The most recurrent explanation the
phenomenon of life earth is the
mythological. from various parts
of world developed explanatory
myths the origin of animals
human beings. Some of myths
were incorporated into and
almost all religions metaphorical or
transcendental explanations the
origin of life the planet.

With the of science new
explanatory shave emerged.
Notable among are the
spontaneous generation , or
abiogenesis, that asserted living
beings were created nonliving
material, the cosmic
hypothesis, theory that life earth is a
result seeding from the outer ,
the autotrophic hypothesis, according
which the first living were
autotrophs, and the
hypothesis,the most accepted
nowadays, affirms that life
emerged heterotrophic cells.

At the of the 1980s decade new
hypothesis known as RNA world
hypothesis was . This
hypothesis asserts that life
had only RNA genetic material and as
molecules that later turned
DNA and proteins. The world
hypothesisis strengthened by fact
that RNA can a catalytic role, like
, and by the finding some
bacteria have ribosomes only of
RNA without proteins.