In the natural sciences, abiogenesis, the question of the origin of life, is the study of how life on Earth might have emerged from non-life. Scientific consensus is that abiogenesis occurred sometime between 4.4 billion years ago, when water vapor first liquefied, and 2.7 billion years ago, when the ratio of stable isotopes of carbon ( 12 C and 13 C ), iron and sulfur points to a biogenic origin of minerals and sediments and molecular biomarkers indicate photosynthesis. This topic also includes panspermia and other exogenic theories regarding possible extra-planetary or extraterrestrial origins of life, thought to have possibly occurred sometime over the last 13.7 billion years in the evolution of the Universe since the Big Bang.

Origin of life studies is a limited field of research despite its profound impact on biology and human understanding of the natural world. Progress in this field is generally slow and sporadic, though it still draws the attention of many due to the eminence of the question being investigated. Several theories have been proposed, most notably the iron-sulfur world theory (metabolism first) and the RNA world hypothesis (genetics first).