Search This Blog

Sunday, April 10, 2011

More on Meteorite Bacteria Fossils

Chapter 6f

More on Meteorite Bacteria Fossils

Some readers have expressed great interest in the controversy surrounding Richard Hoover’s claim to have found fossils of cyanobacteria in several meteorites. I have asked permission from the Journal of Cosmology, the online journal that published Hoover’s paper, to reprint the 24 commentaries on Hoover’s alleged discovery. Once I hear from the journal, I will let you know. I said “alleged” two sentences ago because I do not have the technical expertise to critique Hoover’s analysis. I could mention, however, that of the 24 commentaries, only about 8 are by people who do seem to be technically qualified to pass judgment on the quality of Hoover’s work. The others, which include pieces coming from Ph.D.s in many fields, mostly deal with what they take to be the implications of Hoover’s work. Several come from advocates of the panspermia hypothesis, i.e. that life is everywhere and spreads by hitching rides in meteorites, asteroids, comets, etc. Those advocates are also proponents of exogenesis, i.e. the view that Earth life did not originate on Earth but came from elsewhere. Those people believe that Hoover’s work confirms their views.

Of the commentators who actually take up the technical details of Hoover’s paper, about four give him a clean bill of health, mostly on the question of whether his findings could have been the result of contamination of the meteorites by Earth life, although some of them are also struck by the great physical resemblance between the structures he found and cyanobacteria. The reasons for concluding that there was no contamination were (1) lower levels of nitrogen than normally exhibited by modern bacteria, and (2) the presence of only 8 amino acids instead of the 22 employed by living things in this planet. The other four were rather skeptical about his experimental methods and his reasoning, even when expressing interest in his work.

A more definitive assessment would require the kind of peer review normally reserved for results of the upmost importance, a review that would include the experimental work proposed by some of the skeptical commentators. Unfortunately it seems that the major journals and NASA have grown gun shy after the bruising battles concerning the Martian meteorite I have discussed in previous blogs.

Perhaps in my next posting I will be able to include the 24 commentaries. Otherwise I will return to my regular line of thought derived from my manuscript in progress, The Dimming of Starlight. Today, however, I will bring up a couple of comments relevant to the panspermia and exogenesis hypotheses.

One of the commentators though that the meteorites in question were likely Martian. Another though that they could be from the Earth itself: they were thrown into space, and finally they came back. Unless this possibility is excluded, Hoover’s findings would not help the panspermia hypothesis. Now, it seems to me that if Hoover’s structures are indeed extraterrestrial fossils, then this extraordinary finding would support the view that life may be common in the universe. It does not support the exogenesis hypothesis all that much, for, after all, Hoover would have only found fossils, dead things, not living bacteria that survived the long journey through space to Earth (or even bacteria that made it alive to Earth and then died here). Dead is dead. Maybe live extraterrestrial bacteria could make it to Earth and survive, but we cannot infer that from the fact that dead ones made it. If they are indeed bacterial fossils to begin with.

Second, the confirmation of Hoover’s structures as fossils may actually seem to go against the exogenesis hypothesis, for the very strong reason already given to show that they are not the result of contamination, namely that they have only 8 amino acids instead of the earthlings’ 22 customary amino acids. That is, they are radically different from Earth life, even if they have enough similarity to call them life. But if they are radically different from Earth life, we have no evidence that life on Earth has an extraterrestrial origin.

Sometimes, I should mention, the words “panspermia” and “exogenesis” are used as synonyms. That is, panspermia is the flag around which the proponents of the extra-terrestrial origin of life on Earth gather. One of the commentators, the former Appollo 17 astronaut and U.S. senator, Harrison H. Schmitt, wondered why these people are adamant that life could not have evolved independently on Earth. Indeed I wonder too. But more on this next time.

No comments: