Evolution does not attempt to explain the origin of life or the origin and development of the universe. While biological evolution describes the process by which species and other levels of biological organization originate, and ultimately leads all life forms back to a universal common ancestor, it is not primarily concerned with the origin of life itself, and does not pertain at all to the origin and evolution of the universe and its components. The theory of evolution deals primarily with changes in successive generations over time after life has already originated.

There is still no "standard model" of the origin of life. Most currently accepted models draw at least some elements from the framework laid out by the Oparin-Haldane hypothesis. Under that umbrella, however, are a wide array of disparate discoveries and conjectures.

An alternative to Earthly abiogenesis is the hypothesis that primitive life may have originally formed extraterrestrially (Extraterrestrial life), either in space, on Mars or elsewhere. A supporter of this theory was Francis Crick. Also related, NIH scientists reported studies, based on extrapolating "genetic complexity of organisms to earlier times", suggesting life began "9.7 ± 2.5 billion years ago", billions of years before the Earth was formed. The scientists noted that Life may have started "from systems with single heritable elements that are functionally equivalent to a nucleotide"

Organic compounds are relatively common in space, especially in the outer solar system where volatiles are not evaporated by solar heating. Comets are encrusted by outer layers of dark material, thought to be a tar-like substance composed of complex organic material formed from simple carbon compounds after reactions initiated mostly by irradiation by ultraviolet light. It is supposed that a rain of material from comets could have brought significant quantities of such complex organic molecules to Earth.