Give it a couple of million years
And there'll be a human output in every corner of the galaxy.
Earth appears to be unique and inhabited by living creatures, but the building blocks required for life to bloom are actually quite common, according to new research. "Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth", said Siyi Xu, an an assistant …
"And there'll be a human output in every corner of the galaxy." No, unless 'human' is a generic term for tool and language using sentient creatures rather than homo sapiens. Perhaps we shouldn't be speciest.
Interstellar space is like a quarantine system. Unless there is physics we don't know about. A generation ship is theoretically possible. No evidence that cryogenics does anything other than kill mammals. Some sort of hibernation with a short awake period every few months might be plausible.
SF needs starships. It doesn't mean they have to exist in the real universe, though it would be interesting if they did.
This article seems pretty dated, as more recent research suggests that most of the variance between different subgroups of humans is due to mixing with other human species like Neanderthals, Denisovans. The timeframes mentioned in the article are nowhere near enough to "evolve" in any capacity. The evolution happened over much larger timeframes and across the entire homo family tree.
Epigenetics is not evolution nor is it mutation. It is the expression of "suppressed" genes due to changed environmental factors. The genes are already there by normal inheritance but another set or even the same set are just expressed differently due to need; think lung size when changing from a low altitude to a high altitude environment and vice versa.
Native High Andes dwellers have larger lungs than the norm, move them to a coastal environment and in three generations their lungs are the same as the norm. Move them back up and three generations later they have large lungs again.
Basically it's 'stored' responses to conditions experienced by the ancestors and allows fast adaptation to changing conditions.
"Epigenetics isn't evolution"
Epigenics and evolution are closely intertwined. Evolution and mutation happen all the time - in fact the pool of mutations and evolutionary tweaks maximises during unstressed conditions (such as our species is experiencing now). This is why our species is evolving faster now than at any point in its history - but that's happening in all directions at once with no clear advantage to any particular change.
It's only when stressful conditions or new niches come along that some of those will prove advantageous to the individuals who have them BUT they're only useful going forward if those genes are passed along AND the descendants stay exposed to that condition in order to further enhance the selection.
Environmental stress points act as a filter, removing the unhelpful evolutionary changes (in the case of widespread environmental change) or splitting development into lines suited to a particular environment vs a more general one."Survival of the fittest" was never the best way of expressing that because in the vast majority of changes it's the latter, not the former - but then those specialisations frequently run into dead ends and extinction when the "particular environment" disappears (so in the long term, the generalist survives whilst the specialist doesn't)
"The timeframes mentioned in the article are nowhere near enough to "evolve" in any capacity."
There are extremely noticeable changes in "recent" human history which coincide with the agricultural revolution: Thinner skulls, smaller jaws, flatter teeth.
All three of these changes have happened within the last 15k years and spread rapidly amongst virtually the entire human population.
"Our genetic makeup is pretty much the same"
Exactly my point. Don't forget, people, that the person I was replying to said that humans in 10,000 wouldn't look anything like us now. While being taller or shorter, or having a bigger or smaller brain, etc, may well be significant changes, they are a long way short of that. I said we haven't changed that much - and we haven't; we would easily recognise a human of 10,000 years ago as, well, a human.
"Our genetic makeup is pretty much the same"
For that matter, our genetic makeup is almost identical to Bonobos.
And then there's the whole Cabbage/Cauliflower/Brussel sprouts/Broccoli/Kale/Brassica thing - all the same species but wildly different appearances.
We are very different from 10000 years ago. We know a female from a village in Australia could run faster than usain bolt while "Jogging" on a beach. (from the stride distance of preserved foot prints)
Since then we have gone backwards in terms of strength, fitness and our ability to process food stuffs, illnesses even certain weather because we have clothes and shoes and medicine to help. Which in turn has let us survive as a weaker form, live longer etc.
