Thought you might enjoy the content.
“WHO ARE THEY?
Genomes.
They get around on planet Earth.
You, dear friend, share fifty percent of your DNA with—yes—a banana.
While some folk were offended at the notion we might share genetic heritage with a chimpanzee—we do. And with his favorite yellow treat.
adenine (A), cytosine (C), guanine (G), and thymine (T) are nucleic acids that make up your DNA. And a banana’s.And the chimp’s.
It’s half the DNA spiral ladder..From Science Primer: Like DNA, RNA polymers are made up of chains of nucleotides *. These nucleotides have three parts: 1) a five carbon ribose sugar, 2) a phosphate molecule and 3) one of four nitrogenous bases: adenine, guanine, cytosine or uracil…don’t freak: I’m about to speak English.
Once cells ‘learned’ to reproduce themselves, life was off and running. And Earth’s genetic heritage is connected: dinosaur genes aren’t totally gone. We likely have some things in common—after all, they had hearts, livers, lungs, and other structures resembling us more than either of us resembles bananas.
The next question is—what other assemblage of chemicals would be self-reproducing, and carry information to organize a living body of some sort, change moderately over time, and derive materials from the environment?
How easily do these acids form in the environment? How easily do they associate? And how hardy are they?
I wouldn’t be that surprised to find, if we find evidence of Martian life, we find evidence of RNA-DNA chemistry…some of Mars may have landed on us, and they had a head start in cooling. I have more question regarding, say, Titan. Will we find a second viable system of doing genetic business?
Nitrogen, carbon, phosphorus, etc: the elements are the elements. The relative availablity varies from star to star, but the elements themselves are the elements, and certain ones combine easily and certain ones don’t combine without heating and pressure. Chemistry is chemistry. Some sugars, eg, wind left-handed and some right-. But basically, sugars are carbon, hydrogen, oxygen—water is hydrogen and oxygen…all pretty low on the periodic totempole.
Just sayin’. IANAC—I am not a chemist, nor a biochemist, but seems to me that given the same building blocks, similar heat and pressure, it may be a duplicatable result.”
These days, the chimpanzee’s company might be preferable!
(Still wrapping my head around the effusively amorous and peaceful bonobos, and what that implies about human religious notions regarding sexuality, because I grew up feeling so restricted and conflicted about it. The bonobos don’t mind. Cats and dogs don’t mind. Why then do we humans get so hung up on it? Or, why was it such a problem for me, or my social environment, growing up and (less so but still so) now?)
That aside — It’s fascinating that we are only around 2% different from (other) great apes, and less than 2% genetic difference between any humans, with some evidence that there was a genetic bottleneck which reduced human genetic diversity in prehistory. So that there were multiple ape-man-like species up to and alongside our own species, until humans became the survivors. In other words, we are just one kind of anthropoid. A little nudge here and there, and Neanderthals or some other species might have won out.
One recent special (documentary) surprised me with the differences in growth rates for Neanderthals. They had a brief example of a Neanderthal boy, around nine or ten, already adolescent because that’s how Neanderthals were, a quicker, shorter life cycle, and a different rate than human childhood and adolescence and adulthood. The same special discussed a few other hominid species’ life cycles and brain capacities.
Lucy, one kind of Australopithecine, was somewhere in the middle between chimpanzee level intelligence and our own. This would have made it hard to say if her species were therefore “sapient/sentient” intelligent species, or not. — Possibly, we need a “semi-” or “proto-” category? — What would we do if we encountered that? What if it arises in future? The process is ongoing, and some ape or monkey out there might be a different kind of Adam or Eve, right? (Or some other good candidates for intelligent lifeforms, not all of which are primates, or mammals, or land-based.)
Dolphins and whales — You know, if we want to be able to understand future alien lifeforms’ communications, it strikes me that we need to be able to decipher what dolphins and whales are communicating. Oh, sure, some of it is just echolocation, bio-sonar, a map of their surroundings for navigation and locating food and potential threats from predators. But some is likely other information. How much, if any, is what we’d call “speech,” intelligent communication of ideas and information? Who knows, but it’s certain they are communicating some kind of info, a whole lot of it in a highly complex fashion, enough that intelligent speech seems like a real possibility. It would sure be something if we could figure out what they’re saying and be able to join the conversation. — Aside: How in the world would we annotate that in writing or musical notation? Wow, what a challenge to everything we know about music and language.
Hmm…that banana. Unlike Dr. Zira, I like bananas and need to get some when I go to the store. Hah. — How much like a banana or a tree or a mushroom or a slime-mold are we? (Yes, kingdom Plantae and kingdom Fungi, plus whatever other multicellular kingdoms, if any, have been added / changed since I had college biology I and II.) — How very alien are plants and fungi from us, and yet they are Earth life too, and related, distantly. Octopi and cuttlefish, and insects and spiders, are weirdly alien too, and yet they are closer to us genetically than plants and fungi; they’re invertebrate Animalia.
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More speculative: If I understand right, Earth life’s RNA and DNA have spirals going one way, but the other way is about equally possible. So why don’t we see examples of it here on Earth? Or who’s to say we wouldn’t find it going the other way on some other planet or moon? (Titan, Europa, etc., or maybe Mars, fossilized or extant living forms, somewhere around ice or underground water?)
But are other forms possible? Silicon has been put forward as a possibility, as in the Horta or in Alan Dean Foster’s “Nor Crystal Tears,” both from older scientific speculation. What else might be, quite literally, “viable,” (livable, workable)?
If we do find life elsewhere, which seems a lot more likely these days, beyond the single-celled level, into complex organisms, what will that be like? There’s a good chance it won’t have a humanoid form. It could be all kinds of things. It could well be something we’ve never seen or thought of on Earth.
