Abiogenesis, chirality and narrowing down the alternatives

In the great “mythmaking” that is the scientific process, discovering things about events long lost to history is done a little bit differently than the method might suggest in more mundane circumstances. We develop plausible hypotheses regarding events like the abiogenesis event that occurred here on Earth, and then test them rigorously attempting to falsify each one in turn. Like Sherlock Holmes, or Dr. House, we’ll get to the kernel of the matter by eliminating all the alternatives until we are left with but one plausible truth. We know we’re on the right track when predictions about certain aspects of the theory are demonstrable in laboratories.

We may never learn the exact nature of the exact abiogenesis event that led to us (among multiple possible such events) any more than we’ll know the exact daily routine, shape, facial features, birthday or date of death of the single individual last common ancestor (among multiple possible last common ancestors of that ancestor’s species) between us and chimpanzees, but we know (by genetic and fossil evidence) that we are not that far removed. This should not matter in the investigation of how it could have happened — despite the fact that there are many theories about the event of abiogenesis. We know the first chemicals breached that fuzzy boundary between “mere chemical reaction” and “self-perpetuating chemical reaction” — in other words, between non-life and life — so we know abiogenesis had to happen somewhere. If it didn’t happen here, and we got here by panspermia, then it happened elsewhere in the universe first, but it happened once at the very least.

New research has been very promising as of late with regard to the greatest mystery our planet yet holds, potentially unlocking each of the sub-mysteries one at a time with plausible answers. One of these sub-mysteries involves the chirality of all life on Earth — every amino acid this planet uses as its biological Lego can exist in a right-handed or a left-handed form and would spontaneously form either one at identical odds, but every speck of life on this planet uses only the left-handed version. With our ever-improving knowledge of the early environment of the planet, we’ve discovered that aspartic acid trends sinistral, creating left-handed versions in large quantities in a crystalline structure under those conditions. This certainly does not confirm the theory, but it provides a good hypothetical “seed” that explains how the amino acids that form us all tended to be left-handed.

There’s also the question of why those simple building blocks like aspartic acid might have influenced the other amino acids that self-generated in the environment to follow suit in their chirality. So, scientists built on the earlier result and introduced the left-handed acids into an environment with equal proportion left- and right-handed amino acids, and found the left ones crystallized much like the aspartic acid crystal in the earlier experiment.

“These amino acids changed how the reactions work and allowed only the naturally occurring RNA precursors to be generated in a stable form,” said Hein. “In the end, we showed that an amazingly simple result emerged from some very complex and interconnected chemistry.”
The natural enantiomer of the RNA precursor molecules formed a crystal structure visible to the naked eye. The crystals are stable and avoid normal chemical breakdown. They can exist until the conditions are right for them to change into RNA.

This experiment had every possibility of falsifying the earlier hypothesis but it did not. More research will either disprove both these hypotheses, or confirm them repeatedly over many iterations until our confidence level has increased so that they’re the best plausible explanations. Or, who knows? Perhaps we’ll one day unearth some new evidence, and we’ll need a better explanation to incorporate that new knowledge.

That’s how science works.

Abiogenesis, chirality and narrowing down the alternatives

How we know things in science, and how we can know things about abiogenesis

Nicked from astrobio.net on the Miller-Urey experiments. That's the actual equipment used

On this blog post over at Greg Laden’s, I’ve made a damn fine effort (if I do say so myself) at explaining the process of scientific inquiry to a pair of commenters who’ve taken issue with the idea that anyone could know anything about the event of abiogenesis — the “Origin of Life”, when the fuzzy boundary between chemicals and life was first breached — that happened on this planet. I’ve agreed with them on a number of points, including Anthony’s main thesis, that there was exactly one way that this universe’s past has unfolded, exactly one “truth” to any event in history, and that as a result, figuring out that exact truth is nearly impossible short of having been there to witness it yourself. He accuses the current scientific establishment of “decadence” (belittling our blog friend DuWayne in the process), and of “ideological materialism” wherein the elite of the scientific world are beholden to assume materialism lest their entire epistemology crumbles beneath them.

Luckily, science doesn’t work that way or we’d have stopped investigating this universe long ago.

