The panspermia, Also called the cosmic origin theory or extraterrestrial theory of life, it is one of the theories proposed to explain the origin of life on planet Earth. It is based, fundamentally, on the fact that life on this planet arose from "life-bearing seeds" from outer space..
The term "panspermia" derives from the Greek words bread, which means "everything", and sperm, which means "seed", so it is usually translated as seeds everywhere or seeds everywhere. This expression is used to refer to the existence of vital "seeds" or "nuclei" traveling through outer space that could have reached the Earth and have given rise, by evolution, to life as we know it today..
At present, although this is not the most accepted By the scientific community, some authors still consider that it may be a valid scientific hypothesis, although difficult to prove, and it is for this reason that there are more and more people interested in the field of astrobiology.
Article index
In the literature there are some discrepancies regarding the first philosophical notions of the theory of panspermia: some authors establish that the first to coin the term was the Greek philosopher Anaxagoras, while others propose that it was Aristarchus of Samos, several centuries later..
Whatever the correct story, it is important to verify that, although it is considered a theory born at the beginning of the 20th century, the conceptualization of the possibility that life traveled between different planets in the form of seeds saw the light many centuries before Christ.
Beyond the philosophical point of view, the theory of panspermia emerged shortly after the French bacteriologist Louis Pasteur completely discredited the theories related to the origin of life by spontaneous generation, in the late 19th century.
Initially, the conception of panspermia had the support of different recognized scientists during some years of the 19th century. However, the real responsible for its promotion was the Swedish chemist Svante Arrhenius, who in the early 1900s suggested that microscopic spores may have been transported through interplanetary space thanks to radiation pressures from the sun..
Some of the thinkers of the time who supported these ideas used the works of Charles Darwin on the origin and evolution of species as essential foundations to explain the possibility that, thanks to evolution, "simple" life forms could be exchanged between planets and develop in more "advanced" ways.
Essentially, the theory of panspermia proposes that life did not form on Earth, but began on this planet thanks to the “germination” of some “life-bearing seeds” that came from somewhere in space propelled by some type of force.
In a way, panspermia proposes that all living beings on Earth and, if any, on other planets or in the rest of the Universe, are related in a certain way. Therefore, it throws the possibility that life has always existed, that is, it is eternal.
Different authors agree on the approach to panspermia as a process comprised of three different phases:
Born in Sweden in 1779, Berzelius was an important chemist, recognized not only for his contributions in the discovery of different elements, but also for his declared convictions panspermists.
Around 1830, this Swedish scientist established that in space there were different celestial bodies that contained carbon (organic) compounds conducive to the emergence of living beings.
He is considered one of the pioneers in making scientific statements that will support the notions about the extraterrestrial origin of life.
Born in Ireland in 1824 and died in Scotland in 1907, this British mathematician and physicist is described in some texts as one of the pioneers in the first serious scientific statements regarding the ideas of the origin of life by panspermia.
Specifically, his speech to the British Association, in 1881, evidenced his strong convictions regarding the existence of countless space stones and meteorites laden with "life-bearing seeds" moving through space. He raised the possibility that one of those rocks fell on the earth due to natural causes and covered it with vegetation..
This doctor and physicist, born in Germany in 1821, was another important sympathizer of the theories panspermists. He is known for his contributions to ideas about the origin of planetary systems and for his ideas about the presence of carbon compounds in meteorites, of life traveling in these meteorites and the insemination of our planet with them..
This famous British naturalist, who lived between 1809 and 1882, was the author of the still acclaimed work on the origin, evolution and adaptation of species: The origin of species, published in 1859.
Although in his publications he never made reference to specific ideas about the origin of life on Earth - much less panspermia - different historians of science consider that the publication of his works gave shape and support to the thoughts of the philosophers and scientists of the time who supported the theory of panspermia.
Unconsciously, Darwin's proposals on the evolution and adaptation of species made the ideas panspermists were supported by the possibility of progression from extremely simple life forms to the more complex forms that characterize current animals and plants, for example.