For that matter, would we recognize immediately if something is a life form, or if it’s intelligent? Would it be so alien that ewe’d have trouble recognizing it as life or as intelligent? Would aliens have just as much trouble recognizing us as intelligent life forms? (Hmm, given how humans sometimes behave, possibly “intelligent” is more like hubris.) Would we be able to communicate, or would we be so different in how communication was transmitted and perceived that it would be nearly mutually unintelligible? Or would we (likely) need computer synthesizers and processors so the human translator, or ordinary people, could talk to the aliens, and aliens could talk to us?
I’d imagine that even parrots or other birds, as well as dolphins and whales, could produce sounds so differently and so complexly that their understanding of us and our understanding of them, to whatever degree they have intelligence, would be very complex. (My guess would put dolphins and whales over into likely intelligent, and parrots and ravens and such into photo- or semi-.
I wish I knew which documentary series t was that had covered some of the Pre-Cambrian and Cambrian eras, with some truly weird early lifeforms, some of which had neither radial nor bilateral symmetry, just really odd. I’d love to see that series again. It was on cable in the 90’s or early 200’s, 90”s, I think.
What we’re getting showing planets are common around stars and how at least one or two moons of Jupiter and Saturn might be good places to look for life, besides Mars, is really exciting.
From what I’ve seen on exoplanets, there are a lot of “also-ran” planets that aren’t quite hospitable to Earth life. But what we (the public) are seeing is also that life could be common in the galaxy, and planets and mons are very common.
Both “alien invasion” and “asteroid impact” are so low enough in probability, and so high in, “if it happens, I by myself couldn’t stop it,” that it’s not a worry. And for alien contact, I would rather hope that any aliens technologically advanced enough to get to Earth would be beings we could find some way to communicate and deal with. I like trade of goods and services and ideas and imagination, better than doom-and-gloom and being enslaved or wiped out or, uh, eaten. Or plugged into some weird Marix or Borg hive, for instance. I am for being prepared, but I think anything that reaches us would have us so outclassed, it would be like mosquitos or primitives with sticks and stones. Be it noted, both mosquitos and supposed primitives can be quite effective in defending themselves, as a broad population.
And to the invasion point, there’s another counter-point: The Norman Conquest didn’t go quite like the Norman French expected. The Anglo-Saxons and the Norman French ended up merging, in England, a very rare thing. (Latinized Gaul and Britain might be others, and Frankish Northmen becoming French. And Viking raiders who were also absorbed into England.) Goths and Celts…come to think of it, merger, a blending to some degree, is not so uncommon after all. — So possibly that “alien invasion” trope needs to be re-examined.
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Noe: “The Expanse” season 2 is supposed to start tonight. One heckuva cliffhanger from season 1, so we’ll see how they make it.
Also Note: Good progress on a new font idea, getting it into my font-editing program. It feels *great* to get back into this!
Your 2% difference between us and the Great Apes is about the same as the percentage of Neanterthal genome that can be found in non-Africans. But different people have different two percents, so combined it’s estimated about 40% of the Neanderthal genome exists today in the world. Not forgetting that even back then we shared a “Homo” genome.
The sixty-plus year old Miller-Urey experiment and similar ones showed that the building blocks of life easily and spontaneously form in or on primordial Earth:
https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment
At some point in the cooling of Earth, rain starts to fall onto hot rocks–probably at night on the poles, first–and gradually every square nanometer of Earth spends untold nanoseconds of time at Goldilocks temperatures, as do untold cubic nanometers under water, in sand, between rocks. The number of simultaneous chances to form a self-reproducing nucleic acid chain are quite astronomical. Whether the nucleic acid was DNA or RNA or “XNA” we’ll probably never be able to determine since simulating or reproducing the experiment requires too large a computer or laboratory to be practical.
The earliest life formed pretty much as soon as the Earth was cool enough, supporting this optimistic view. Abiogenesis. While XNA from Mars might have helped, it might not even matter. The trite biology definition of life–the three Fs: Feeding, Fighting, and Reproduction–don’t really come into play. Food is all around. The first self-reproducing XNA has no competition. Reproduction is the only thing that first self-reproducer does or can do, except…
…It can make mistakes reproducing. It can mutate. Evolution is off to the races. Anything can happen. Anything does.
Even so, it takes around three billion years for multicellular life to form. That’s difficult. Everything else is pretty easy.
Intelligent life is everywhere: cats, dogs, bonobos, dolphins, parrots, crows, octopuses (get some backbone, guys!) It is even rumored to exist among some hu-mons, but this claim seems more than a little dubious at times.
Use of tools is also pretty widespread: crows, seals, primates. A few species can imitate tools they only see, which is the seed of a technological culture. We have only one known example of a technological culture, but dinosaurs could have been in the Wood Age–maybe even the more advanced monument-building ages archeologists are prejudiced toward–and no evidence could be left to discover, even if we decided to actually look for it.
https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life
Octopods are supposed to be very intelligent, good at problem solving, etc. What would they be like if they evolved to the point of being able to travel in space? They have copper based blood, three hearts, and a two-tiered nervous system (the arms can act purposefully independently of the brain) Would they have to evolve to the point where they could leave the water and exist on land in order to become spacefaring? Would their language be visual? Would it be augmented by sounds? How would their reproductive strategy translate into culture? What form would “durable communication” take? (ours takes the form of making symbolic marks on some sort of durable substance like stone, clay, paper, etc., and once that symbolic threshold is crossed, every human culture seems to take that route.) What effect would octolateralsymmetry have on their thoughts and language (versus our bilateral symmetry)? Been trying to get my head around something like that . . . .