The scientific method can be implemented to attempt to model events that it cannot prove with 100% certainty happened in exactly one way. By learning about the past, through the physical and inferential evidence we have available to us, we can develop hypotheses which are testable today. If our hypotheses about the past are correct, we can then correctly predict the results of these experiments, and if the experiments are carefully enough crafted, they can disprove the hypotheses and force us to start over. In the specific case of the abiogenesis event that occurred on this planet, we might never know the exact formula that resulted in our exact lineage. This should not stop us from taking the evidence we have available to us, the direct and inferential physical evidence that shows how this planet was very likely composed chemically in the early pre-biotic environment, and extrapolating from that knowledge that perhaps self-arranging lipids and amino acids might have formed.

The Miller-Urey experiment in 1953 took some of our best guesses about the pre-biotic environment and attempted to verify the Oparin-Haldane hypothesis that it would allow for amino acids to self-arrange. When the experiment was complete, they were proven correct. Amino acids — the building blocks to life itself — formed spontaneously, without direction, in an environment that was like science’s contemporary understanding of the early Earth. If this experiment had failed, it would have put a nail in the coffin of the abiogenesis theory, though not the last one, certainly. The fact that it succeeded suggests one of two things: 1) amino acids might spontaneously emerge in a number of environments, or 2) we got lucky and hit upon the correct way to create amino acids but did not replicate the early Earth, thus disproving abiogenesis. The former is far more likely, for obvious reasons — not ideology, but pure math. If there are a near infinite set of environments that the planet could have had, then there are a near infinite set of environments to test. The problem comes down to one of narrowing — if we know the early Earth had to have ammonia (to provide the organic compounds necessary), then we’ve excised all models that do not include ammonia. Scientists later discovered a photochemical reaction of nitrogen that would provide this ur-Earth with the necessary ammonia. Meanwhile, we narrow our options down significantly with each new piece of evidence.

The fact that better evidence turned up suggesting that the early environment was actually significantly different from the conditions replicated in the Miller-Urey experiment should thus hardly come as a surprise, though the actual early environment is still hotly debated among scientists. Miller tried again in 1983 with the newer data, but came up empty — hardly any amino acids to be found. However, Professor Jeffrey Bada repeated the experiment with an even better approximation of the early environment, e.g. that Miller’s second test had omitted iron and carbonate, and amino acids were once more formed spontaneously through nothing more than pure chemical interactions in the simulated environment. And that certainly isn’t the only such related test.

Two different environments, both resulting in amino acids. Certainly the later test benefits from the extra evidence collected about the early Earth, but getting amino acids in multiple different environments bodes well for our ability to show that every step in the grand staircase toward biology is plausible. We know that the lipid bilayer necessary to create a cell membrane can self-arrange as an emergent property of the lipid’s intrinsic hydrophobia (fear of water) on one side, hydrophilia on the other. They’ll form up all by themselves without prompting, given the right environment. So will RNA nucleotides, meaning if the RNA-world hypothesis is correct, we’re well within our rights to suggest that the hypothesis is the one that best fits the available evidence and make further predictions and experiments from there.

None of this is, you’ll notice, an attempt at building a narrative of “how things definitely happened”. People will often demand such a thing, knowing that they cannot themselves replicate experiment results, nor comprehend their interconnectedness with other such experiments if they’re even aware of these other experiments, nor suss out how all the pieces of the puzzle ultimately fit together. I understand this drive — the drive to build a narrative that is easily digested — because every human being has it. It is that drive that frees up one’s mind to contemplate other things, like immediate survival concerns or reproduction or the pursuit of leisure. It is that drive that one combats when arguing with people who cling tenaciously to their received dogmas. The temptation is great to replace one dogmatic narrative with another. But the scientific worldview demands that we understand that our understanding of this universe may never reach 100% certainty about any single topic or event, but as we slowly polish and chip away at the theories we have built, we can bring them to within impressive degrees of certainty that put any former, more dogmatic, effort at explaining the universe to shame.

