Archives For panspermia

alien bacteria

One of the topics that’s been prominently featured on Weird Things has been panspermia, the hypothesis that life can originate somewhere in the galaxy and spread though asteroid or comet impacts, or even forward contamination by alien spacecraft. We know that amino acids can form all on their own when certain molecules are irradiated, that some creatures can easily survive a trip though space, and there’s evidence that molecules crucial for life here may have a strong link with primordial impacts. Now, true, the theory has been abused by those who either do not understand what it actually entails, or by those who just refuse to keep up with the science and spend most of their time accusing some secret anti-panspermia cabal trying to keep them down, but overall, it’s quite sound which is why it’s still being kept in mind by astrobiologists. Or so you would think unless you go by a Scientific American blog post which says the following…

In some ways the motivation for proposing this kind of cosmic panspermia is a little dated. It comes from a time when we felt that the origin of life of on Earth was such a mystery, and such an unlikely event, that it was convenient to outsource it. Although this didn’t actually solve the real question of life’s origins, it meant that a specific origin ‘event’ could be extremely rare among the 200 billion stars of the Milky Way yet life would still show up in other places.

These days I think our discoveries about the remarkable abundance and diversity of so-called pre-biotic chemistry [...] in every nook and cranny of our solar system, and even in the proto-stellar nebula of other stars and the wilds of interstellar space – swings the pendulum back to Earth. Nature seems adept at making all the pieces for life, apparently raising the odds of local bio-genesis.

How are these two thoughts connected again? I’m not exactly sure how life being very adaptable would mean that it raises the odds of Earth being its origin because we’re talking about evolution rather than abiogenesis. Caleb Scharf, the scientist who wrote the post, seems to be making the same kind of mistake many creationists do when trying to ridicule evolutionary theory by asking how life would’ve come from non-life and nothing that evolution fails to answer this question. So it’s little wonder that whatever life gets here or starts here would fill every available nook, cranny, and environmental niche since natural selection would favor their reproduction. But whether the origin of these species is on Earth or in space is more or less a toss-up if we’re considering just how well they adapted to their current environments.

Yes, we could say that it’s more likely that life originated on Earth because space is vast and the odds of enough comets and asteroids hitting the planet at just the right conditions for life to take hold are astronomical, literally, so it makes sense to look for an explanation that makes life more likely to arise here. That explanation may not be right, but we don’t have a complete picture of how it came to be and so we’re still trying to find viable ideas that seem to fit the evidence we’ve observed so far. But an important part of the process is not to discard hypotheses without any evidence that they simply don’t fit with the observations, something that Scharf does with an odd certainty about the habitability of promising places in the solar system by hearty microorganisms that should dominate the universe based on the way natural selection works.

But the problem, and the potential paradox, is that if evolved galactic panspermia is real it’ll be capable of living just about everywhere. There should be [organisms] on the Moon, Mars, Europa, Ganymede, Titan, Enceladus, minor planets and cometary nuclei. Every icy nook and cranny in our solar system should be a veritable paradise for these ultra-tough life forms, honed by natural selection to make the most of [the] appalling conditions. So if galactic panspermia exists why haven’t we noticed it yet?

He then goes on to answer his own question by saying that we probably haven’t looked all that hard in all these places, don’t know for what we’re really looking, or possibly both, and ponders would it would mean if we kept searching and found nothing. You can tell that he’s really pushing for the Earth-centric explanation and again, as elaborated above, I can see why, but his primary reason for pushing it seems to be based on a very strange confusion between abiogenesis and natural selection with no facts to back it up. The argument seems to be: we know more extreme organisms on Earth, natural selection seems to be doing it’s job, we haven’t explored all of the promising candidates for life in our solar system in sufficient detail and we don’t really know what we’re trying to find and how we’ll know we found it, therefore, life arose on Earth. Doesn’t seem like a scientific train of thought to me, especially with all the evidence that there was at least an important role being played by organic matter or microorganisms from space…

