Very interesting. I hope that these processes are actually experimentally replicable enough that we can at least get a plausibility determination. As we know in the hard sciences (i.e. physics, chemistry, mathematics), even the most convincing theories typically need a lot of underlying experimental work to keep the theorists from marching off into fantasy land. That tendency is an unfortunate side effect of our limited cognitive abilities.
Not really useful, life can arise in only two ways, spontaneously, whenever conditions are right, or miraculously only once, only one place and then spread. The key events lead from inanimate to animate, all else is a diversion.
I think it is a step in the right direction to place the origins of lifes specific steps in order. If the most simple life is a prion or a virus how do you get from a greasy bioite mineral to a cyclic system running on available chemical energy. Make a flow chart. If the geological-chemical origin of life is true, then we should find the first stages of life around the oldest geological formations. You should be able to guess where it resides. Can't find a trace from the bombardment? Then the origin is further back in time and distance and must be a cosmic origin. Life on this planet is very rare. Calculate the volume of life versus the volume of earth. Comet material would have to have a high concentration of life pieces in order to seed life. Perhaps looking at the orbit of solar systems that have been in near collision with our solar system will show exoplanets terraformed like our own. You still havn't found the origin of the complexity of life. Evolution is after life starts.
I have a hard time believing that the energy which a comet or a large meteorite capable of punching through to magma would release would allow the site to remain at a low enough temperature for liquid water to remain. If one hit in water the reflow would dilute and disperse any chemical payload that wasn't ejected.
I find it difficult to get past the anthropomorphic-biased sequence of presumed events. The author presupposes that the end product, eukaryotic life, is the reason for the precursors, RNA & proteins and then goes on to imbue them with purposeful actions such as enveloping themselves in membranes and communicating. These are the actions of the complex end product, life, not of oily bubbles and acidic carbon-based slime. RNA, sans life, is no more pre-determined to evolve than halite. This view merely pushes the mystical life spark on to RNA as the protogenerator of life without explaining how RNA gained a deterministic purpose to become life.
"Chatterjee discovered the Shiva Meteorite Crater, which was created by a 25-mile-wide meteorite that struck off the coast of India. This research concluded this giant meteorite wreaked havoc simultaneously with the Chicxulub meteorite strike near Mexico, finishing the dinosaurs 65 million years ago." Proposed. "Earth scientists in general remain unconvinced that the "Shiva Crater" is indeed an impact crater. For example, Christian Koeberl, a professor of impact research and planetary geology at the University of Vienna, Austria, regards the Shiva crater to be "a figment of imagination."[4][5] Currently, it is not recognized as an impact crater by the Earth Impact Database of the Planetary and Space Science Centre at the University of New Brunswick, Canada."
1. RNA is catalytically active on its own. The ribosome, for example, is able to polymerize amino acids without any of its protein subunits. RNAseP is another. Plausible prebiotic synthesis routes and extraterrestrial origins have been found for all the RNA nucleotides and spontaneous polymerization is possible on certain minerals like montmorillonite clay. Current research is also leading toward better and better general RNA polymerase ribozymes. These ribozymes are subject to Darwinian natural selection as those capable of replicating themselves faster would use up the precursor molecules and flourish over those with lower fecundity.
2. Encapsulation is not a purposeful event. It occurs spontaneously in solutions containing lipids due to their self-assembling properties. Cycled hydration and dehydration on surfaces is sufficient to encapsulate large macromolecules. This would easily occur on shores and rocks exposed to waves or tidal movement.
This theory is showing DNA in the first cells. I seriously doubt the first life had DNA. There's no way something as complex as DNA just sprang up full blown in the first life. My guess would be RNA came first.
Chatterjee is a cook, he is the one behind Protoavis [ http://en.wikiped...atterjee ] and the not accepted 'Shiva crater'. His ideas here is a cookbook on ideas already presented elsewhere.
Btw, hydrothermal vents produce lipids by themselves.
@axemaster: Too true. Since Lane & Martin already established that life clades within alkaline hydrothermal vents, these ideas are but a variant.
@adave: "Evolution is after life starts." Not a fact, chemical evolution is seamlessly led into biological evolution, see the established phylogeny above.
@Moebius: Indeed, that RNA was first is well established (and implicitly led to a Nobel prize for elucidating the RNA core of the ribosome protein translator).
As for the hilarious creationist trolling, it is this time notable that they can't publish their magic ideas in peer publication, simply because it is nonfactual and clash with how life evolved. The only result they get with their antics and inanities is deconverts from magic beliefs, see Dawkins's Convert's Corner.
I cannot add anything new to the discussion but that won't stop me. I am with Terrance Mckenna. Panspermia. There is something wacky at the foundations of our understanding of reality on this planet. Douglas Adams tried to express this feeling with his allegory of the mice doing subtle experiments on the scientists. Anyway, here is Mckenna's tale. Do try it-it will rattle your Ego-which is a good thing. http://www.youtub...RiVGfONU
Since we have had large recent and early impacts, where are the signs of life in some of the early rock still available or the most recent craters? Genesis of life should be possible more than one time. We should find the mineral changes caused by newly formed life at different ages. Stromatolites have had a very low rate of evolution in the past 3.5 billion years. How many steps do they take to exhibit life? If a virus is more simple, how many steps for the virus to step through its possible states before it inputs energy quanta again? There should be evidence of the generation of life existing over an epoch. If the answer is panspermia, life must still be preserved in rock, ice, or interstellar organic concretions in order to impact the Earth and live. It is hard to seperate life from its growth medium. If life grew best in water on the earth under high pressure, then wherever it began, the origin must have been the same. We are still left with a mystery.
@adave: The earliest (arguable) fossils are from a period right after the presumed late bombardment that shows on Moon, Mars, Mercury and if so have erased earlier rock records. It is the Isua BIFs which on microscale shows Fe oxidizers @ > 3.8 Ga.
If life is extant, later chemical evolution merely serves as nutrient. Already Darwin had grokked and formulated that prediction of why we don't see life forming still. This is no mystery at such, and it hasn't been for over a century.
Stromatolites bacteria consists of new species compared to the first we see, and those bacteria evolves as fast as others - faster than we, due to large populations. Stromatolites are, like viruses, more a niche than a specific set of species.
As I note above, where and how life evolved is likely solved now, by Lane & Martin, at the resolution that we are able to easily see (after 4 billion years!). To resolve more detail of how it happened, we need Russell's lab work, he got 8 MUSD from NASA to look into chemical reactors that works like the first life did.
[Refs: Like last time I'm out of time here. The Isua results are googeable. Lane & Martin: "The Origin of Membrane Bioenergetics", Cell 2012 - a must read!]
@Torbjorn - great article. I'd read the earlier works on alkaline hydrothermal vents, but had missed Lane & Martin's broader paper. Thanks for the reference!
axemaster
Oct 29, 2013