User:Eseymour/Origin of life
The origin of life refers to the first appearance of living organisms on Earth. The question of how life came to exist on Earth has been a subject of considerable interest since the beginning of human civilization. Answers to this question have been proposed through religion, philosophy, and science. Although there is no universally accepted explanation for the origin of life, there are several widely-held concepts. Not all are mutually exclusive.
Concepts
[edit]Abiogenesis
[edit]Abiogenesis is the idea that non-living chemicals self-assembled into living organisms by natural processes. Several hypotheses for abiogenesis have been proposed, most notably the iron-sulfur world theory, which hypothesizes that a primitive metabolism emerged first, and provided an environment for the emergence of RNA replication, and the RNA world hypothesis, which suggests that relatively short RNA molecules spontaneously formed that were capable of catalyzing their own replication.
Panspermia
[edit]Panspermia is the hypothesis that "seeds" of life exist all over the Universe, and that Earth life originated from such seeds. The closely-related concept of directed panspermia suggests that rather than being spread throughout the universe, an advanced extraterrestrial civilization purposely sent seeds of life to Earth.
Creation
[edit]Creation is the idea that a deity created life. This concept is an element of many religions, although many who hold this concept do not adhere to any particular religion.