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Scientific papers and their preprints are used for many different purposes. They can be used to entertain new and strange ideas, generate feedback on a concept before the paper is ready for publication, encourage like- minded collaborators to contact you, and generally, just get your work out into the world. But one use for which they’re definitely not intended, is to serve as soapboxes for one’s whining and conspiracy theories. Chandra Wickramasinghe, who recently gained some notoriety on science blogs for his involvement with an eccentric, publicity-hungry journal which served as one man’s crusade to convince the world that we found alien life, should probably know that. Regardless, he decided to publish a recitation his woes, sprinkled liberally with several conspiracy theories in which astrobiologists are being systematically silenced, on arXiv. If you expect roughly sixteen pages of paranoia and allusions to a sinister scientific cabal censoring research that doesn’t meet some silent consensus the author fervently opposes, you’re not going to be disappointed by his essay, which also tries to to present a few vague findings as irrefutable proof for panspermia events along the way.

Over the decades, there have been a few projects trying to figure out whether life did come from space and it actually is considered to be a viable hypothesis by numerous scientists interested in its many variations. Did life form completely on Earth? Was there some interference with alien bacteria? Could alien bacteria make a trip between the stars and seed our planet? Or did we just get seeded with organic compounds during the solar system’s formation and had the elements to from into RNA and then DNA, kick-starting life? We really don’t know and in the past, the evidence for life coming from space was rather inconclusive and experiments which tried to get some answers but failed to really wow space agencies and universities were shut down so their limited funds could be used to peruse more promising lines of research. But in Wickramasinghe’s mind that’s not at all what happened. Apparently, as he and Sir Fred Hoyle, as well as some other researchers had a few fun ideas at the time, the Sinister Scientific Cabal went to work, covering up the growing proof for aliens seeding our world and rejecting papers with concrete proof that this is exactly what happened. Somehow, he must have missed the last decade of research into whether bacteria can survive atmospheric entry and if tiny organisms known as tardigrades could weather the rigors of space, as well as the search for life on Mars, life that Wickramasinghe insists is being covered up by the agency for reasons that apparently make sense only in his warped, self-focused psyche. To him, astrobiologists are a persecuted minority.

Of course this must be the case because his own astrobiology office was shut down following the disaster that was his work with Schild’s Journal of Cosmology and his publication of awful papers in which the laws of physics and basic logic were turned on their heads to make his hypothesis work. It’s not that he worked with a crank perusing woefully outdated ideas and is decades behind the field, publishing utter nonsense in eccentric vanity journals. No, it must be the machinations of the aforementioned SSC suppressing evidence for extraterrestrial microbacteria, alien viruses, and fossilized remains of creatures from other worlds found in meteorites held by NASA. Keep in mind that this is the same cabal which allowed NASA scientists to publish a highly inconclusive paper arguing for the possibility of arsenic-based life, and let researchers note that a rock impregnated with bacteria and carried by Columbia survived reentry and the craft’s disintegration, which they took as evidence for the notion of microbes arriving on other worlds intact. It’s almost as if the only kind of research that the Cabal  is censoring is Wickramasinghe’s ramblings and his pet projects, which either rush to conclusions based on lackluster evidence, or make grandiose and ridiculous claims based solely on other grandiose and ridiculous claims. Now if he were a scientist, he might start wondering if his work is lacking a little rigor and if he were to try something different, he might have a paper worth publishing in a journal which doesn’t outsource its site design to someone who’s never seen the web past the late 1990s.

Unfortunately, Wickramasinghe has turned into a crackpot, and his reaction is to cry persecution and proceed to very loudly defend himself from his perceived enemies, who are apparently just plotting to take him and his work down from the shadows, as per the textbook behavior of a crank in the final stage of his affliction. It’s ridiculous to argue that today, the topics of panspermia and alien life are somehow taboo because NASA has a whole lot invested in hunting for aliens and looking for habitable worlds. In fact, the vast majority of its space exploration budget is used for some form of alien hunting, and that’s not to mention that SETI is regarded not as a collection of random kooks who think they’re going to talk to aliens, but a perfectly respectable scientific organization which is pursuing a very difficult but scientifically justifiable goal. Just because you don’t get your day in the sun for recycling ideas you concocted with a man who had a track record of being spectacularly and demonstrably wrong about almost everything outside of astronomy to such a degree that a fallacy often cited by creationists bears his name, doesn’t mean that you’re a victim of a conspiracy. It just means that you’re an old geezer who hasn’t had an original idea since the 1980s, and you’re furious that scientists have moved on and won’t let you ride on Hoyle’s coattails anymore, much less coast on your own recycled half-guesses.

[ illustration by Aaron Sims ]

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Normally, when it comes to the concept of panspermia, I’d like to call myself open-minded. Having alien bugs or bacteria travel across space and landing on potentially habitable worlds isn’t nearly as far fetched as it may seem according to a number of studies and experiments. Additionally, we’ve known for a long time that all the comets and meteors that hit our planet on a regular basis during its youth were the closest thing to chemistry kits for kick starting life, delivering water, amino acids and organic compounds with every impact. So the idea is scientifically sound, but one attempt at advocating it almost made me do a spit take across my keyboard as potentially great science was drowned out by a statement that goes against all known biology and physics.

primordial moon

The news editor at Cosmic Ancestry was doing a little write-up about the puzzling discovery of seemingly old galaxies in distant space. Since looking into the depths of space is also like looking back in time, this would mean that the galaxies aged prematurely. This is certainly an interesting anomaly that needs to be explained, but it’s hard to see the link between these results and the origin of life. And this is when this little gem reared its ugly head, mixing creationism and pseudoscience in a manner worthy of Answers in Genesis…

Most darwinists know little about the big bang, but rely on it to mandate that life must originate. In cosmic ancestry life never originates and must come from the infinite past.

Wait, what?! We have to throw out modern cosmology to accommodate panspermia? Since when? And aren’t we left with the same infinite reductionism problem we find in religion? Life had to come from somewhere, so just pushing it back to the ancient past and ignoring what the other sciences have to say about the universe to make it plausible, doesn’t work. Wasn’t the whole point that life gets started on one planet and eventually, due to chance, cross-pollinates other worlds and the evolution takes off in its new home? And speaking of that, do we really need to invoke an anti-evolution epithet favored by creationists? Isn’t alien life hitchhiking from world to world supposed to evolve in its new home, not just arrive as a pre-assembled ecosphere?

Here’s the bottom line. Panspermia can’t be the answer to the origin of life in general. It can explain how living things arose on a particular planet and is at best, an intriguing and potentially profound part of a much bigger puzzle. Whether it got there through incredibly tough microorganisms that made it to other worlds by everyday events, or as forward contamination by alien explorers surveying potentially habitable worlds, it will never give us the ultimate answer of how life arose. We can only find out with biochemical experiments and research. To use alien bacteria as the ultimate answer to the biggest question of biology is a religious tenant, not a serious scientific statement by any stretch of the imagination.

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young earth

Just because Darwin wouldn’t discuss the origin of life in his work, doesn’t mean he didn’t have an opinion on the matter. And that opinion is actually pretty close to modern scientific thinking, that living things are products of chemistry rather than something requiring divine intervention. A recent paper cataloguing Darwin’s notes on the subject and correspondences with scientists and critics probably won’t be a big surprise to those familiar with his work. However, there’s one very interesting tidbit that caught my attention. It seems that the naturalist may have been exposed to the concept of panspermia, the idea that living things could cross space and seed young worlds where the newly landed aliens can spring up if the conditions are just right for their survival…

In his recently published Charles Darwin, Shorter Publications 1829–1883, van Wyhe (2009) has included a curious item published in 1881 in [the journal] Science under the title Mr. Darwin on Dr. Hahn’s discovery of fossil organisms in meteorites.