CJ, one thing that has always struck me about your “family ship” cultures such as in the Alliance-Union universe is how biologically logical it is, especially from the genetic standpoint to “out cross” the way they do on “shore leave”. We humans have a cultural repertoire to draw from and the “family ships” are a direct analog of the small, traveling family bands of hunter/gatherer cultures. I enjoy the juxtaposition of that lifestyle against the “settled farmer/nuclear family/city-state” lifestyle of the stations and I like the way you compare and contrast the “morals and mores” and the mindsets of the two cultural strategies.
Octopoids and cuttlefish (related) have a mix of radial symmetry (the arms and some other anatomy) and bilateral symmetry, but thinking about it as octolateral symmetry works about as well. In college intro biology, circa 1984 or 1985, we got that cephalopod were possibly closer relatives of vertebrates, but had taken a different track. Early on in embryonic stages, there are important similarities, and somehow, they move toward radial symmetry more than bilateral, while vertebrates move toward strictly bilateral symmetry. As the Cephalopoda mature, they move toward radial symmetry, and the bilateral and radial are a variation on the same symmetry theme. There are some other weird variations in other invertebrates besides.
I never properly memorized the Crebs cycle and other ATP and muscle-oxygen cycles in intro bio. I really liked the genetics unit, but we didn’t spend much time on it. I got mixed up on the exam on ACGT and a few other questions, test anxiety. Already by then, I was having trouble due to, hey, I’m gay, but I wasn’t accepting it, was having a bad time dealing with it (was overcompensating with religious life too, which wasn’t helping that). So I was already getting myself into a mess in academic terms when I should have otherwise been able to study fine. I can see now, I was already getting test anxiety and so on, when I should have been fine.
Octopi have been known to travel short distances out of water to get from one ocean pool to another, say. There have also been cases where they were clever enough to escape a tank (aquarium) and go a-wand’ring, walkabout. If some lucky octopus were to get a few mutations for amphibious life, for lungs, say, and better adapted skin surface, then they’d only have to get back in the water for spawning. or they could develop a way around that too, or mutate further into a terrestrial mode. Land Octopi?
Add to the tool-users list, otters, both sea-going and freshwater.
I would be surprised if some clever raccoons didn’t figure out tool using at some point. With or without any genius mutations. I’m told they can open cabinet doors (so can cats). Not sure if raccoons can open *latched* doors. But it seems like they could be smart enough to master some tool use. Maybe it would take a “super-genius” raccoon to figure it out and pass on his/her genes and teach the little nippers, but it seems a possibility.
Life keeps evolving, even while we sit, or while our technological rate goes skyrocketing. All it takes is one or two important mutations to be passed on, and you have a new trait in a species-branch, an offshoot. A few more, and you get a new species, relatively speaking. So what shows up in all the mammals and birds out there that wasn’t there before? What appears in invertebrates? There could be major ew branches in life, if something happens in some wildly new way.
Pacific Northwest tree octopus! CJ, have you or Jane ever encountered them? 😀
http://www.snopes.com/photos/animals/treeoctopus.asp
The Pacific Northwest tree octopus is an Internet hoax created in 1998 by Lyle Zapato.[1] This fictitious endangered species of cephalopod was given the Latin name “Octopus paxarbolis” (the species name being coined from Latin pax, the root of Pacific, and Spanish arbol meaning “tree”). It was purportedly able to live both on land and in water, and was said to live in the Olympic National Forest and nearby rivers, spawning in water where its eggs are laid. Its major predator was said to be the Sasquatch.
The Pacific Northwest tree octopus website is among a number of sites commonly used in Internet literacy classes in schools, although it was not created for that purpose. Despite the falsehoods shown on the site, such as the inclusion of other hoax species and organizations (mixed with links to pages about real species and organizations), all 25 seventh-grade students involved in one well-publicized test believed the content.
^quoted from Wikipedea.
I wonder how many adults, 18 to 75, say, with and without any post-secondary education, would also believe it. Or, what about a timed study of the individuals and group, to see how long it took anyone to perceive it was false, a hoax, and then to persuade others, as well as for others to come to the conclusion independently. I’d bet the results would prove very interesting, especially the dynamics of it.
I’d also think that a high percentage of adults might respond essentially the same as the 7th graders. I know literacy and critical thinking are still deeloping at that age, but many either are already near adult levels or never get too much above their early adolescent feels — do they? I remember being appalled at reading level figures, the last time I saw them, but then, I was reading adult-level books early on, like most college-bound kids, and my language skills measure very high on standardized tests, which I would expect is usual for language majors. So my perception of what should be there is biased higher than the average US levels.
For completeness, you’d also need to look at 8th graders and high school students, to see how or if they catch the tree octopus.
I would expect no mention of snip hunts or drop bears to its results beforehand. 🙂
I see despite a new computer and keyboard, I’m still having typo issues, or just plain, the brain and fingers do not coincide: brain’s racing ahead of fingers, usually.
“their early adolescent levels” – not “feels.” (Though emotional maturity is probably much the same too.)
Biology is so weird and wonderful already, it’s no wonder someone who isn’t very well read in it would believe one more very strange creature (though references to Sasquatch should give the game away to anyone who’s heard anything about that!).
