The first reference to the word ‘Panspermia’ is in the 5 th century BCE by the Greek philosopher Anaxagoras. The theory was again revived in 1834 by scientists, specifically Jons Jacob Berzelius , then again by Lord Kevin (William Thomson) in 1871, and Svante Arrhenius in 1903. In our century, Sir Fred Hoyle and Chandra Wickramasinghe are great supporters.
Stephen Hawking also endorsed the theory.
But what is the Panspermia Theory? Panspermia is a Greek word which means ‘seeds everywhere’. The Panspermia theory presents the hypothesis that the ‘seeds’ responsible for life on Earth exist everywhere in the Universe and propagate to different planets throughout space and give life. Therefore, the belief is that life on Earth also originates from those universal ‘seeds’.
Lord Kelvin said in 1871:
"[W]e must regard it as probable in the highest degree that there are countless seed-bearing meteoric stones moving about through space. If at the present instance no life existed upon this Earth, one such stone falling upon it might, by what we blindly call natural causes, lead to its becoming covered with vegetation."
There are three different variations of the panspermia hypothesis:
- Lithopanspermia – A variation of panspermia which explains that life can be transferred from one solar system to another inside rocks (like meteorites). This variation had the support of Lord Kelvin and Hermann von Helmholtz.
- Ballistic panspermia – A variation in which rocks expelled by planets within an individual solar system can transfer biological material from one planet to another. Max K. Wallis and N.C. Wickramasinghe supported this idea in their publication "Role of Major Terrestrial Cratering Events in Dispersing Life in the Solar System," (Earth and Planetary Science Letters, 1995)
- Directed panspermia – Refers to the deliberate spreading of microorganisms in space, which suggest that an advanced extra-terrestrial civilization is intentionally spreading the universal ‘seeds’ of life to other planets to propagate, or create life. The first to allude to this idea were Shklovskii and Carl Sagan in 1966.
Each variation does not necessarily conflict with the others, since all of them could take place in different parts of the universe.
Stronger evidence to support the Panspermia hypothesis appeared on May 11, 2001, when Geologist Bruno D'Argenio and the molecular biologist Giuseppe Geraci, both from the University of Naples , discovered bacteria in a meteorite that was over 4.5 billion years old. The spores had found shelter in the crystal structure of minerals that were present in the formation. The two scientists claimed that they had managed to resurrect the spores after using a medium of alcohol at very high temperatures. The most interesting thing about the discovery was that the DNA of the bacteria—though of a different strain—appears to be related to modern day Bacillus subtilis and Bacillus pumilus . This proves that strains of DNA found on Earth can also be found elsewhere in the universe.
By John Black