The level of certainty that Andrew believes we are expressing about the study of abiogenesis is galling, and his repeated insistence that scientists are engaging in myth-making betrays his lack of understanding of the process. That we don’t know a great many things about the actual abiogenesis event on this planet means nothing, ultimately, in the study of how it might have happened. It is like asking that we know everything about the daily life of the very first ape to climb down out of the trees, or else the theory of evolution is about building a just-so narrative. I’m personally content to allow the process of scientific investigation to grind down all the possibilities until there are but a few left, and we can choose which one fits all the evidence best, until such time that new evidence overturns the model and we are forced to revisit.

That’s how science works, you see. And science does indeed work.

(To within a reasonable degree of confidence.)

How we know things in science, and how we can know things about abiogenesis

How we know all life shares a common origin

According to Anthony McCarthy over at Greg’s blog, extrapolating from this information to determine something about how life began on this planet is purely ideological mythmaking. Never mind that every species on the planet shares the same metabolism, by the same enzymes, which must be coded for by the same combinations of chemicals, and these chemicals must come into being by the same chemical processes. Or that as you work your way backward you can determine the lipids and amino acids that must have been how this particular origin of life happened, and that you can replicate in a laboratory the spontaneous generation of these lipids and amino acids from the pure chemicals in varying environments that are similar to, if not identical to, the best models we have of the composition of the early Earth. Meaning we have pretty much every step in the chain replicated plausibly, so even if we don’t know the exact events, we can with a fairly high degree of confidence claim that we actually know a good deal about how life probably emerged here.

Oh, he also doesn’t believe in emergence, meaning he’s never seen a fractal or snowflake under a microscope. And loves to scoff at the idea that we’re skeptics, just because we’re convinced by the evidence presented. I’ve given up on him, now that he’s decided to “copy [my words] as the most irrational series of assertions by the self-identified champions of science and reason [he’s] had the dubious privilege of reading.”

How we know all life shares a common origin

How strawman arguments and shitty authors undermine #atheism

I haven’t read anything by Anthony DeStefano aside from his anti-atheist screeds on various news journals like USA Today, but I have no doubt merely by looking through the title list that he is a man of deep conviction in that which he cannot see. He’s written a book for children called Little Star, all about how the baby Jesus is very tiny but is our Lord. He’s written a book for grown-up children about how awesome a place Heaven is. And he’s written a book about all those things you can’t see but that the Bible assures you are really really real. And since you know other people believe it, they must really really REALLY be real.

So today we have a Serious Author writing a Serious Article in a Serious Journal about how atheists are superstitious “Materialists” who are simply incapable of comprehending that the parts of this natural world that we haven’t figured out yet are actually impossible to decipher, because God wants it that way.

Of course, it’s not quite fair to say that atheists believe in nothing. They do believe in something — the philosophical theory known as Materialism, which states that the only thing that exists is matter; that all substances and all phenomena in the universe are purely physical.

What nonsense.

We’re off to a running start.
Continue reading “How strawman arguments and shitty authors undermine #atheism”

How strawman arguments and shitty authors undermine #atheism

Scientists investigate ammonia meteorites; science media claims we’re all aliens.

This is a story about meteorites. Well, meteorites, and life. WELL, meteorites, life, and totally misleading headlines.

Pictured: a perfectly normal human wormbaby.
(via some photoshop goon at Worth1000)

I know what you’re thinking. No, this isn’t about the Orgueil meteorite, which in the 19th century caused a ruckus when a conman embedded some grass seeds in it and claimed it proved exobiology. Nor is it about Richard Hoover’s claims, referencing the exact same meteorite, for the third time in his career (first in 2004 then in 2007!). This time around, he’s gaining news traction despite not actually having a discovery. I have precious little to say about it that isn’t already said elsewhere. The Orgueil meteorite is not news, nor is it alien life, no matter how desperately I wish it was.

No, this is, instead, about this science-ish pablum written by the good folks over at The Independent, a UK-based newsish organization. I use the “ish” to denote my skepticism that either adjective fits the subject. In putting together what I can only assume was intended to be a thought-provoking science piece, they’ve succeeded not only in making a mockery of the hunt for life elsewhere in the universe, but also for the hunt for the reasons life exists back at home base. They’ve succeeded also at one more thing, incidentally — in provoking my ire for the unthinking hyperbole that passes for science media these days.

