Iron-sulfur world theory
The iron-sulfur world theory is a hypothesis for the origin of life advanced by Günter Wächtershäuser involving forms of iron and sulfur. Wächtershäuser claims that an early form of metabolism predated genetics. Metabolism here means a cycle of chemical reactions that produce energy in a form that can be harnessed by other processes. The idea is that once a primitive metabolic cycle was established, it began to produce ever more complex compounds.