Making the Case For Microscopic Life In Meteorites 103
An anonymous reader writes "NASA scientist Dr. Richard Hoover claims he discovered evidence of extraterritorial life in a meteorite. He published his results in the March issue of Journal of Cosmology. In front of the article there is an official statement form the editor in chief: 'We believe Dr. Hoover's careful analysis provides definitive evidence of ancient microbial life on astral bodies some of which may predate the origin of Earth and this solar system. Dr. Richard Hoover is a highly respected scientist and astrobiologist with a prestigious record of accomplishment at NASA. Given the controversial nature of his discovery, we have invited 100 experts and have issued a general invitation to over 5000 scientists from the scientific community to review the paper and to offer their critical analysis.'"
Ah yes (Score:5, Interesting)
The Journal of Cosmology. They recently had an article called "Rouge Planet Discovered." About some Neptune-sized planet discovered in the oort cloud. They had this to say about the Bad Astronomy guy IN THE ARTICLE:
The torches and pitchforks crowd, led by astronomer-wannabe Phil Plait claims its not so. But then, Plait's most famous discovery was finding one of his old socks when it went missing after a spin in his dryer.
Sounds like a real reputable source.
As a biochemist, I've done extremely thorough research into the abiogenic origin of life. Earth, as it was, had all of the necessary building blocks for the formation of life. This "article" is pretty devoid of information, akin to a creationist saying "it was God because I believe it to be!"
Seriously slashdot editors, what the hell is wrong with you that you can't seem to do a basic source check?!
"Journal of Cosmology"? never heard of it. (Score:4, Interesting)
Doesn't necessarily mean this isn't true; but it raises suspicion.
Re:Ah yes (Score:5, Interesting)
The Journal of Cosmology does have an amateur feel about it, but that doesn't necessarily mean that all articles in it are junk. My former supervisor published a paper there with a member of the Jet Propulsion Laboratory (Mike Russell) as co-author on the origin of life.
As a biochemist, I've done extremely thorough research into the abiogenic origin of life.
Really? I have a degree in biochemistry, yet I wouldn't say that necessarily gave me any special insight into abiogenesis. It's closer to geology than biology, I would think.
Since I liked it very much, I'll mention again on ./ the talk given by Nick Lane on the origin of life and the origin of multicellularity. Although his expertise is in mitochondrial energetics, he gave a nice summary of recent research (including Russell's work). Although most schemes are quite speculative, the one he outlined involved the common mineral serpentine acting as a kind of reaction chamber for primitive metabolism involving proton gradients and methanogenesis.
So, although conditions on the early Earth may have made chemical life inevitable, that doesn't mean this paper is nonsense, nor is this journal worthless just because of some slightly odd papers published in it.
Re:"Journal of Cosmology"? never heard of it. (Score:5, Interesting)
From a quick google, it seems that Hoover already announced his "discovery" at least back in 2007, if not before:
http://www.panspermia.org/hoover2.htm
Richard B. Hoover of NASA/NSSTC announced today the discovery of evidence for the detection of a fossilized cyanobacterial mat in a freshly fractured, interior surface of the Orgueil carbonaceous meteorite. Many of the images presented were obtained 21-23 July 2004, using the Field Emission Scanning Electron Microscope at NASA's Marshall Space Flight Center in Huntsville, Alabama. The announcement was made in Denver, Colorado at the "Instruments, Methods, and Missions for Astrobiology VIII" (Conference 5555) at SPIE's International Symposium on Optical Science and Technology (its 49th Annual Meeting).
Re:Ah yes (Score:5, Interesting)
You've got a degree in biochemistry and you think abiogenesis has more to do with geology?
I call bullshit.
My point was actually that "I a have a degree in X" is argument from authority - much as I dislike the formal argument ..er.. memes, tropes, whatever.
I'll expand on my point a little:
Firstly, life is a complex system which continually repairs itself, and maintains a boundary separating itself from the environment. Alternatively, it is a series of positive feedbacks (explosions) controlled by negative feedback (death). Whatever definition is used, there is a clear principle that life comes from life - cells reproduce to make other cells; viruses hijack cellular machinery to make copies of themselves; etc. See Steven Rose on 'Lifelines' where he argues that the cell, not the gene is the fundamental unit of selection
So, clearly, some system nearly as complex as a living one was needed to 'initiate' life. The only possibility is a geological system. Now Graham Cairns-Smith (oddly enough, also at Glasgow) considered clays to be the template for ribozyme synthesis, with selection on those RNA molecules that stabilised or protected efficient clay replicators. He came up with the metaphor of a rope to illustrate the transition from system to system - clay to RNA to DNA to cell. In this metaphor, no 'strand' (system) stretches from one end of the rope to the other (which is an axis of time) but 'hands off' to the next system.