The piece in question begins with the blaring headline: “We’re all aliens… how humans began life in outer space”. Sound like we’re setting up an argument for panspermia, where life itself began elsewhere in the universe and was carried via meteor to Earth by some cosmic happenstance in the projectile ballet we call our cosmos’ set of physics? That’s because other hypotheses have argued for exactly what I’ve described, though they multiply entities unnecessarily and thus Occam’s Razor slices them neatly down to the low probabilities they enjoy presently. And as the rest of the article will soon make clear, they’re not talking about us being aliens at all — only that our constituent components may have extraterrestrial origins. Knowing what we already know about this universe, I have to rebut with: “DUH.” And also: “You’re not an extraterrestrial if you’re born on this planet, asshole.”

The article proceeds from its already rocky start, to making a number of claims that are hardly news and that put the lie to the assertion in the title: the chemicals that make up our planet’s biosphere probably come from outer space.

In fact, a growing body of evidence is now pointing to deep space as the possible source of the raw materials that formed the building blocks of life. The latest study, which focused on a class of meteorites that fell on to the Antarctic ice sheet, also suggests that life’s origins may have been extraterrestrial.

An analysis of the meteorites has revealed that these rocks can be induced, under high pressures and temperatures, to emit nitrogen-containing ammonia, a vital ingredient for the first self-replicating molecules that eventually led to DNA, the molecule at the heart of all life.

Know what else is needed for life? Carbon. Since the only atoms created during the Big Bang were hydrogen and helium, every carbon atom on the planet was built in a star’s supernova billions of years ago. So does that make us “aliens”? Like hell it does. Water probably came from orbital bombardment too — at least, that’s the frontrunner for hypotheses about its origin, but it’d be farly difficult to find the remains of an ice comet billions of years after the fact. The origin of nitrogen, or any other constituent element of the amino acids that are capable of self-arranging and eventually evolving into life as we know it, is certainly an important factor in determining with any level of confidence Earth’s early history.

I will give the scientists a pass. They’re working some pretty detailed experiments that border on the very furthest edge of what we can hope to ascertain about Earth’s early history. They’re not the ones making the odious claims I dislike about the science “reporting” in the Independent. They claimed this:

“What is important is the finding of abundant ammonia. Nitrogen is an indispensable ingredient for the formation of the biopolymers, such as DNA, RNA and proteins, on which life depends, and any theory that tries to explain life’s origin has to account for a supply of ‘usable’ nitrogen,” Professor Pizzarello said. “Therefore, its direct delivery as ammonia and in relatively large amounts from the nearby asteroids could have found a ‘prebiotic venue’ on the early Earth.”

It’s this pullquote that was so obviously mangled not only by the paper’s editor in the ridiculously overinflated headline to pull views, but also by the author of the piece, Steve Connor, in his initial paragraph: “As scientific mysteries go, this is the big one. How did life on Earth begin? Not how did life evolve, but how did it start in the first place? What was the initial spark that lit the fire of evolution?”

He’s describing abiogenesis. While that’s certainly the best theory we have right now, the one that fits all available evidence with the least amount of shoehorning or multiplying entities unnecessarily, that doesn’t mean the people investigating how all this nitrogen got here are even looking sidelong at that aspect of the planet’s history outside the pullquote. Even if abiogenesis wasn’t the accepted theory, there’s every reason to ask “why’s all this nitrogen here to begin with?” It doesn’t have nearly the implications that Connor feels it does, nor that Prof. Pizzarello is quoted as explaining. The galling part about this is, I realize that Pizzarello very likely intended to play science populist in explaining things as he did to Connor. Not every scientist can be their own publicist. Media types evidently have this uncanny knack for pulling the most interesting soundbite from any sentence and blowing the whole story out of all manner of proportion, and I strongly feel the professor was wronged here. I sympathize completely with his excitement, and with his explanation of the implications of his research and why it should continue.

Understanding the nitrogen’s origin, or the origin of any other constituent atom in our biosphere, is a necessary component of any fully formed theory of life’s origins, whether abiogenesis or some other better explanation should one ever come along. It is not, however, a sufficient condition, by any stretch of the imagination. This constant stretching of the truth in science reporting is deplorable in its lack of nuance, and directly leads to much of the mistrust and ill will toward science in general harbored by those people that are burned time and again by the “maybe it’ll cure cancer!” headlines they’re bombarded with daily.

