the impact, we recovered numerous organic molecules, including fatty acids, amines and an amino acid. We suggest that organic molecules on the early Earth may have arisen from such impact syntheses. As the natural impacts that were frequent on the early Earth are more sustained and reach higher pressures than our experiments6,7, they may have resulted in the synthesis of a greater abundance, variety and complexity of organic compounds.