May 2001
Did life arrive from outer space? Proponents of Panspermia think so. Source: Microsoft Images.
Editorial Comment: This article summarizes Evolution of Life: A Cosmic Perspective, an original paper by Chandra Wickramasinghe and Sir Fred Hoyle posted on this site (click on above title to read their paper). There, readers will also find a link to the commentary by the peer reviewer of that paper, which provides counterpoint views to the authors’ controversial ideas. The hypothesis, called cosmic ancestry/panspermia, posited by the authors is not widely accepted by the mainstream scientific community. It is published on this site in consideration of the authors’ distinguished contributions to science to date and to provide an opportunity for both scientists and the public to evaluate ideas presented in their paper.
Recently, scientists at University of California, Berkeley, have shown that organic molecules travelling through space on comets could have survived their impact with Earth and could have seeded life on our planet. The university will also conduct research in the near future on whether cometary microorganisms could survive the impact and the results may support the hypothesis presented by Wickramasinghe and Hoyle. To read more about this research, go to the “learn more” links that follow this article.
Where did we come from?
The radical answer proposed by Fred Hoyle and myself in the late 1970s was that we came from space!1 Our genes and those of all living forms on Earth were brought here by comets, neatly packaged within cosmic microorganisms. The idea was not plucked out of the skies, but was the result of careful analysis of astronomical and biological data over several years. In the paper Evolution of Life: A Cosmic Perspective, posted on this site, Fred Hoyle and I present the main technical arguments in support of our views.
Initial resistance to this theory stemmed from two reasons:
- It flew in the face of a long-established paradigm of an Earthly origin of life from organic soup.
- The marriage of biology and astronomy was fraught with difficulties. There was a sociological problem that arose from the artificial separation of scientific disciplines within University departments. Life was considered the prerogative of biologists, the Universe of stars and galaxies that of astronomers. And it was decreed by some unwritten law that never the twain shall meet.
How did the Cosmic Ancestry hypothesis develop?
The facts always led the way for Fred Hoyle and myself. The information content of life, even in its simplest form, had to be reckoned with on a superastronomical scale. So we argued the molecular arrangements bearing this information could not arise under the hopelessly diminutive conditions that existed in a “warm little terrestrial pond.” The origin of life must surely involve the combined resources of all the stars in all the galaxies of the Universe. Once originated, however, the dispersal and distribution of life across cosmic distances would be assured by virtue of the well-attested resistance of bacteria to the harshest of conditions in space.
The next fact in our favour was that life appears on early Earth when comets were colliding with great frequency and when the planet had neither a stable ocean or atmosphere.2 The conditions on Earth at this time were manifestly unsuitable for producing even the chemical building blocks of life indigenously. In our picture it was easy to see how both the organic feedstock of life and life itself could have arrived on Earth along with the colliding comets.
In the late 1970s there was also a growing body of evidence for biochemical substances in the interstellar clouds of deep space.3 Astronomical observations, first made by my brother Professor Dayal Wickramasinghe of the Australian National University and David Allen, showed in 1979 that cosmic dust had a composition similar to dried out bacteria.4 They also showed the same conclusion to hold for the dust that flowed out of Halley’s comet in March 1986.5 The discovery that clinched our hypothesis was the realisation that one third of all the available carbon in interstellar space had to be tied up in the form of hollow organic particles with the average size of a bacterium and with spectral properties that could not be distinguished from biological material. No other process apart from biology seemed reasonable to invoke in order to produce the vast amount (some 1030 tonnes) of bacteria-like matter that existed in our galaxy alone.6
So the logic that emerged in the early 1980s from our work was as follows:
Life with all its basic genetic information originated, not on Earth but on a grand cosmic scale.
Viable bacterial cells are present in interstellar clouds (they appear as dark patches and striations against the background of the Milky Way).
Bacterial cells are included in the clouds that collapse to form stars, comets and planets.
Anaerobic bacteria replicate and increase their numbers vastly in the warm liquid interiors of comets.
Comets (100 billion of them in our solar system alone) shed viable material onto the surfaces of planets like Earth, and also return amplified biological material back in to space for the continued operation of steps 2-5.
What could happen if life continues to arrive on Earth?
If, according to our view of astrobiology, we were indeed made up of space-bugs several important consequences would follow. The continued arrival of comet debris to Earth at the rate of some 100 tons per day must surely bring in new bugs. Such bugs could do one of three things:
- They fall to the surface and do not interact with terrestrial life forms.
- They interact with terrestrial life by adding to the genomes of plants and animal, and thus assist evolution.
- They could attack terrestrial lifeforms and lead to epidemics of disease.
A trend to accept at least some of these conclusions began just after the announcement in 1996 by NASA scientists that they may have found evidence of bacterial fossils in a meteorite that came from Mars.7 Although this claim itself is still in dispute, it would nevertheless seem to have signalled an important and long overdue paradigm shift - from a purely Earth-based theory of life to one in which cosmic inputs are considered to be a vital component.8 The variants of the theory currently being discussed range from the concept of organic chemicals alone coming from space to the concept that ready-formed microorganisms arrive from comets.
What can the study of Astrobiology accomplish?
The transfer of microbial life between objects within the solar system is nowadays taken for granted. Projects to search for life on planets and comets are under way. An Astrobiology Institute under the auspices of NASA was set up a few years back and other countries are following suit. Recently the first Centre for Astrobiology in the UK was started at Cardiff University in Wales. Astrobiology has moved into the realm of conventional science.
A decisive experiment to show that microbial life is still arriving to Earth via comets is being planned by ISRO (Indian Space Research Organisation) in collaboration with the Cardiff group. The aim is to collect large quantities of stratospheric air using sterile equipment (cryopumps) carried aboard balloons, and to search these samples for hints of alien microbial life.
The first unequivocal detection of such alien life would undoubtedly mark the most important turning point in Science for many centuries. Its importance could be on par with the discoveries of Kepler, Galilleo and Newton in the 15th and 16th centuries, and those of Darwin in the 19th century.
In the broadest perspective, the acceptance of the idea of life existing outside Earth would have profound implications for the future progress of the human race.
- Humankind would be forced to accept the role of being just another lifeform on a quite ordinary planet, Earth, which is one of many billions of similar planets orbiting countess stars in the Universe.
- Our perceptions of ourselves, our sense of self-importance and self-esteem would be dramatically altered when the full importance of the discovery of extraterrestrial life comes to be recognized.
- At long last we would be forced to accept our true ancestral links with the cosmos, hopefully leading to the emergence of an all-encompassing cosmic world-view.
Editorial Comment: This article summarizes Evolution of Life: A Cosmic Perspective, an original paper by Chandra Wickramasinghe and Sir Fred Hoyle posted on this site (click on title to read their paper). There, readers will also find a link to the commentary by the peer reviewer of that paper, which provides counterpoint views to the authors’ controversial ideas.
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