There are several kinds of fish that can survive out of water for a while, and even move around, like the young eels that migrate through wet grass to cross the dikes and get to the ocean here in Holland; so why wouldn’t an octopus-species be able to evolve further in that direction? The octopus escaping from the aquarium seems to say they’ve got a tiny bit of what’s necessary to start a capacity for living in air already…
It’s good to teach people to be a bit sceptical, but being too sceptical would mean you won’t believe a lot of what’s really true either. Who would believe a flower that blooms underground? But the lady who posted it is a biology teacher, who found it in a biology textbook, and I believe it and marvel at the wonderfulness of nature.
It would be a pity to lose that marvel to excess scepticism, but teaching people who aren’t internet- or news-savvy how to find the right balance in that looks quite difficult to me. Not every hoax site (or false news/propaganda site) signals itself so clearly by referencing Sasquatch.
@Hanneke, I think your initial premise is very apt. Many people, for their own internal reasons, want so desparately to believe “anything is possible”, that it becomes an article of faith. Then it morphs into, “I don’t know this is impossible, therefore it is possible.” I think many (if not most?) Americans take a back seat to no one in this.
WOT?!? Sasquatch isn’t real? Say it isn’t so! 😀
Actually, my human anthropology prof, Grover Krantz…one of the best teachers I ever had…is, to me, a good example of how the scientific mind should work. He was one of the experts who popularized the idea that the sasquatch tales could have their origins in reality. Gigantopithecus, (I prolly spelled that wrong) was a very real branch of human evolution and the sasquatch tales correspond to the area of known occupation. That G-cus coexisted with Neanderthal or Homo-us long enough to seed the “myth” is not a stretch. That G-cus survived into modern times in secluded areas was also not a stretch. Are hoaxes a dime a dozen? Oh, yes. But his attitude was there’s enough “possible” there to make it INTERESTING and FUN to look into.
(gosh…give us control i, will you?)
I guess what I’m trying to say is…yes, there are those who will claim anything is possible because, in part, they’re simply overwhelmed by the input, founded, blatantly crazy, and well-perpetrated hoax, that rather than try to sort it all out, they fall back on faith and just try to get through the day and pay the bills. Sometimes they become absolutist and grating in defense of their confusion, but that doesn’t mean they’re stupid. I still look to an educational system that teaches memorizing names, dates, and other absolutes, rather than emphasizing causality and logic, but that’s just me. (Grover also had a policy that even if you gave a “wrong” answer on a test, if you supported your answer, you could get credit, provided your support was well-founded.)
(There’s a reason I’ve stayed of the interwebs the last year, and it’s name is politics with has filled the web with all the above.)
Anyway…others “accept” sasquatch just cuz it’s fun. Some “accept” FTL for the same reasons. Years ago, black holes were “scientifically” impossible. Dark matter was a joke. Sometimes someone’s “fun” is the future’s reality…because they were willing to take the risk of ridicule.
It’s no news to any of us that, all too often, scientists are blinded by their own convictions of what’s possible. Science Fiction lives for the “what ifs.” And thank any god you care to invoke that some of those what ifs spark the imaginations of the folks who can make those fantasies come true.
ARGH…back into my black hole.
@Jane: “rather than try to sort it all out, they fall back on faith” That I would call reprehensible intellectual laziness, but to be sure there are certain levels it takes “skull-sweat” and intellectual capacity. (I remember working through understanding General and Special Relativity in college physics.) But beyond that, believing the Scientific Method and rationality are the paths to real world truth is a “faith”. It get back to that epistemology.
“all too often, scientists are blinded by their own convictions of what’s possible.” Certainly we all make mistakes, and can get caught up in prejudices. The Scientific Method is error correcting by nature. But most of the time scientists are pretty intellectually honest–they/we are trained to be, and we’ve got examples of how scientists have gone wrong in the past.
We know we don’t know it all, that what we think we know will likely be revised, e.g. Newton & Einstein. Nobody has yet compromised the Laws of Thermodynamics. It’s not hubris to believe them. Certainty is the province of religion, not of Science.
And that, Dear Readers, is why I linked to the Snopes site for my article about the PNTO.
Ah, one of my favorite critters. Or non-critters.
(I sent the URL for that to one of my aunts, who is an experienced scuba diver and wrote a book about watching critters while diving. Including octopodes.)
Oh, man. Had no idea of the “tree octopus” thing when I wrote what I wrote. Hahahah. An amphibious octopus would be a big deal, though.
Huh, you know, snipe hunts, I always envisioned some sort of a bird or small mammal. Imagine going on a snipe hunt and bagging a tree octopus! Heheheh.
Oh heck, I can’t remember the Australian version. Is it a drop bear?
Ah but the cryptid I’ve always loved is the house hippo. (Apparently a much broader range than the tree octopus). Its too bad they don’t actually exist as it would give me so many good excuses about the state of the (non)housekeeping.
Ah, so you’re a proponent of the old song, “I want a hippopotamus for Christmas!” ;D
There’s always that meteorological phenomenon, the interior domestic whirlwind.
And then there’s whatever creature / event steals socks (etc.) from the washer and dryer. Stealing an item or two from the washer was a new thing. One never knows. Perhaps some house-elf needed warm feet.
And, please, people, it’s “Kefalopod” not “Sefalopod”! It’s from the Greek for “head”, from which “cap”, “capitol”, etc., also derive.
REALLY? I always thought it was Cephalopod. Shows you what I know. I always thought it was something about a headed-foot or footed-head. Doesn’t “pod” mean foot?
Hmmm…Firefox spellcheck doesn’t like any of them. HELP!
Sorry…back into my black hole. Cool discussion everybody!
Ka-ko-ku-se-si is the Dutch rule for pronouncing the letter C: pronounciation is determined by the following vowel. From a curious cacophony to cells with cilia, English appears to follow the same rule, which is why most people call a cephalopod a sefalopod, even though the Greek word for head is kephalos (as Jane said, IIRC it’s a head-feet in Greek).
