Panspermia, translated as “seeds everywhere,” is a theory that the seeds of life are spread throughout the universe in cosmic dust or perhaps in the tails of comets, and that life on Earth began when they managed to reach the surface of the planet. The theory has origins in the ideas of Anaxagoras, a Greek philosopher, but in modern times was revived by Sir Fred Hoyle, the famous British astronomer.
There is some evidence to suggest that bacteria, the probable mechanism, or panspermia “seed” may be able to survive for very long periods of time even in deep space. Two Cal Poly scientists demonstrated back in 1995 that bacteria can survive without any metabolism for at least 25 million years, making bacteria most likely immortal. Past studies out of India, further attesting to the robustness of life, have found bacteria more than 40 km up in Earth’s atmosphere where it would be unlikely to have come from our lower atmosphere. Additionally bacteria Streptococcus mitus which was inadvertently carried to the moon on the 1967 Surveyor 3 spacecraft, was easily revived after being taken back to earth three years later.
One characteristic of panspermia would be that life in the universe would have a very similar biochemistry. So the high-altitude bacteria might be expected, whether of earth or extra-terrestrial origin, to appear very similar to terrestrial forms. This is not a testable hypothesis until life on another planet can be examined.
A major obstacle to the credibility of Panspermia theory is the fact that bacteria may not survive the tremendous heat and forces of an earth impact. No studies or evidence have been conducted or collected to confirm or deny this likelihood.
Regarding known extraterrestrial material, the “ALH84001″ rock sample believed to have come from Mars, shows some indication that microbial life may have been present at some point in the past. This widely disputed instance is the only indication we have of extraterrestrial life.
Some have taken the theory as an answer to those arguing the improbability of life spontaneously occurring on earth, that it happened elsewhere and traveled through the cosmos.
One of the newer wrinkles in the theory, purported by pranspermia.org, is that of Cosmic Ancestry.
Hoyle (and cohort Wickramasinghe) after reawakening the idea of panspermia, later broadened it to include a new understanding of evolution. They theorized that life could not have made the leaps and bounds from a single cell to humans in a mere 4 billion years; rather, the code of evolution was carried along with the seeds of life and indeed must always be so. Much in the same way the big bang set the rules for physics, life establishes the rules for its unfolding.
Parallel to their theorizing, and In the early 1970s, another man, British chemist and inventor James Lovelock proposed the theory that life controls Earth’s environment to make it suitable for itself. The theory, Gaia, as seen from a Darwinian perspective, looks suspiciously teleological. Nevertheless, the publishers of panspermia.org are calling the combination of Gaia with Hoyle and Wickramasinghe’s “strong” theory of panspermia, Cosmic Ancestry. They say that that life can only descend from life as equally evolved as itself. It also suggests that life can only come from life, requiring a supernatural being.
Now there’s a interesting combination of science, philosophy, and religion.
The straight panspermia theory has been popular in science fiction. Invasion of the Bodysnatchers by Jack Finney has been made into a feature film three times. In The Day of the Triffids, the first person narrator, writing in historical mode, takes care to reject the theory of panspermia in favor of the conclusion that Soviet biotechnology created carnivorous plants. It’s not hard to see why when you examine the fact that while interplanetary, interstellar, and perhaps even intergalactic “contamination” of life may be possible, there’s a lot of baggage associated with that simple scenario. Not the least of which is aimed at those who would use it it in lieu of spontaneous life occurring on earth as an escape mechanism. Cosmic Ancestry notwithstanding, life has to have started somewhere. Magic fairy dust hardly concludes that creationism vs. evolution debate.