Darwin was famously silent about the problem, although in a letter to his friend Joseph Hooker, Darwin confided that he imagined life originating in “some warm little pond” (see  Other Internet Resources below; and  Peretó et al. 2009). Subsequent work on the subject was sparse until the 1920s when Alexander Oparin and J.B.S. Haldane independently proposed hypotheses for life’s origin in then plausible early Earth conditions (Haldane 1929; Oparin 2010/1936). As a graduate student in the 1950s, Stanley Miller tested the proposal, discovering dozens of amino acids in the mixture (1953). Since then, the field of origins-of-life studies has expanded dramatically.