Apparently the Romans pronounced their Cs like Ks much more often than we do, as has become apparent from things like finding an inscription of the name Cicero in Greek letters rendered as Kikero. I’ll never get used to that one, especially considering a ‘kikker’ is a frog in Dutch – calling a respected ancient statesman ‘froggy’ is not something that sits right with me. At that point I decided I was using those words in my Dutch speech, and most people won’t be aware of (the pronounciation details of) the original source, so they might as well conform to the Dutch rules, instead of their language of origin. So I get your point, Paul, but respectfully decline to conform to it (except when I feel like it).
Jane, Cephalopod is like GIF/JIF or Giga-/Jiga-, opinions vary. The creator of GIF pronounces it jif, and has declared that to be standard. Early, Giga- was pronounced like jig, as in Back to the Future’s 1.21 Gigawatts; but usage changed and it’s now (nearly) uniformly pronounced as in gigantic, which is fair enough since that’s the root IIRC.
Cephalopod is a little different, but nicely many online dictionaries will pronounce the word for you so you don’t have to look up their particular and usually arcane denotation of pronunciation. If you go to Merriam-Webster, you’ll hear Sef. If you go to Oxford, you’ll hear Kef, but if you go to Oxford’s US dictionary, you’ll hear Sef again. So, my conclusion is that it’s a US/UK difference. And -pod does mean foot, but oddly cephal- means head; so it’s a head-foot.
Both Merriam-Webster and Oxford have untold numbers of articles, quizes, and videos about words. Very entertaining sites, both.
Actually, does it make a difference whether one pronounces it with a hard “C” or a soft “C”? Many words have been “appropriated, not only by the English language, but some English words have been used by other people, as well. Take “baseball “, for example. The Japanese pronunciation is “bay-sa-BA-ru”. If you know what the other person is saying, and the rules of the language are such that a “C” followed by an “e” is pronounced as a soft “c” with an “s” sound, is the meaning of the sentence changed by that pronunciation? Not in my opinion, and yes, I took both Latin (classical and vulgate) and Greek (koine & Attic).
I’ve thought about how difficult it would be for a purely marine animal to gain technology. Their spaceships would be very heavy. On the other hand, they could take a lot more gees than an air-breather.
The handedness of life/universe remains an unknown problem. It is easily observable, but not explicable ab initio. If you perform similar reactions in a chemistry beaker you get a racemic product (equal distribution of handedness) unless you take special pains to template the reaction in one direction. Use of a chiral catalyst can result in 99% left handed results, and the assumption is that some of life’s building blocks arose in/around a clay matrix which is known to have these effects.
Likewise there’s no particular reason why life is limited to the 20 amino acids we see, it is possible to construct others, and through GM create organisms with new properties. But these are never seen in the wild.
RNA likely can before DNA, and hence some kind of RNA life (close to viruses?) might be possible.
One of the interesting theories is life arising inside the honeycomb of undersea vent structure: confined area, high temperatures, abundant minerals. If this is so. absent early Earth’s methane, it may still be going on.
Question: Suppose one had a batch of “Left-Spiral DNA,” and I suppose, “Left-Spiral RNA” to go with it. Would the usual amino acids that go with our right-spiral DNA and RNA have the same attraction to the Left-Spirals, or would some others instead? Or would we get a few from the usual and a few that were more attracted to the left-spirals? I ask, because I don’t know the chemistry of it, and because I would guess that some would and some would not. So you’d end up with a different sort of life starting.
Another Question: So if all we see in the wild on Earth is Right-Spiral DNA / RNA, then should we assume our righty kind out-competed the leftie kind, or that the leftie kind for some reason did not start, or was wiped out? If Left-Spiral is equally likely, then can we conclude anything, in the lack of evidence for Left-Spiral in life on Earth?
Hmm, very interesting that completely new life formation could be going on still. That makes sense of course. But there would, I’d guess, be different conditions now than on primeval Earth. Hmm, or at those hotspots, no, I guess it’s essentially still like early Earth.
Wow, how amazing it is that we still have this going on, that we could get some brand new branch of life either starting from scratch, or evolving from existing lifeforms.
What else would be likely to develop from mammals or from birds?
What got bypassed on the way to the present day that could have had just as much chance at success, from say, dinosaurs, birds, early mammals?
Very interesting stuff.
Answer: Suppose one had a batch of “Left-Spiral DNA,” and I suppose, “Left-Spiral RNA” to go with it. Would the usual amino acids that go with our right-spiral DNA and RNA have the same attraction to the Left-Spirals, or would some others instead? Or would we get a few from the usual and a few that were more attracted to the left-spirals? I ask, because I don’t know the chemistry of it, and because I would guess that some would and some would not. So you’d end up with a different sort of life starting.
That’s quite a leap of faith–there is no “so” about it! There is no evidence that “Left-Spiral is equally likely”.
While it is true “the absence of evidence is not the evidence of absence”, the observations we have show that the processes involving reproduction down to the molecular level are just unpredictable enough to constitute “exploring variations to determine fitness of alternatives”, but not so unpredictable as to preclude reproduction. Thus we have ancient animals that evolved hemoglobin from hemocyanin ancestors, got a richer “energy budget”, and survived in more expansive environments.
It is certainly arguable that where there are better biochemistries, life will find and use them, and that can be put in the past tense.
What we do know of chemistry does preclude both all sorts of variation to biochemistry, and any sort of biochemistry in many sorts of environments. “What if” must remain fantasy.
BS Chem, CSULB ’67, here. (Not making the “Appeal to Authority” of course, but a evidence of a bit deeper than average study and understanding of what’s involved. My opinions are my own, but do have a highly arguable basis in physics and chemistry.)
Just because one can imagine something doesn’t make it possible.
Symmetry is violated at the Quantum Mechanical level! How far that translates into the “macro” world isn’t known yet.
Yes, chemlab experiments with chiral molecules may produce racemic mixtures–as may biologic reactions! (c.f. Louis Pasteur separation of twined tartaric acid crystals, https://en.wikipedia.org/wiki/Louis_Pasteur#Molecular_asymmetry, and yes, it is second only to the discovery of the Periodic Table!) But it remains to be proven that dextro-rotatory life will ever evolve.
The Laws of Thermodynamics always dictate what happens at the “macro” level. “Thermo” will always condemn animals using hemocyanin, https://en.wikipedia.org/wiki/Hemocyanin, to “second class citizenship”. Hemoglobin is and will always everywhere be found to be the more efficient oxygen transport, providing more energy, more efficient, hence capable, animals.
Will it always be oxygen, or carbon for that matter? It will never be fluorine or chlorine, for much the same reasons it will never be silicon. (Sorry, Horta, back to the stuff of dreams.) It’s all about the binding strength of the valence electrons, and their availability, 1, 2, or 4, for reactions.
Just because one can imagine something doesn’t make it possible.
Lemme give you the 6-bond carbon story:
https://www.sciencenews.org/article/carbon-can-exceed-four-bond-limit
Certainly, but we’re talking about life, which means stable molecules. This puppy is, as it says, an ion (they stole not one but two electrons) only stable in strong acids. And it is a very strong oxidizer, i.e. it will steal its two electrons back from anything possible. Even as it is, it’s bonds are weaker, not something you can build complex molecules on.
So, do we want to talk about life and biochemistry, or about how wierd Chemistry can be?
OK, I still don’t understand, and that doesn’t answer the question I have as someone with only an A in high school chemistry back in 1983 or 1984, and no college chemistry.
I’m unclear as to which direction, right or left, Earth life’s DNA and RNA spiral in; their chiral direction (chiral is handednes or winding direction). What I got from above was we (Earth life) are right-handed chiral rotation. Our DNA and RNA spirals to the right.
If, as stated by another poster above, left-handed and right-handed spiraling are equally likely, was the condition the premise I was asking about.
So if left-handed spirals are equally likely, then what would chemistry predict would happen as to the development of life with that chiral direction? I asked if (1) the same amino acids as are found in existing Earth life would be as likely to bond chemically and allow the processes of life, or do they not, because of their structure, so that other similar but more, er, left-philic (sinstrophilic? I have no idea of the technical term) more left-attracted, left-fitting amino acids would take the place in left-chiral analogues.
That is asking a scientific question, asking for a prediction based on known chemistry. It is NOT merely coming up with something as sheer fantasy. I was asking for clarification, for what might happen. If left-spiral chains are equally likely, *even if they are not observed in nature but are within the realm of possibility, because they have been shown as likely in experiments*, then one can suppose that biochemists could predict what would be attracted, what other amino acids, as again cited from previous posters and not myself, would be likely to match up, thereby to predict if left-spiral life would be more similar but for the chiral direction, or less similar to Earth-based life as observed in nature here on Earth.
Why is asking for a scientifically-based prediction from known experimental results in the lab, equated as impossible and unpredictable, because it is not seen in nature on Earth in the wild? Put another way, if it is within the realm of possibility from lab-run science experiments, then should we not be able to say what might proceed from that, what amino acids, as in the example, might be likely to combine? I am sure that the ones in existing Earth-based life have physical, chemical structures that either do or do not allow processes to occur with our own spiral directions. I am also sure that either they will also fit the other chiral direction, or they won’t. And I’m sure that other similar amino acids might instead fit better in the physical, chemical structures. So it must e that one can have some scientifically probable prediction, a condition, a hypothesis, a test run (many) to determine what happens, and that one should be able to work out through chemistry knowledge what is likely to occur.
That’s what I was asking about.
I was not trying to ask if you could just stick molecules ABC and XYZ together and presto, come up with a dragon, or a tree octopus. Or a common lab mouse. I wasn’t trying to say you could invent elements that don’t exist. Or other fantasy. I was asking a genuine question whichh, dang it, I should think you’d e able to say something about more useful than, “it’s impossible, you’re spouting sheer fantasy, because it hasn’t been found on Earth, end of story.” Science + Fiction = Science Fiction. One can speculate about what else could exist elsewhere, and do something towards predicting it, as a thought exercise, rather than to dismiss it out of hand, because it seems too fantastical. If we can see through experimentation that a thing is even somewhat likely, and for sure, if it is about as likely as what’s in nature, then why should we not try to work out what would be the logical progression down the line, just for sheer scientific exploration, for the fun of it?
I don’t understand why, when I or anyone posits speculative things like that, that you answer, it’s sheer fantasy, don’t bother even looking at it.
If it s possible in known chemistry, then one should be able to predict it, and it is reasonable to explore the question for its scientific and educational value. Come on, man, isn’t that part f the fun of doing science? Of doing chemistry, your own field?
And OK, if it is not possible, then explain why, to a layman, in terms the general public can understand, but don’t simply dismiss it as poppycock, please. Also please remember, science fiction is speculative fiction built on exploring ideas, involving scientific prediction, even if they are only theories or are not as likely, but are plausible, in order to think about what could happen, what cold be out there. That’s pare of the sense of wonder, the sense of exploration of nature, of science, of what could be. That’s a plausible what-if. So wy nt address that? Say why it can’t be, in layman’s terms, if it is not possible in science. But if it is demonstrably possible in lab experiments, then why not explore the idea? For fun. For learning.
