In the history of astronomy, views have evolved from clerically dogmatized Earth-central theory to Sun-central theory, to Black Holes and Big Bang. Similarly, views about the origin of life have evolved from Creation, to Earth-central theory, and now, or rather already quite a while ago – to Cosmic theory.

There is one important difference in the evolution of the ideas: while accumulating undeniable facts have lead cosmology inevitably to the modern grand view, the origin of life is, essentially, still limited to only Earth-based observations. There is no hard evidence of Life beyond the Earth, yet. The origin of life as a discipline is still at the stage of controversy between Creation and atheistically interpreted Evolution.

One may refer, though, to chemical evidence – apparent sameness of elementary and low molecular composition of Life on Earth and of dust-meteorites-planets. But this is sameness of chemistry, not necessarily evidence of life.

Here comes the note of reconciliation: If the chemistry, the periodical Table, is the same all around, would not the potential combinatorics of chemical bonding be everywhere the same as well? That is, the same potential spectrum of molecules and macromolecules, the nucleic acids and proteins may be the rule and not the exception. Given similar physical conditions and chemical environments one surely would expect similar molecular repertoires. One may speculate that chemical complexities may travel along rather different paths if conditions are different. But even in this case some very basic commonality of small molecules would still be there. Life based on chemistry does not have to be the same everywhere, considering the unimaginable size of a combinatorial universe of chemistry. However, in all possible forms it would, perhaps, fit to one simple definition of life (Trifonov, in press), based on Darwinian views: “Life is self-reproduction with variations”.

Thus, some form(s) of life, assuming its chemical unity, may and, probably, do exist on other planets and solar systems as Dr. Joseph (2009) and others have speculated. If true, then we just need some far reaching instrumental breakthrough to witness the outside versions of life.

Interestingly, Dr. Joseph (2009) is so much devoted to the “life begets life” principle, that the idea of abiotic origin is nearly completely denied. Abiogenesis is dressed in Augustine’s gown to make it appalling. It is “speculative hypothesis devoid of fact-based scientific support." But the same can be said about panspermia. In both cases one can present a wealth of supporting evidence, but no hard demonstrations, yet. Its true, as Joseph asserts that “No one has ever demonstrated that life can be produced from non-life." But no one has demonstrated panspermic life either. Demonstration of life, whether of abiotic origin (Earthly) or panspermic, should include the most basic features of life – self-reproduction and variation. The “many meteorites contain fragments of DNA” (presumably referring to nuclei acids and bases) and fossilized impressions suggestive of microfossils, are not a demonstration of life.

Still, both abiotic (life on Earth has abiotic origin) and panspermic views (life came to Earth from space) are intellectually attractive, and both may well be right. There is no reference to Miller (1953, 1987) in this otherwise well argumented review. Yet, the abiotic idea is very much alive. Those 10 amino acids of Miller make most of the mass of modern proteins (Trifonov, 2008). One should wonder – why? Following old Occam should not one pursue the reconstruction of the earliest steps of life from something already in hand rather than looking for some well designed contamination to come from space?

Dr. Joseph, by his own admission, does not concern himself in this paper with the origin of life other than to accept the possibility it may have formed on a planet or in an environment with a chemistry different from Earth. Instead he presents us with a concept of "life" which is perpetuated, as if it were an intrinsic feature of the universe. He makes an easy escape from the difficult question on how it started to begin with. Joseph (2009) also equates the abiotic and geocentric ideas which are principally different.

By accepting the “cosmopolitan” nature of life, why don’t we accept also the simple idea of multiple, even unlimited, life starts? Perhaps life has begun on many planets in many solar systems and in galaxies throughout the universe. Perhaps life travels between planets and solar systems which already contain life generated through abiogenesis. This does not rule out Joseph's hypothesis. It makes it more attractive.

To summarize: yes, “life on Earth may have come from other planets." However, if life came from other planets it was to join and compete with the life that also, quite likely, originated on Earth. And, likewise, life on Earth may have already started to invade (contaminate) space, and other planets, reciprocally.

References

Joseph, R. 2009. Life on Earth came from other planets. Journal of Cosmology, 1, 1-56.

Miller, S. L. 1953. A production of amino acids under possible primitive earth conditions. Science 117, 528–529.

Miller, S. L. 1987. Which organic compounds could have occurred on the prebiotic earth? Cold Spring Harbor Symposia on Quantitative Biology 52,17–27.

Trifonov, E. N. 2008. Tracing Life back to elements. Physics of Life Reviews 5, 121-132.

Trifonov, E. N., Origin of the genetic code and the earliest oligopeptides, Research in Microbiology, in press.