Origin of life
The origin of life may refer to either of the following
- the event in which life first emerged from nonliving substances: Terran abiogenesis
- the event in which life first appeared on Earth: Terran genesis
The best evidence so far seems to indicate that both of these were in fact the same event, but there is still some possibility that life arose elsewhere and later spread to Earth; this is known as the panspermia theory.
- The origin of species is the means by which different species came to exist; this is also sometimes inaccurately referred to as the "origin of life".
- The general name for the process by which life can emerge from nonliving substances, wherever and whenever it may occur (i.e. not just on Earth and not necessarily our tree of life), is abiogenesis.
- The means by which more complex forms can derive from simpler ones is called evolution; the evidence-based explanation for the emergence of present-day species from the first organisms on Earth is evolution by natural selection.
- The question of how life was created is one of several key "creation" questions which form the core of many mythologies and for which science has begun to provide likely answers only fairly recently.