Silicon-based life has been one of those what-if theories for a long time. Supposedly, the chemical structure of silicon is similar enough to carbon that some people have said, why wouldn’t silicon-based life be possible. — You have said before and are saying again that it is not possible. OK, why? If it has been proven to be so unlikely, why is that? too few things will work? Too much would have to e different? As I understand it, it’s still considered a remote possibility, even today, by reputable science. If I’m wrong, then OK. But why? And why simply dismiss a theory that has held at least some scientific plusiilty for years, without saying why, other than it’s fantasy, and then to equate it with inventing things out of whole cloth?
I’m sorry, but if you intend to put things that way, then as someone who did have some technical education in science as well as liberal arts generalist approach, then I would ask for a better defense, a fuller approach, than saying so many people are spouting fantasy, and saying you think their ideas are completely impossible.
As a scientist, you should be able to explain why, in simplified terms, without branding others as inventing things out of thin air. You should be able to consider what is plausible in science and explore it for its own sake. You should be able to explain what is and is not possible, or at least likely, and to predict somewhat on a basic question, what might proceed from a reasonable question.
Please do not simply say it’s sheer fantasy and dismiss it out of hand, without first giving some readily understandable explanation.
Why not mess around, thinking of possibilities and exploring them? That is also basic science. It’s how we got the most basic scientific questions answered, and why we still investigate things, to see what happens, to learn, to test ideas and see what does and does not work, and keep on until we know a little more.
I think that would be a better response than saying other people are just throwing things together and it’s all impossible unless you can see it here on Earth. If one can see precursors in lab experiments with even a modest rate, then that’s a thing that can be investigated with good science. Even 5% or 10% would be worth looking at, because it’s possible. Anything above 25%, I should think would be easily worth looking into. If it’s 40% to 60%, or even 33%, then hey, that’s entirely likely to occur somewhere in the universe. — And if it does or if it doesn’t, we should be able to say something scientifically about *why* it is or is not possible, and what is likely to happen when it *does* occur in nature, somewhere in the universe. Basic science, man.
Why would you simply say it’s completely impossible? More, why say it’s coming up with something with no basis in scientific fact? Why, if what’s being asked is from someone seeking to understand what someone else said has been shown through lab experimental results? Why not explore this? It seems like that would be a fascinating question from a chemistry or biology perspective. If it’s at all possible, then why did it nt survive, right along with what we have on Earth? If it’s possible, then it may well exist elsewhere, not yet observed by humans. If we can see precursors and plausible, explorable questions in lab experiments, then why not seek to find out the answers and predict the results, and check to see if they can happen? Basic science, not dogmatic dismissal. That’s why I’m asking for, thanks.
“If, as stated by another poster above, left-handed and right-handed spiraling are equally likely…”
You postulated your conclusion! Don’t you see that?
You misunderstood, that is not what was said.
This is what was said:
You can’t even get started on your way to DNA with simple chemical reactions like that which produce racemic mixtures.
The fact that some chemical reactions produce racemic mixtures of enantiomers, is not to say that left-handed DNA exists or can be produced. We don’t know that it can or can’t. We can make no presumptions that it can, because we have never seen it, and that fact must give us pause. Mother Nature may know something we don’t.
(After all, what better way would life have had to protect itself from being eaten than being totally indigestible?)
“If, as stated by another poster above, left-handed and right-handed spiraling are equally likely…”
You postulated your conclusion! Don’t you see that?
You misunderstood, that is not what was said.
This is what was said:
You can’t even get started on your way to DNA with simple chemical reactions like that which produce racemic mixtures.
The fact that some chemical reactions produce racemic mixtures of enantiomers, is not to say that left-handed DNA exists or can be produced. We don’t know that it can or can’t. We can make no presumptions that it can, because we have never seen it, and that fact must give us pause. Mother Nature may know something we don’t.
(After all, what better way would life have had to protect itself from being eaten than being totally indigestible?)
1) I did not say it’s impossible that left-handed DNA could exist, but that I think it’s highly unlikely.
2) It is impossible for me to condense four years of a degree in Chemistry to explain why in this blog.
Sorry for the overreaction and lengthy post, but it did strike a nerve, and my points, I was trying to get across, are valid, I think.
I wasn’t expecting an in-depth explanation requiring an undergrad chem-e degree. I was looking for a layman’s explanation, as I’d said.
I had thought it would be possible to speculate, from a chem major background, on what might be plausible, even remotely likely. Too bad.
OK, you think it’s too unlikely to exist. Yet Earth life is not likely to be the only biochemistry answer to exist in all the planets inner galaxy.
Sorry that it seems too unlikely to consider other possibilities allowable in known biochemical laws..
I did say my opinion was arguable, but it’s neither original nor idiosyncratic. I’ve read many scientists make that same point.
I did as you ask, “I had thought it would be possible to speculate, from a chem major background, on what might be plausible, even remotely likely.” You just didn’t like my answer!
“Yet Earth life is not likely to be the only biochemistry answer to exist in all the planets inner galaxy.” Says who? Is that an article of faith? Several times you have postulated your conclusion. All I can say, again without trying to teach you a complete undergrad course in Physics and Chemistry, is the chemical/physical properties of the elements and they molecules they can make, are limiting. Anything is not possible, not in this universe.
@Paul, I *really* was not trying to say “anything” is possible. I was instead speculating from what I’ve seen discussed and asked what *is* possible, or at least remotely so, and asking for an exposition from there. I’m sorry we’re at cross purposes.