We were also much much shorter, a few hundred years ago, never mind 10000. Just look at Japan over the last 50 years to see how changes in diet and lifestyle can impact height. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5811819/
Today we have AI, robots and a massive obesity problem because our diets and lifestyle are very different. You think in 10000 years it won't have changed us again.
Assuming we are alive in 100000 years as a species.
Our ability to process foods is certainly not going backwards, you find just about everything you can wish for in supermarkets. Medicine is getting better all the time and cancer treatments are improving, although not by leaps and bounds.
Finally, we do not have AI. We have continually improving statistical analysis machines that work on very specific data sets, but that is not Artificial Intelligence.
We certainly do have an obesity problem, but that is exactly because we know how to process the shit out of food. And we're all lazy as fuck, at least in the traditionally-named "developed" countries. Maybe if we didn't have 150 different types of chips, things would be a bit more under control in the belt area.
Quote: "Our ability to process foods is certainly not going backwards, you find just about everything you can wish for in supermarkets. "
Woosh! They are talking about *our* ability to process food, i.e. in eating, how our guts handle food, not about how we process food in a factory somewhere!
" cancer treatments are improving, although not by leaps and bounds."
Bear in mind that the primary reason more people are GETTING cancer isn't down to environmental factors for the most part(*). It's because more people are living long enough to GET cancer in the first place (or have small ones progress to the point where they're the cause of death rather than something that was present at death but not the cause.
(In the same vein, people throw out the stat that the rise of the rate of cancers in domestic dogs and cats in the 1970s directly tracks the increase in the rate of use of canned/bagged petfood - but neglect to mention that it also directly tracks the increasing lifespan of those pets in the same period.)
(*) There are definitely clusters attributable to environmental factors but overall it's age-related - and high levels of ionising radiation exposure doesn't usually CAUSE cancers, but by suppressing/damaging the immune system it frequently allows existing ones to grow faster than they usually would because the body's not killing off the mutated cells.
Right. My first cat (owner), a female Seal-Point Siamese, lived until she was 23. My second, a Burmese, lived until she was 27. She was hanging on my screen door yowling her head off, didn't know she was already 11 until we had the vet look at her. My Mom's, a 28# Maine Coon-Cat, lived until he was 20 even despite the fact that he had diabetes.
We are properly trained cat slaves around here.
[Hell, I just had a 18# male mixed breed cat try to come home with me. Strolled right on out and surrendered to me (rolled up on his back exposing his neck and stomach) on the spot. A 4.5 month old kitten just strolled on in one day, three months ago, and took up residence. Never a problem having a cat, or three, around. ]
10,000 years of corporations getting rich by selling us crap that makes them money and us sick? Icon? I'm checking for some cash to go and get breakfast ... a bowl of granola with a extra dash of Roundup please, and some milk with bovine somatotropin too while I read the FT and see how my shares are doing - going up again, wonderful!
Avatar of They - it seems you don't understand natural selection at all. You are describing the influence of environmental factors on a static genome. H sapiens sapiens has been around for a couple of hundred thousand years with very little variation. Things like height are very much diet and exercise related; thus hunter gatherers tend to be taller than subsistence farmers. But the average height and weight of Britons has changed in the last 70 years due to food availability, showing this is short term environment change.
In fact we are little different from Neanderthals.
As another example, dogs started to be domesticated roughly 17000 years ago. Huskies split off from dogs about 8000 years ago. Because of the flexibility of the dog genome, we have produced numerous breeds - but cross breeding rapidly causes reversion to Mk. 1 dog. And most people do not even realise that huskies are a different race of dogs. This despite intensive breeding.
Just need 1G acceleration.
At that everything becomes very travelable indeed with time dilation making the journey appear vastly shorter from the perspective of the traveller. With 1G you can get to other galaxies in a single lifetime of the traveller, even if millions of years pass back on earth. You never actually reach the speed of light, despite constantly accelerating at 1g for half the journey and decelerating for the other half. The energy requirements are staggering tho, even if you can find a way of pushing off without lobbing stuff out the back.
