Hey, how about these article titles?
Comet Impacts Really Could Have Been the Catalyst For Life on Earth
Comet Impacts May Have Produced The Building Blocks For Life On Earth
We Now Know For Sure How Life Began on Earth
We’re getting this sudden flurry of articles touting the contribution of organic molecules from cometary sources to the origin of life on Earth. They’re all bullshit. The media hype machine is going crazy again over science the journalists haven’t thought through.
There’s nothing wrong with the core of the original paper that sparked this frenzy of nonsense: the investigators showed that the energy of comet collisions can drive the assembly of amino acid monomers into short linear peptides. They made extremely cold pellets of glycine ice and fired them with a propellant gun into a block, and presto, they got tripeptides out of the collisions. I can believe that.
What I can’t believe is that early cellular biosynthesis was catalyzed by comet impacts. This explains nothing. It is not enough to postulate that there was, once upon a time, a cold soup of organic subunits in the ocean, that just sort of congealed into life — it doesn’t work. The authors made no calculations about the concentrations of their tripeptides in the prebiotic ocean (it would have been an exceedingly thin, dilute soup), don’t consider that these compounds were probably degrading as fast as comet-smashing was making them, and that their mechanism does not say anything at all about what reactions early precursors to life would have been using to synthesize peptides. I’m certain the answer didn’t involve waiting for a giant ball of ice to smack into the protocell.
For some reason, journalists and the public love these scenarios of cosmic forces colliding in big explosions to create life — it’s as if they desperately want Michael Bay to be in charge of biology. It’s not how it would have worked. If you want to look for answers to the origin of life, you need to look at conditions that generate a gentler flux of energy that is a better analog to metabolism. It’s about flow, not bang.
The best summary of how actually abiogenesis would have occurred is Nick Lane’s The Vital Question: Energy, Evolution, and the Origins of Complex Life
Or you could try reading a paper by the always-entertaining William Martin, if you’re in more of a hurry.
The very familiar concept that life arose from some kind of organic soup is 80 years old and had best be abandoned altogether. The reason is that life is not about the spatial reorganization of preexisting components, it is a continuous chemical reaction, an energy-releasing reaction, and a far-from-equilibrium process. The proposal that life arose through the self-organisation of preformed constituents in a pond or an ice-pore containing some kind of preformed prebiotic broth can be rejected with a simple thought experiment: If we were to take a living organism and homogenize it so as to destroy the cellular structure but leave the molecules intact, then put that perfect organic soup into a container and wait for any amount of time, would any form of life ever arise from it de novo? The answer is no, and the reason is because the carbon, nitrogen, oxygen, and hydrogen in that soup is at equilibrium: it has virtually no redox potential to react further so as to provide electron transfers and chemical energy that are the currency and fabric of life.
If not soup, what? Life is about redox chemistry, so the site and environment of life’s origin should be replete with redox reactions. Alkaline hydrothermal vents provide a good model for understanding early chemical evolution because they have some similarity to living systems themselves. Perhaps similar to some types of hydrothermal vents observable today, such as Lost City, alkaline vents during the Hadean would have offered a necessary and sufficient redox potential (in the form of the H2-CO2 redox couple) and catalytic capabilities (in the form of transition metal ions) to permit organic synthesis at a specific location in space and stably over geological time to give rise to the chemical constituents of life and to foster the transition from geochemically contained chemical networks to bona fide free-living cells. Why, exactly, are alkaline hydrothermal vents conceptually attractive in the origin of life context? There are a number of reasons, many of which are old as the discovery of vents themselves but they remain current.
These ideas have been around for years, but they never seem to get the kind of press extraterrestrial bullshit gets. It’s the lack of explosions, I suspect.
KABLOOIE!!!
Sorry, I just felt there was a lack of explosions. I’m all better now.
No explosions (well, not yet — the mildly deranged penguin is still sleeping), but it is now raining dogs, cows, mice, the smaller sorts of whales, and what looks to be a very confused kangaroo at the moment — proof, PROOF!, that life did rain to earth from the skies above…
(As to why every critter except the kangaroo — perhaps this is why it is confused? — is a mammal, I’ve no idea. Maybe there are different sorts of impacts for different clades(?) of beasties?)
Thank you, PZ. This one goes in the save file. I am not very science literate, regretfully (although I’m considerably more so now than I was ten years ago). I did not know about this geochemistry. The idea of the primordial soup giving rise to life forms is pleasing, but always made about as much sense as the idea that identifiable beasties could arise out of one of my stove-top concoctions. Actually, they can if I leave the pot in the fridge too long. I refer to those as my science experiments. By the way, I named my homemade soup enterprise Primordial Soup.
For those of us who have forgotten our high school chemistry, redox reactions are oxidation-reduction reactions:
So now we know why we rust.
Just waiting for the Creationists to claim this as , that this proves Goddidit by slamming a comet into the primordial soup.
I’m tempted to assert that the journalists phrased those titles, that way, attempting to appease the anti-science crowd (to increase their readership, eh). but no…
I’ll just leave that assertion right here (for speculation), thankyouverymuch.
…
otherwise__
it is interesting why so many require such an event to be a single cataclysmic event, rather than accepting the “continuous flow” model. Leading to questions of Bay’s rise to fame by throwing in many *boom*s into his films.
(Boldfacing mine.) I can just about imagine some cdesign proponentsist latching onto that: “Silly biologists think chemicals are alive!” or “Darwin says atoms mutate!” or…
blf@2: Umm, the last time I checked, kangaroos were mammals. They’re not placental mammals, but they’re still mammals.
