Panspermia

Panspermia is the hypothesis that the seeds of life are prevalent throughout the universe, and furthermore that life on Earth began by such seeds landing on Earth and propagating themselves. The idea has its origins in the writings of Anaxagoras, but was first proposed in its modern form by Hermann von Helmholtz in 1879. Panspermia can be said to be either interstellar (between star systems) or interplanetary (between planets in the same solar system). There is as yet no compelling evidence to support or contradict it, although the consensus view holds that panspermia?especially in its interstellar form?is unlikely given the challenges of survival and transport in space.

Directed Panspermia

A second prominent proponent of panspermia is Nobel prize winner Francis Crick, who along with Leslie Orgel proposed the theory of directed panspermia in 1973. This suggests that the seeds of life may have been purposely spread by an advanced extraterrestrial civilization. Crick argues that small grains containing DNA, or the building blocks of life, fired randomly in all directions is the best, most cost effective strategy for seeding life on a compatible planet at some time in the future. The strategy might have been pursued by a civilization facing catastrophic annihilation, or hoping to terraform planets for later colonization.

Related Topics:
Francis Crick - Leslie Orgel - Terraform

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Other proponents of panspermia believe that life never evolved from inorganic molecules, but that it has existed as long as all other forms of matter. This is an extension of panspermia called cosmic ancestry.

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