The note describes an exchange between Charles Darwin and Otto Hahn, an amateur geologist who claimed in 1880 that he had discovered [the] remains of extraterrestrial sponges, corals and plants in the Knyahinya meteorite that fell in Hungary on June 6, 1866 (van Wyhe 2009).

Apparently, Hahn even showed Darwin the fossils in question and made quite an impression. However, while he was generally supportive of the idea, the naturalist never outright confirmed or denied it. Considering that he wasn’t one to jump to conclusions, it’s likely that he never quite made up his mind on the subject and only entertained the possibility as curious but in need of further review and additional confirmation. Other scientists of the day also shared his enthusiasm, though for reasons we would find erroneous today.

Because of William Thomson’s (later Lord Kelvin) claim that the Earth’s age was too young to be compatible with Darwin’s theory of evolution, and [Louis] Pasteur’s work debunking spontaneous generation, the “cosmozoa/panspermia” theory was championed by many noted scientists during Darwin’s time, although apparently he never commented on the concept. The idea that there were fossils present in some meteorites was embraced by parts of the scientific community although others questioned the validity of these claims.

Of course Thomson’s estimate of 20 to 400 million years was way off and theoretically, our planet was around long enough for life to slowly develop and diversify without the need for spontaneous generation or a seeding from extraterrestrial sources. However, we also know that meteorites not only have a full collection of the kinds of amino acids life as we know it needs, they also have a bias towards left handed chirality just like all living things on Earth. We also know that some simple animals and bacteria can survive the strain of space travel, provided they’re put into a kind of biological stasis first. So while the evidence for panspermia or any potential extraterrestrial involvement in our biosphere is rather tenuous, it’s still there on the fringes and it’s hard to rule it out completely. Though, to be perfectly fair, I would have to say that Hahn’s meteorite could very easily be a case of mistaken identification and its evidence is very much in the eye of the beholder, kind of like ALH 84001 and its microscopic contents that look like fossils to some panspermia enthusiasts.

See: Peretó, J., Bada, J., & Lazcano, A. (2009). Charles Darwin and the Origin of Life Origins of Life and Evolution of Biospheres, 39 (5), 395-406 DOI: 10.1007/s11084-009-9172-7

[ digital matte painting by Inga Nielsen ]

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wet mars

We all know about the SETI project which listens for potential signals from aliens with radio transmitters and powerful lasers. But now there’s a new acronym to memorize in the search for otherworldly life: SETG. It stands for the Search for Extra-Terrestrial Genomes and its lead scientists want to do nothing less than find and sequence gene segments of microorganisms living under the surface of Mars. How? They’re betting that Mars and Earth share an evolutionary heritage and that will allow biologists to read Martian DNA.

Let’s rewind to the beginning. Around 4.5 billion years ago, when the planets were just forming and fusing into the solar system we see today, asteroids and comets rich with organic material rained down on the young planets and helped jump start life. As the collisions continued, some of this new life was exchanged between Earth and Mars and hence, by trying to analyze the 16S ribosomal RNA gene which is often used to identify bacteria and their evolutionary lineage, the project would not only prove that there’s recent Martian life, it would also provide evidence that life in our solar system, and indeed the universe at large, may be related. Or at least, this is the theory behind SETG’s plans.

Suppose that a Martian rover a few decades into the future carries a SETG machine which uses solvents and a special dye that glows when it binds to genetic materials. What kind of life could it find? To get a reading, the alien microbes would have to be no older than 1 million years old, the average time it takes for the DNA molecule to decay, use amino acids we know of and have colonies large enough to leave an identifiable trace in the sample. Oh and they would also need to be different enough that we call tell them apart from any possible Earth bacteria which could hitch a ride to the Red Planet and contaminate the results. And that’s where issues like chirality and the distribution of basic compounds for life make create a huge problem for alien hunters.