Interestingly, far-from-equilibrium conditions also seem to be necessary for the preponderance of matter over antimatter. So, no boring old primordial quark soup in the early universe.
inquisitiveraven@7, Well, I did say it “looked like” and seemed to be “very confused”. It has since slithered off, leaving behind a trail of bubbling green slime, so it’s now a bit hard to work out what it was. The green slime has since washed into the sea and apparently upset the ducks, who are quacking more madly than usual. The green slime is quacking back. The tourists are taking selfies with a background of other tourists taking selfies.
Enormous cosmic entity of unfathomable power arrives on earth, touches something, and POOFS life into existence.
It just seems that there are some people who are emotionally drawn to that kind of narrative….
… it’s as if they desperately want Michael Bay to be in charge of biology.
Should any such scenario reach the level of plausibility, we’ll have to call it Bayology.
If only Nick Lane had mentioned exploding hydrothermal vents somewhere…
***
slithey tove,
Nah. Most likely they will use this to mock for believing something so ridiculous. I can see them now:
That sounds more like how a typical creationist would react. After all, burning straw men is their favorite thing ever. It doesn’t really matter if they have to build the straw man themselves or if it is handed to them by clueless science journalists.
From that foetid puddle of warm and slimy primeval soup life was finally forced to take to the land owing to the behaviour of the Grasshopper clan, who were forced out because the neighbourhood committee said they were lowering the tone of the community, and in general giving putridness and stench a bad name.
And you thought original sin was the cause of humanity’s malaise.
Well, curiosity led me to put on the gloves and delve a bit into the creationist/ID webosphere to see if there were any reactions to this recent frenzy of nonsense. I didn’t find anything, but the cdesign proponentsists at Evolution News are very excited about the octopus genome.
I’ll save you some time. They think that without whole-genome duplication scientists are only left with magic to explain genomic novelty. No, I’m not kidding.
Yes, they’re saying all of that is magic.
Also, convergent evolution is a cop-out. Out of what, I don’t know, but it is. Something about . Yes, I’m quoting them. Don’t ask me what that’s about either, I’m very confused. Remember, I navigated through AiG, UD and ICR before getting back here. My brain is still recovering.
I am pretty sure that the creationist biggest problem is that they try to force scientific explanations onto their belief of what nature of reality is and of course it just does not make sense.
In a similar way the popular press deliberately or unconsciously avoids the implications of the discoveries of science about reality and gravitates around interpretations that are not so in conflict with ancient explanations and superstitions.
Let’s see, redox chemistry, check. Moon close to Earth with large tidal forces, check. Chiral minerals and the non-parity of the weak force, check. Very interesting to combine the data and see what falls out.
Science pffft – no sense of the dramatic.
“I am become death, the destroyer of worlds.” – J. Robert Oppenheimer
Personally, I think Nick Lane’s hypothesis is so much cooler than the asteroid idea because it says we can see the imprints of the first life in our cells today, and it explains a lot about why we are the way we are. It’s amazing to think that I share my mechanism of energy production (proton gradients across membranes) with the first living organism.
Or, it could be that an asteroid deposited some amino acids on earth once, and then never had any importance in the history of life again. Boring.
I must say though that this comet idea (or any other idea regarding raw materials for life arriving on earth) does not contradict the alkaline vent hypothesis described by Nick Lane and others.
Any organic precursors delivered by comets, and any polymers synthesized as a consequence of a comet impact, if they survive, could easily percolate down into the vent regions and be incorporated into the vent chemistry, which, per that hypothesis, ultimately produced the first life forms.
Reminds me of this bullshit:
https://pbs.twimg.com/media/ByKCGO6CAAAk5T6.jpg
Whenever I see this posted somewhere I feel the urge to punch the poster in the face in a futile attempt to beat the stupid out of them
There was a recent paper (cant find it alas) on spontaneous RNA chains. The longest were created at -18C IIRC. The early earth had much larger tides so I can imagine a glacial bay with huge volumes of finely ground material amongst the ice slush at the end of a bay. I’m guessing an alkaline hydrothermal vent could combine William Martins stuff with a starter kit of other bits too – including very high salt gradients for other actors.
Oh, isn’t science boring? Science journalism is so much more fun!
@12
Or, even better, exploding hydrothermal vents being attacked by giant radioactive sharks! I know there’s a slight temporal problem with that, but that shouldn’t bother science journalists too much.
But everybody likes explosions!
Most people don’t understand chemistry or redox reactions, but they might recall the primordial soup experiments, and we all love explosions, and the idea of comets crashing into the earth is exciting and comprehensible in some way.
It’s all the Myth Busters’ fault. They could hardly do anything without explosions.
Giant radioactive alien sharks!
That arrived on earth by comet!
Yes! That solves Kevin’s temporal problem too, because the sharks are alien.
Kevin, Amphiox, we’re on to something here. I feel it. I’m not sure if it’s an abiogenesis hypothesis or a bad sci-fi movie, but it’s definitely something.
If Comet started life on Earth wouldn’t that mean we evolved from reindeer?
There’s no appropriate place to post this, but this thread seemed the least inappropriate, so…
Female mice “can be turned lesbian” by deleting gene.
I smell shoddy science journalism, but the journalist is at least careful to state that “While oestrogen masculinises the brain in mice, it does not have the same effect on humans.”
Hilariously, the gene is called “the FucM gene”. Who said scientists don’t have a sense of humour?
Thumper
That article could work over here
http://freethoughtblogs.com/pharyngula/2015/08/01/discuss-through-a-feminist-lens/comment-page-1/