In Russell's theory, inorganic minerals form the boundary of proto-cells, and carry out primitive metabolism. Various iron/nickel sulphur minerals could have preformed the necessary redox reactions and proton gradients necessary for the energetic systems. Cooperation with short peptides in an autocatalytic cycle that generated longer protein-like catalysts was a possible method for bootstrapping enzymes. Personally, I don't see that there is a problem of which out of RNA and protein came first - perhaps both evolved at the same time and cross-catalysed each others autocatalysis.
In summary, the interface between life and non-life must necessarily involve a lot of geochemistry and geology. That's not to say that understanding of biochemistry is unneeded : many redox enzymes contain what are essentially nanocrystals of between 4 and 10 atoms that carry out essential parts of the reaction. Further, there is a PhD student in my lab who works on coenzymes (vitamins, essentially) who has done interesting work on the conservation of these coenzymes in evolution - perhaps there are some clues there as to the first mechanisms to arise to do things like C-C bond formation or peptide hydrolysis.
Re:be very, very skeptical (Score:5, Interesting)
Re:Ah yes (Score:3, Interesting)
The reason this is plausible is simple. If abiogenesis is indeed likely, then it is likely that it happened long ago and that traces of life can be found throughout the Oort cloud and beyond, because there are literally billions of years for it to cross the interstellar distances at the speeds of outgoing shock waves from supernovas and outgoing solar wind. In that case it might be a race, but fully formed organisms preserved in comets and other leftovers of leftovers of exploding star systems would have a huge advantage over local organisms that appeared from abiogenesis, which would be extremely primitive (and hence vulnerable) for a time.
If abiogenesis is in fact unlikely -- and of course we have no explicit model for abiogenesis that is yet accepted as being particularly plausible or probable in the sense that it is well supported by either evidence or even good seat of the pants statistical models or computations, so it might well be rather unlikely -- then even if it is unlikely that life arose on Earth (say, one in a million) the Galaxy as a whole has probably had tens to hundreds of millions of shots and life has arisen tens to hundreds of times, and every life-bearing planet very likely sheds "life" into its galactic vicinity at some nontrivial rate, especially in catastrophes such as when it is struck by an asteroid or blown away.
I therefore think that the meteor evidence is highly intriguing. To be truthful, I'd think it very odd if meteors and comets and dust particles from the Oort cloud on out did not have evidence of life -- that would suggest that life is somehow unique to Earth, which is most improbable. A chain reaction spread of life from one or more nucleation points that spontaneously appeared in a very large sample space indeed seems at least as plausible in the worst case, and far more plausible overall, given a state of near complete ignorance about the abiogenesis process itself.
Of course this could change -- somebody could come up with an evidence-supported model for abiogenesis, or a computationally plausible mechanism, or demonstrate it in the lab (at which point we could compute the probabilities a bit better). Or we could start to find evidence of life in all sorts of rocks that have never been anywhere near the Earth, once we manage to get out there and visit them. Or a big meteor shower could give off green light that blinds everybody who watches it and the next few days these big tree-people with sharp spiky things could sprout up and start eating people. Evidence, in other words, should be our guide here, not a personal bias towards local abiogenesis versus abiogenesis long ago and far away. Life is probably around ten or even eleven or twelve billion years old in the visible Un
Re:Ah yes (Score:4, Interesting)
somebody could come up with an evidence-supported model for abiogenesis, or a computationally plausible mechanism
Dr. Jack Szostak is your man. No ridiculous probablities, no supernatural forces, no lightning striking a mud puddle, just chemistry [youtube.com]. There is no clear line where complex organic chemistry suddenly becomes alive. Abiogenisis is not the improbable miricale of a single microbe popping into existance that happened once at one specific place, it's a constant process of increasingly complex organic chemistry that occurs in newly formed oceans. Given the theory in the video it follows that microbial life in the universe is almost as common as liquid water, it's just that (so far) we haven't been able to visit anywhere with liquid water. It also follows that it's highly likey that micobes did arrive on a young Earth via comets (and still do) however it also likely that the early Earth's ecosystem ate them.