In a previous post, I examined a NASA study which shows that asteroids rich with water tend to produce a bias towards left-handed chirality, or when the molecular structures of amino acids used by every known organism wind to the left. A right-handed chirality in alien life forms is an exciting possibility and a sure-fire way to know we’re dealing with organisms that are definitely not like any living things we know of, but it has a lower chance of fostering a biosphere than the left-handed amino acids overrepresented in the very same asteroids crucial to SETG’s research and experiments. If we do find Martians to run through a sequencer, we may find that they and their Earthling counterparts are too closely related for a definitive identification. But of course, we have to find those elusive alien microbes first…

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aliens and you

October 14, 2008 — 4 Comments

Panspermia is the only biological term I can think of which sounds more like a title of a high concept porn flick with a sci-fi theme. But behind the odd name lies a curious concept that if proven true, could mean that we have common ancestors not just in the deep past but on strange worlds across the cosmos. If some species of bacteria somehow seeded millions of worlds, it may have evolved into other creatures on other planets while staying unchanged on its home world as a living fossil. Of course that mysterious “some how” is what makes many scientists think twice about the viability of panspermia.

The odds of a big enough asteroid slamming into a planet with organisms that can survive an unprotected spaceflight like Earth’s tardigrades, launching them towards a solar system tens or even hundreds of light years away at just the right angle and at just the right quantity to get to a planet where these organisms can thaw and start evolving are, well staggering. This is why most scientists today note that panspermia is a curious concept, that would be incredibly exciting if true, but think that life most likely appears on a planet which can support it with a solvent and an energy source (i.e. food and water).

However, recent experiments which launched tough creatures from our own world into space and safely brought them back, the case of Earth bacteria surviving on the Moon and numerous complaints from NASA engineers about how hard it is to sterilize equipment and avoid almost inevitable contamination of other worlds with Earth germs got me thinking. If life is billions of years old and we think that the oldest planets we can hypothesize of are more than twice as old as the Earth, could there have been in all the vastness of space other civilizations sending a few probes carrying tough organisms from their planets into deep space and seeding worlds as they go? Having a sort of intelligent dispersion of life would guarantee that the bacteria will get to a planet or a moon and as it would make sense to send probes to look for alien life, all these probes are highly likely to be sent to worlds more or less hospitable to living things.

groveback

If that sounds like an even bigger stretch than random meteor impacts, consider what we want to do in the next thousand years. We want to change Mars to be more like Earth. We want to go and explore habitable environments in our solar system with contaminated probes. We want to send robotic explorers to other planets to find alien life and those explorers will also carry our germs among the stars. Could we eventually be responsible for panspermia events when our technology becomes advanced enough to freely move around space? Maybe life in the universe could be a combination of organic components coming together in the right environments, natural seeding and intelligent dispersal of a space faring species that just cant clean its space probes well enough? Certainly something to ponder when we explore the cosmos

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In early September, a small batch of tiny invertebrates called tardigrades (or water bears) was launched into space without any protection. The tiny creatures survived, came back safely and continued to breed normally, with no notable radiation damage. So what’s their secret? Theyre anhydrobiotic organisms, living things that evolved to survive extreme droughts by entering a state of suspended animation and repairing their DNA when its damaged by a lack of water.

water bear

Deep inside their cells are pristine DNA fragments that can be used to replace or fix a damaged section of its genome through a process known as annealing. (read a very detailed explanation of how it works) This ability is so unique, its been proposed that anhydrobiotic creatures came from outer space and are proof of panspermia. Its an even more tempting proposition when we consider the fact that we are too complex and too big to have such an ability. The extreme conditions that require extreme adaptations aren’t conductive to complex, macro-organisms. Theyd die before they would be able to develop enough structure and complexity.

So could a colony of alien creatures related to water bears and super-tough bacteria evolve on another world, get blasted into space by an explosion, survive the millions of years it takes to travel to another planet and help spark life on this one? How about putting this idea to the test by blasting water bears to Mars and checking up on them with one of the rover missions there? How expensive could it be to blast a piece of rock to Mars and how much could we learn?

[ micrograph courtesy of Goldman Labs ]

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