Not every investigation of every phenomenon or historical event is going to unearth the deepest mysteries known to mankind. Sometimes an ammonia-filled meteorite is just an ammonia-filled meteorite.

Scientists investigate ammonia meteorites; science media claims we’re all aliens.

Our first tentative steps onto the shore of the ocean of space

There’s nothing that sparks my imagination with quite the ferocity that space does. And with good reason — in its vastness, we find out so much about ourselves and our origins. It is in space exploration — even if limited to launching more and better probes and building more and better telescopes — that we will find answers to the questions that philosophers have bandied about as purely intellectual exercises since we climbed down from the trees.

Over at BoingBoing, there’s a discussion about Titan’s chemical makeup and eventual fate entitled “A Tale of Two Planets”, where it is noted how similar Titan is to proposed models of Earth’s early history. The fact that complex organic molecules exist there indicates that life could very well already exist as well, or could even start up during the sun’s death throes, should the abiogenesis hypothesis prove true.

On a similar track, Universe Today does a plausibility check on whether sentient life could emerge on planets orbiting red giant stars within their Goldilocks zones, which is interesting considering how sci-fi likes to portray red-giant-based life — as old, wisened, enlightened civilizations given the long time frames they would have had to evolve. The major problem is the very short time frame that a red giant star would have to power a planet’s potential evolution from Titan-like, to Earth-like, so unless these civilizations moved to more distant planets in their solar systems as the sun started to grow, it seems rather unlikely. Red giants are stars in a very late phase of stellar evolution, and generally tend to grow as their fuel is spent and they start fusing heavier elements during their final stages. Knowing that life has taken 3.7 billion years to reach the stage it’s at now here on Earth, that gives us an idea of how quickly sentient life can arise, but the one data point we have doesn’t give us nearly enough information to know whether we’re quick studies or slow learners in that respect.

One thing is for sure, though — we humans are definitely making up for lost time. We recently managed to create and trap antihydrogen, which was a big enough deal. Now we’ve evidently discovered a way to directly detect black holes via the “twist” they give to light that barely escapes it. That means we might actually have a way of obtaining some small shred of information about a black hole outside of the inferential information we get from observing its surroundings. We could create “black hole detectors”, telescopes that are designed to look only for this twisted light and pinpoint where black holes are in our galaxy and beyond.

Another piece of technology with a lot of promise, which was up until recently only science fiction, is the solar sail. Japan’s leading the way in the creation and deployment of real-life solar sails, which turn out to have most of the properties hypothesized. With the ongoing miniaturization of technology, deep space probes will become more feasible, cheaper to produce and easier to use to obtain data about our universe. We will also be able to create probes designed to sit between us and the sun and give us an early warning system for potentially harmful solar flares.

Despite all this new information, amazing insight, and depth and breadth of acquired knowledge, there’s still room in humanity for ridiculous and patently unevidenced “just-so” stories, like that Betelgeuse will go supernova in 2012. Maybe it will, maybe it won’t. If it does, we won’t see the results for another 600 years, though, because it’s 600 light-years away. And since it’s so far away, it certainly won’t destroy the Earth like the crazies seem to think. Nor will the mysterious tenth planet Nibiru crash into us, since there’s no such fucking thing. And besides, Pluto was correctly demoted, so that would make it the 9th planet, jerkwads. Never mind that there’s nothing at all special about the year 2012 anyway, except to a certain class of egocentrics that will probably plague mankind til the end of time.

Speaking of which, when will time end, anyway?

Our first tentative steps onto the shore of the ocean of space

It’s life, Jim, but not as we know it

NASA is due to announce today that they have discovered a form of bacteria living in the arsenic-rich Mono Lake in California. This is slightly old news (e.g. from 2008) mind you.

The bacteria is incredibly novel though — it is apparently capable of thriving by metabolizing arsenate. This is completely unlike any other life form known on the planet. We don’t even yet know if we’re related, in fact. Turns out we’re distant cousins!

Duquesne-based scientist John F.Stolz figured out that the bacteria were able to do this because they contain certain enzymes, or proteins, that act like a key, allowing the chemical reaction to occur.