I really do recognize there are going to be some things most likely, some somewhat, others less, and others, so unlikely as to be not observed.
I do recognize there are good, solid physical and chemistry-based and biological reasons for this.
I’m sorry, I had thought possibly you’d be able to say something about what *is* possible or likely, within known science, of what might also exist out there somewhere.
That really is not trying to say “anything is possible” or to invent stuff out of thin air. I was just speculating. OK, so you say it’s not likely and not possible, beyond what’s observed, though you admit other things could be possible. I was hoping for something along the lines of what is possible and how that might work on some other world, closely similar to Earth or otherwise.
But we’re clearly not going to see each other’s points on this. Sorry for that. I’m dropping it, but had wished for something more informative and fun in science-based exploration of possibilities. Sorry to have bothered you.
I’m not bothered, it can be one of the characteristics of Aspies.
Read this from the National Academy of Sciences, “The universal nature of biochemistry”: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC33372/
Even this:
https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry
Scientists have been considering this, and have generally reached the conclusion that Tully and Pyanfar, Bren and Ilisidi, could share a meal, but Horta will never be found.
Thanks for the link to this article, Paul. It is an excellent and wide-ranging overview.. And thanks for the Symmetry article blow too, which stretched my comprehension capacity a fair amount but adds depth to some of the astrophysics I was reading a few years ago and need to get back to.
Both articles increase my desire to take a decent course in Organic Chem and in (Astro)physics.
People often misunderstand Science & scientists. While it’s so very conventional to get a PhD in a scientific field, deriving from the historic “Natural Philosophy”, there is a rare DSc. When one really gets into pure Science, one doesn’t go too far before encountering epistemology, i.e. how do you know what you think you know? And how we make sense of observations and direct our investigations to form hypotheses may be very mysterious, a talent.
I think it’s not a coincidence I’m an Aspie. Hans Asperger noted in his initial subjects an ability do coordinate facts into coherent, interlocking, explainable whole structures. Looking back on my life, I think I was a “natural born” scientist, taking hold since I was about 12.
Thank you. That’s precisely what I was looking for. I’m halfway through the Wiki article and will read the other article later.
Not quite “precisely”. They don’t answer your question about symmetry. Turns out that’s one of the really BIG unknowns, on par with the matter/antimatter question.
Read this: The role of symmetry in fundamental physics, http://www.pnas.org/content/93/25/14256.full
My PoV has always been based on Science. We start with observations of nature, make hypotheses, test them with predictions, never withdraw the Rule of Falsifiability. You will find in the article above the sentence, “I believe not.” There come points in these unknowns where even scientists, knowing the knowable, line the facts up on the balance as seems to make sense idiosyncratically, and come up with hunches. Thus they’re arguable. For me, the most plausible answer is: it was not chance that the Great Symmetries aren’t, for reasons yet unknown, and we’re made of matter, eat left-handed sugars and have right-handed DNA. When everything is this way rather than that, I think there must be a scientific reason it couldn’t have been. You may disagree, but I’ve pretty good legs to stand upon. 😉
But it admits of the possibility within known scientific principles and discusses things, rather than simply putting its foot down and saying no way. It doesn’t answer all my questions, but it’s close. It gives me a better understanding of might and might not be possible with silicon-based life, for instance.
The Wiki article questions why we don’t see chirality in the other direction much, but gives examples where it exists. It then neither draws conclusions for or against, but leaves the question as a possibility and an unknown. To me, that’s a responsible stance. The article is presented so that someone with an interest but not a specialization can see what they mean. It elucidates, it doesn’t leave it in the dark.
And look how long they are! I think I/we have already imposed quite a lot on CJ’s own blog. No way would I have explained all that, perhaps did too much already.
You asked of there could be left-handed twisting DNA, life elsewhere built mirrorwise. That article did not answer the question. It cannot be answered with known observations. One would have to take that as a starting point, and use scientific judgement to answer your hypothetical. Understanding chirality was (a small) part of the requirements for my degree! One tried to distill everything down to just simple answers, with minimal explanation of what is answered. One did the best one can do to answer the question.
Just my two cents: In the lab compounds can be created with reverse chirality. I remember reading about a form of sugar that was developed from reverse chirality that tasted just as sweet as regular table sugar but could not be metabolized by the body because of its reverse twist.
All life on earth shares the same chirality because it developed from the same common ancestor. Having two forms of chirality would make common biological functions such as meiosis and mitosis impossible because the cellular mechanisms to zip and unzip DNA, enabling duplication and cell repair would be stopped because the cellular machinery had the wrong shape to follow the twist of the DNA strands. It is probable that virii with the wrong chirality would not even be able to broach cell walls. There is nothing to stop beings from different planets with reverse chirality from meeting, but the metabolism of food from each other’s planets would probably be impossible and downright painful. Think diarrhea with no useful nutrients absorbable other than water itself.
Some common ancestor with a particular twist is the commonly given “reason”, but it isn’t satisfying. If, as the presumption goes, either handedness is possible and equally likely, it strains credibility that nowhere else did any “mirror-image” cell form and reproduce. Where are they?
And look how long they are! I think I/we have already imposed quite a lot on CJ’s own blog. No way would I have explained all that, perhaps did too much already.
You asked of there could be left-handed twisting DNA, life elsewhere built mirrorwise. That article did not answer the question. It cannot be answered with known observations. One would have to take that as a starting point, and use scientific judgement to answer your hypothetical. Understanding chirality was (a small) part of the requirements for my degree! I’ve tried to distill everything down to just simple answers, with minimal explanation of what is answered. Don’t criticise me for answering your question!