Precambrian Stromatolites from Siyeh Formation, Glacier National Park, Montana, USA
Abiogenesis is the process by which living matter arose from nonliving matter, which is hypothesized to have occurred around 4 billion years ago. Some scientists suggest that this process occurred after amino acids fell from space, as amino acids have been detected in nebulae, and formed the four ribonucleic acid (RNA) nucleotides--adenine, cytosine, guanine, and uracil. The wet-dry cycles on the coast and in small pools could have been a catalyst for the necessary reactions. These nucleotides formed RNA, which replicates without enzymes, but the RNA would likely have been too vulnerable to survive in the hot, churning oceans; thus, it must have had some sort of protection. That protection could have been a micelle, a mono-layered phospholipid bubble (phospholipids naturally form bubbles when in water), and allowed the RNA to safely replicate and evolve. Over time the RNA would have likely evolved into deoxyribonucleic acid, and the simple micelle would likely have evolved into the more complex liposome and then phospholipid bi-layer.