This Swedish scientist, born in 1859, is credited with making the conception of panspermia even more popular as a possibility for the origin of life on Earth..
Very specifically, his ideas were related to extremely small particles, propagules or “vital seeds” traveling through the cosmos, propelled by the forces derived from solar energy, which could have accidentally reached our planet and filled it with life..
Despite being known particularly for his contributions to the biological sciences related to genetics - he received the Nobel Prize together with J. Watson for elucidating the structure of DNA - this British naturalist born in 1916, along with Leslie Orgel, also had contributions significant in theories panspermists.
The revolutionary ideas of both researchers proposed an alternative theory to that originally proposed by Arrhenius, in which the "vital seeds" would have reached earth after being deliberately sent by higher extraterrestrial entities..
He was an American astrobiologist, born in the mid-1930s, considered one of the most recent followers of the theories panspermists.
He believed that life on Earth arose from chemical and physical reactions between common materials throughout the cosmos and that it could have happened or could happen in any other part of it..
In his most important ideas, Sagan proposed that the answer to the main questions regarding the origin of life lay in the clouds of Venus, where according to him favorable conditions could be found for the proliferation of microbial life.
Radiopanspermia, also known as classical panspermia or Arrhenius panspermia, is based on the original ideas of Arrhenius, who proposed that life did not originate on Earth, but elsewhere in space and that it was "seeded" on this planet from "seeds" loaded with elemental forms of life.
According to this theory, such elemental forms -bacteria or highly resistant microbial spores- came to earth from outer space by traveling driven by electromagnetic radiation emanating from the sun's rays or from some other central star in another planetary system..
These "seeds", according to Arrhenius, would have reached the earth's surface, probably with favorable conditions for their germination, and would have given rise to the first forms of life, which would then have evolved into the more complex forms that we know today..
The main detractors of radiopanspermia are of the opinion that solar radiation would have caused the death of any vital element that "traveled" propelled by it, which is why they discredited the possibility that microbial spores could be traveling through the cosmos under the incidence of the sun.
It is a variant of panspermia classical raised by F. Crick (the same one who discovered, together with J. Watson, the structure of DNA) and L. Orgel between 1973 and 1981.
It was proposed as an alternative to Arrhenius's proposal. Both researchers established that the microbes that gave way to life on Earth could have arrived transported in an "unmanned spacecraft" directed by more advanced civilizations millions of years ago..
They also maintained that these propagules enriched this planet with life after having fallen into the primitive ocean, multiplying and evolving later.
This theory proposes that life originated from microbial seeds (microorganisms) that arrived on Earth inside rocks or meteorites, where they could be protected from the lethal ultraviolet (UV) radiation of the sun's rays.
It is thought that those rocks "loaded with life" that reached the Earth and that did not completely calcine after their impact with the atmosphere, could disintegrate and disperse on their way to the earth's surface, and along with them the microbial spores in their inside.
Lithopanspermia poses one of the most plausible scenarios for advocates of panspermia, as supporting scientists claim that interplanetary rock exchange is a naturally occurring phenomenon..
This is one of the variants most accepted theory, thanks to the discovery of remnants of meteorites originating from the Moon and Mars on the Earth's surface.
Unlike the other variants, molecular panspermia proposes that what actually travels through the cosmos are not highly resistant propagules or spores of various types of microorganisms, but rather organic molecules, which may have accidentally reached Earth.
This theory proposes that it would have been the conjunction of these organic molecules that could have originated the first forms of life, which would later evolve to become the complex beings that exist in our times..
Although the pasnpermia theory enjoyed many followers in its time, it also received great criticism and some of the main arguments had to do with the fact that:
- It did not explain the origin of the first life forms, but rather diverted attention to another place in the Universe, much more difficult to explain..
- There were serious questions regarding the possibility of survival of any living particle (spores or microbial propagules) in space, especially under conditions related to vacuum and solar ultraviolet radiation..
- Many considered that, since it could not be tested experimentally, it had more reason to be invalidated.
Yet No Comments