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Sunday, April 24, 2011

Crick’s Joke

Chapter 6G

Crick’s Joke

I was unable to secure permission from the Journal of Cosmology to publish in this blog the 24 commentaries on Richard Hoover’s claim to found cyanobacteria in several meteorites. The gentleman who replied did, however, invite readers of the blog to take a look at the journal. These are the references. The online version is free.

Journal of Cosmology, 2011, Vol 13, March, 2011

I should add that the Journal of Cosmology has devoted several issues to panspermia and related topics. I will have to take a look and may perhaps return to this subject in a future posting.

In the meantime, however, I would like to remark, almost in passing, why the whole panspermia movement seems so perplexing to me. I will begin by expressing a nagging doubt about Hoover’s Cyanobacteria claim. From what I could tell, although as I said I will have to read more, Hoover’s claim seems to be based on the physical similarity between the structures he found in meteorites and Cyanobacteria in our planet. The “alien” pedigree is established by the fact that such structures exhibit only 8 of the 22 amino acids we would expect in terrestrial life. It seems to me, then, that even if those structures were indeed fossils, it is a long stretch to classify them as Cyanobacteria. Clearly, they cannot be Cyanobacteria: they don’t have the same proteins, for they don’t have the same amino acids, thus they cannot be the same kind of beast. Think of it another way: they must have radically different proteins, therefore, since genes code for proteins, they must have radically different genomes. Perhaps the classification is given because those structures, when alive, if they were ever alive, also engaged in oxygenic photosynthesis. But I do not know how that could be established from physical similarity.

Now, most defenders of panspermia promote the idea that terrestrial life did not originate on Earth but came from elsewhere. One wonders what kind of evidence they could have for such a claim. It is normally based on two assumptions:

(1) That life could have survived journeys of millions of years before landing on our planet;

(2) That life could not have started on Earth.

The first assumption is bolstered now by Hoover’s evidence for Cyanobacteria. But as I pointed out in my previous posting, Hoover’s findings do not support the notion that terrestrial life came from somewhere else, since presumably they established that those structures are not relatives of terrestrial life forms at all (only 8 amino acids in common, etc.).

The second assumption is rather astonishing. We really do not know how life begins. So how can these people argue that life could not have begun here?

They say that there was no enough time for life to evolve here from organic compounds, that the conditions were not right, and so on. But their reasoning seems very faulty to me. I will try to lay out my objections with some care in my next posting, and perhaps some readers who disagree with me can spot faults with my own reasoning and thus improve my understanding.

I would like to add at this point, though, that some of the more specific claims made by the advocates of panspermia make them lose scientific credibility. I will merely mention a couple that I found in a side article by Lana Tao in issue of the Journal of Cosmology that began this detour a couple of postings back. I will point out next time why they are not scientifically credible.

C. Wickramasinghe: "What we have developed and proposed in this text is a cosmic theory of evolution which completely overturns Darwinism." This appears in a section titled THE DEATH OF DARWINISM, no less.

R. Joseph: “Evolution is not random but is instead the replication of creatures which long ago lived on other planets."

R. Joseph: "Just as apple seeds contain the genetic instructions for the growth of apple trees, these genetic seeds of life contained the DNA-instructions for the Tree of Life, and the metamorphosis of all life, including woman and man: the replication of creatures which long ago lived on other planets."

I will close by remembering Francis Crick funny account of why we will never be able to figure out how life began. Life came to Earth from another world. In that world, scientists developed a synthetic form of life that could withstand the long journey through space. But such life could have never arisen naturally. So by studying natural phenomena, we will never get a clue, for the conditions necessary to bring such life into existence do not naturally exist.

And Gunther Stent quipped that if Francis Crick, the greatest biologist of the 20th Century had not been able to discover how life began, no one could.

But on the shoulders of giants….

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.