Bacteria that generate energy by metabolising (reducing) arsenate are already known. But Ronald Oremland and colleagues at the US Geological Survey in Menlo Park, California, were puzzled by the great range of arsenic-eating bacteria. If they evolved recently they must have passed the ability to metabolise arsenic to each other by lateral gene transfer, he says.

Alternatively, arsenic metabolism could have evolved much earlier, giving plenty of time for bacteria to diversify. The newly discovered bacteria from oxygen-free hot springs in Mono Lake, California, support this interpretation. It’s likely that the newly-discovered arsenite photosynthesis, which produces arsenates, opened up niches for these arsenate reducing microbes, the researchers suggest.

This form of life could have derived from a separate biogenesis event. It could have evolved at a very early stage in our planetary biology. Or it could have evolved relatively recently. Regardless of how these bacteria managed to come across this enzymatic ability to eat poison, it ultimately means we can greatly expand the window in which we should be searching for extraterrestrial life — because some life needs only arsenic and sunlight to thrive.

Original study here, though it’s behind a paywall.

Edit: Apparently the novelty is the point of the announcement, not so much the “newly discovered” part. Any evidence that this is a separate biogenesis event will impact heavily the search for extraterrestrial life, insofar as it would prove that abiogenesis can occur in a far vaster range of circumstances than the ones that occurred on our planet. According to the BBC:

Until now, the idea has been that life on Earth must be composed of at least the six elements carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus – no example had ever been found that violates this golden rule of biochemistry.


One idea to shore up these theories is to begin to look for examples of life here on Earth that break the “golden rules” of biochemistry – in effect, finding life that evolved separately from our own lineage.

John Elliott, a leader of the UK’s search for extraterrestrial intelligence, explained how such evidence on Earth could be suggestive about life elsewhere.

“If we can find a ‘second genesis’ on our planet, obviously separate from our own evolution, you could then extrapolate that life can generate multiple times – that it’s not a one-off phenomenon,” he told BBC News.

“And that’s incredible evidence for it happening on other planets.

Edit 2: These bacteria are not from a separate abiogenesis event, sadly. Doesn’t make them any less cool, though. Nor does it mean abiogenesis can’t happen in these circumstances, only that it didn’t happen in Mono Lake.

It’s life, Jim, but not as we know it

Abiogenesis is not spontaneous generation. Period.

During a brief skirmish I had the other day on Twitter with young-Earth creationist Joe Cienkowski (of self-published anti-atheist tract fame), he asserted that the theory of abiogenesis is the same as the now-disproven hypothesis of spontaneous generation. This is, of course, as with pretty well every other assertion about science ever made by Joe, patently false.

Spontaneous generation held that life in its present form today could form from non-life, and did so all the time — for instance, aphids sprang from dew on plants, maggots emerged from rotting meat, and mice were created from wet hay. In 1859, Louis Pasteur performed experiments that put the final nail in the coffin of the hypothesis. He proved definitively that life does not spring, fully formed and unbidden, from any recipe of inorganic or dead organic matter. So the question of the origin of life was reopened for the first time in centuries.

Abiogenesis, on the other hand, does not predict that life in any form known today — not even the simplest single-celled life forms — were created in some flash of magic or through some arcane recipe of components. That would be creation, in the sense of a personal creator deity. Rather, it predicts that, as life is made up of chemical reactions, and the constituent components of life can self-arrange given certain conditions, there is some point in Earth’s early history wherein a chemical chain reaction went runaway and breached the fuzzy barrier between chemistry and biology. All biology is is one single long, unbroken chemical reaction that can be traced back to whatever initial condition sparked it billions of years ago.
Continue reading “Abiogenesis is not spontaneous generation. Period.”

Abiogenesis is not spontaneous generation. Period.

Good evidence for methane-based life on Titan

NASA has released papers based on several readings from Cassini’s recent fly-by of Saturn’s icy moon Titan. Amazingly, there’s strong evidence confirming the hypothesis that there is methane-based, hydrogen-consuming life on the surface, considering the observed chemical makeup matching very closely to several of the necessary conditions for the hypothesis.