Not possible for very long. A variation of the rocket equation applies to carrying the fuel (even antimatter), the longer the thrust, the more fuel and thus the more fuel needed for same thrust due to higher mass.
Forget solar power (light or wind) except to accelerate to edge the Kuiper belt. The Oort Cloud is about a thousand times further than the Kuiper belt. Any likely nearby stars are 10x to 100x further. Space is really really big.
Secondly, you need more thrust to maintain 1G as you get faster.
It's probably not possible to maintain 1G even 1/2 way to the nearest star. Basic physics & mathematics says no.
Many ways around this have been proposed, Light sails + lasers/masers work, for longer distances one option is to relay them making interstellar highways, the only obstacle to that is local power generation.
Some promising hints of massless thrusters are appearing with the EM drive and alike. Then there is just a simple Photon drive which is already in existence (just shoot a laser out the back works, but you need a lot of light to make 1g on anything).
Relying on chucking stuff out the back is never going to get man much beyond mars
If you could accelerate at 1g for one year, you would reach the speed of light. Decelerate at 1g for a year, and you are done. Assuming you don't hit anything - since you are traveling at the speed of light you have no way to maneuver around anything - by the time you could sense something you are already there.
"The energy requirements are staggering tho, even if you can find a way of pushing off without lobbing stuff out the back."
It's somewhat easier if you use a torch or pulse system (safe in space as long as you're not close to the business end, not so wonderful in biospheres)
Ideally you'd need a Bussard ramjet for fuelling but they very likely are the realms of science fiction.
What Crisp said was that there will be a human output in every corner of the galaxy. In other words, someone is going to poop in the corners of the galaxy. Going to take a good chunk of those couple of million years to figure out where the corners are, though...
The universe is probably teeming with life but in forms that we do not recognize or understand or are capable of understanding from a chemical/physical point of view.
I know that I am a pressimist and as much as I can understand the desire to search elsewhere I always feel that there is far more need to take care and improve whats already here..
If we were to discover an alternative lifeform I am sure that they would be disgusted at what we are doing with the planet that we already have..
Before venturing elsewhere we need to take care of GAIA before se decide to take care of us... Then we should begin our ventures elsewhere.
Venturing elsewhere is how you go about cleaning up where you are now. It's a lot easier to clean a house when it's not being lived in, think about it.
Moving off world and expanding usable space, reduces our demands on the earth's natural resources, giving its ecosystems time and space to recover.
Let's face it, it's not going to get any better while we're squabbling over the tiny scraps of what's left after we've destroyed most of it. Expanding outward is our best, and frankly, only, hope.
"Venturing elsewhere is how you go about cleaning up where you are now. It's a lot easier to clean a house when it's not being lived in, think about it.
Moving off world and expanding usable space, reduces our demands on the earth's natural resources, giving its ecosystems time and space to recover."
Oh, so you mean that we can take our actual bad habits and continue to deploy them elsewhere ? Using even more resources and poluting something else.
We have to tidy up our own backyard first before we can start to imagine moving elsewhere.. We have successfully put a lot of things in the atmosphere and some of it is already in the "junk" status.
"We have successfully put a lot of things in the atmosphere and some of it is already in the "junk" status."
Yup and that's all dangerous because
1: It's close in
2: it's moving fast
3: It's all in the same place (more or less) due to orbital mechanics.
Once you move out of the earth's gravity well and stop focussing on a particular blue-green rock there's a lot more..... space..... to play with.
>Moving off world
Have you any idea of the energy requirements of moving even a fraction of the world's population off world? (Not to mention to budget for going somewhere else and surviving there.)
In any case, if we can't learn to live on this platform, how the hell can we learn to live on another?
"The universe is probably teeming with life but in forms that we do not recognize or understand or are capable of understanding from a chemical/physical point of view."
On the other hand every time we've assumed our conditions are "special", we've been proven wrong.
