Dewdrop, Prebiotic Life, and Chirality

Amino acids and nucleic acids are found in meteorites and may also have formed in the early reducing atmosphere of the Earth. Such molecules may have accumulated on solid ground, for example, slopes of early volcanoes. Many kinds of molecules, for example, peptides, needed in living cells are not thermodynamically stable in aqueous solutions. This was an obvious obstacle during the early stages of prebiotic life. Clay minerals offer a possibility to overcome that problem. In combination with dewdrops, they also offer a mechanism for creating peptide chains that can copy themselves. Molecules such as amino acids and nucleic acids have chirality, that is, each molecule exists in two shapes that are each other’s mirror images, denoted as L (left) and D (right), respectively. If clay minerals were involved in early stages of prebiotic life, this offers an explanation for the homochirality found in all life on Earth. They could also provide a low-fidelity duplication mechanism before more accurate duplication mechanisms occurred on Earth.