One key finding comes from a paper online now in the journal Icarus that shows hydrogen molecules flowing down through Titan’s atmosphere and disappearing at the surface. Another paper online now in the Journal of Geophysical Research maps hydrocarbons on the Titan surface and finds a lack of acetylene.

This lack of acetylene is important because that chemical would likely be the best energy source for a methane-based life on Titan, said Chris McKay, an astrobiologist at NASA Ames Research Center, Moffett Field, Calif., who proposed a set of conditions necessary for this kind of methane-based life on Titan in 2005. One interpretation of the acetylene data is that the hydrocarbon is being consumed as food. But McKay said the flow of hydrogen is even more critical because all of their proposed mechanisms involved the consumption of hydrogen.

“We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth,” McKay said. “If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.”

Cassini is scheduled to make a few more fly-bys, so more data is forthcoming, and I guarantee I’ll be watching for any evidence to confirm or refute this theory. One way or another, we absolutely need to do more research.

There’s a certain parsimony to the thought that life, as rare and wonderful and special as it apparently is in this universe, can arise on a planet with so much difference from our own, and in our back yard. I want there to be life on Titan, desperately, because it gives us more information we can plug into the Drake Equation. It tells us that maybe life ISN’T as rare as we think it is, and that the chemical processes that lead to abiogenesis are not as singular as we might be led to believe otherwise — it’s just that our planet, with its specific conditions, happens to be one type of place where life can flourish and intelligence can emerge over time. That doesn’t make our planet less special; in fact, it makes it more special.

That notwithstanding, I’m well aware that this universe often presents tantalizing hints at amazing possibilities that turn out to be mostly projection on humanity’s part. I will not ascribe this evidence with more portend than it has. There could very well be other natural processes at work that we don’t yet understand, as stated by the scientists in the original article; or even processes that we DO already understand, but are rare, causing the chemical states we’ve observed, without the necessity of life. There could turn out to be not terribly much special about Titan at all, in fact. We mustn’t jump to the conclusion that life exists just because that would be thrilling. Our data could be wrong, or inaccurate, or our conception of certain chemical processes could turn out to need tweaking for a special borderline case that we’d heretofore not discovered.

But a guy can wax rapturous about the possibility, right?

Good evidence for methane-based life on Titan

DNA replication, sans life!

NewScientist reports on experiments that have shown that it is possible for strands of DNA to replicate, without life, near geothermal vents in deep ocean areas. That’s right — DNA replication without life. This is akin to hand-cranking a motor to get it started, then letting it run on its own power thereafter.

In air, particles typically shift into a colder current because they are more likely to be pushed away by warmer, more energetic molecules than those on the cooler, calmer side. The researchers reckon a similar process would occur in the fluid in the vents.

Over time, the DNA templates, polymerase and nucleotides would collect at the bottom of a pore. Once there, they could become concentrated enough for the polymerase to bind new nucleotides to the single-strand DNA templates, replicating the original DNA (see diagram).

To test this theory, Mast and Braun put these ingredients into tubes 1.5 millimetres long. They used a laser to heat one side of the water and create thermal convection. Sure enough, they found that the DNA doubled every 50 seconds (Physical Review Letters, vol 104, p 188102).

“Proving” abiogenesis is just about impossible, this far removed from the event in question. Guessing the exact combination that led to life on our planet might be more difficult than we’d anticipated, because it seems we keep finding plausible methods. The fact is, proving that it is possible in a number of different ways, takes a huge chunk out of the argument that the only possible way that life could have started, is if a personal deity did it through an act of will. Now that we know that abiogenesis is possible via a number of routes, that SHOULD end the argument, but unless we have some sort of ironclad proof for one particular method of abiogenesis, the argument will of course continue. And even if we do have that ironclad proof, it will probably persist regardless, while the God Squad attempts to co-opt abiogenesis as their deity’s mode of creation. That’s just a guess of course; you never know how these developments will really shape future philosophical debate.

Regardless, I’m fascinated by these developments. It gives me hope for our future — or if not our own future, possibly the future of some planet that we intentionally seed via directed panspermia. So long as life continues somewhere and somehow in this universe, I will feel as though there’s still a chance this universe will be understood and all its mysteries plumbed.

DNA replication, sans life!