Water and carbon are some of the most common items out there in the universe. Most other possible chemistries are difficult without extreme (from our point of view) temperatures and would be heavily poisoned by the presence of either of the above. That's not to say they're impossible, but carbon-based life is the most likely form. It could be anaerobic or aerobic but it's a fairly safe bet to assume that within a few billion years of anaerobic life evolving on any planet with access to sunlight some species will develop a way of harnessing the light energy and splitting water in the process, generating oxygen in the process (which will kill off virtually everything else, as happened on earth)
Seeing an oxygen signature in any planetary atmosphere is a telltale indication of life "as we know it" - the "plants" may not be green (that's an artifact of the light frequencies available to the first chloroplasts trying to get light after the blue-green and red algae had hoovered up most of it), but it would be carbon-based, water-splitting and light-eating.
Carbon-based anaerobic life would virtually always inevitably give way to aerobic life due to the evolution of oxygen-generators. The harvesting of available "free" energy (much easier to deal with than thermal energy) makes this almost certain over evolutionay time periods. Even if the results are random when you throw the dice, eventually you will throw 5 sixes (Yahtzee!) 4 times in a row. It's only a matter of "when" and nature is endlessly patient.
> "Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth"
If being "earthlike" was enough, this planet would continually be spawning life, as it originally formed. Those "respawns" would then start their own path of evolution. So as well as having us, the result of billions of years of evolution from the first time that life appeared, there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on.
But we don't. We only have a single thread of evolution that seems to go back to the start.
So it would seem that being "earthlike" is not a good idea for a planet if it wants to start producing life. It is only a hospitable environment for once life has got past the initial stages. After that, being earthlike is not a set of conditions that is suitable for starting evolution.
The conclusion would be that a planet only has one shot at starting to give rise to life-forms. Maybe once they get to the stage of converting methane, CO2 and ammonia into an environment rich in water and oxygen, they have past the point of spontaneously allowing life to form. If whatever life had developed, then died out, it would explain why we don't see other planets' TV.
The trick wouldn't be starting life, but in having the remarkable set of coincidences, luck, and starting conditions to allow life to avoid all the extinction possibilities in the billions of years after it forms, to eventually give rise to intelligence. Or us!
there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on.
As humans, we have told ourselves the comfortable story of a single thread of evolution, but actually, if they are all based on the same chemicals, then we have no way of telling whether any of what we know of the fossil record and current species are from a first or subsequent attempt at life.
There's no reason why new life isn't making a new start every day but unless it is sufficiently isolated to evolve a little and develop defence mechanisms, it won't survive for long.To develop defence mechanisms will also require something to predate or compete with it, that takes time so one of our pre-existing and hungry organisms will likely find it before is gets far enough.
Expecting alternative routes for life forming at a later stage in evolution is for the reasons mentioned above, unlikely.
Everything alive on Earth today shares the same basic molecular machinery, implying a common ancestor. But yes, any of the previous mass extinctions could have been a full stop for some completely different lineage. Interesting thought. Dirty keyboard icon in case a new, more effective, ribosome has just evolved on it thus marking humanity's doom.
"we have no way of telling whether any of what we know of the fossil record and current species are from a first or subsequent attempt at life."
There's quite a lot about life that could be different but isn't. The set of amino acids in proteins is one and the coding between nucleic acids and amino acids is another. Given 4 types of nucleotide one base pair is worth 2 bits of information so the 3 base pair codon represents 6 bits which is one one hand the minimum but on the other contains many redundancies. A smaller set of amino acids could result in a much more efficient 2 base pair codon and we might expect to see that if there were parallel life chains. Our genetic code is highly conserved, even between such different organisms as animals and plants; we don't see other, equally well conserved, genetic codes amongst the rest of nature. It's possible, of course, that any alternative starts could have been out-competed or simply eaten but, knowing the way life forms survive by interdependence, it seems likely that, had they existed, at least some of them would have been readily recognisable parts of the Earth's ecosystem.
The code seems very redundant but the code table as it is gives certain very specific structural features which make (at least) recombination easier for certain specific sequences. In modern organisms this minor advantage is unimportant but in simpler beasts it may have been decisive in bootstrapping some of the complex but vital machinery such as ribosomes and recombinases. https://doi.org/10.1017/S0033583517000130
"So as well as having us, the result of billions of years of evolution from the first time that life appeared, there would also be forms of plants, animals and all the rest that are the product of evolution from the second time that life started on Earth. And from the third, fourth, the seventy-seventh, the 2,916'th and so on."
Modern life has enzymes that make DNA replication fast. Early life did not. Nip back in your TARDIS and bring some early life here and it will get eaten before it can reproduce. Perhaps life did start multiple times in Earth's distant past but it cannot do so again while every habitable environment on the planet is infested with organisms selected by millions of years of evolution to be efficient at exploiting their environment.
Perhaps life did start multiple times in Earth's distant past but it cannot do so again while every habitable environment on the planet is infested with organisms selected by millions of years of evolution to be efficient at exploiting their environment.
This. All of this. And entirely this.
Even the humble garden slug is an ultimate bad-ass in its own niche. It has fought and defeated every challenger for its particular (narrow) environment. Having evolution start all over again - a fresh roll of the dice to spawn entirely fresh organisms - is not impossible, in my view. However, it'd be like putting a newborn infant up against special forces troops. In a straight fight it's just going to lose.
The only option is for this new evolution to find an unexploited niche. Perhaps this is why extremophiles are just so bizarre - maybe they have arisen as totally fresh instances of life, separate from whatever chains have spawned us, and they've just been the first into that environment. Maybe not.
Who can say? Without a way to go back and see it's impossible, and the car's in the workshop today - brakes are binding, so getting 88mph is a bit of a slog. Besides, the flux capacitor is being tricksy just now.
New proto-living chemical systems capable of starting off a de-novo evolutionary tree may well be continually starting up in the tide pools and subterranean vents of Earth's oceans, and being enthusiastically eaten by the the teeming swarm of microbes which already live there.
This is not quite correct. It is reasonable (from an evolutionary standpoint) to assume that the very first thing we could call life (like the auto-catalytic cycles proposed by Stuart Kaufman), we less efficient at replicating themselves, using available resources like food and energy, or even simply maintaining their own structure than later, more advanced cells. Once these more advanced life forms had evolved from more primitive ancestors, they most likely spread exponentially, and would out-compete any new life-form trying to start from scratch. There may have been many other "starts" that were obliterated by our very, very distant ancestors, simply because they used resources more efficiently. There may also have been many starts before the successful one that lead to us, that somehow got wiped out by some disaster. Alternatively (more or less like the much later merger of proto-eukaryote cells with prokaryote, in which case the latter turned into organelles such as mitochondriae and chloroplasts within eukaryote cells), the new forms might have been assimilated within the older ones.
Let us assume that on a planet the size of earth, under the right conditions you could have a "new start" once every million years (and following Kaufman's reasoning, that is a pessimistic estimate). If we have a successful start, on average, it will have a million years of evolution before any competing "new start" arrives on the scene. That is a very long head start for the first comer.
In conclusion, there may have been multiple starts, but these multiple starts either got assimilated with the first successful one, or got out-competed.
"Alternatively (more or less like the much later merger of proto-eukaryote cells with prokaryote, in which case the latter turned into organelles such as mitochondriae and chloroplasts within eukaryote cells), the new forms might have been assimilated within the older ones."
There's a shared biochemistry in terms of genetic coding between the eukarytotic and prokaryotic components to suggest a common origin followed by a period of parallel evolution before one assimilated the other.
Life is always in competition for resources. Hence the first to evolve easts the resources required for others to form.
The BIGGEST barrier was the change from Prokaryote (Bacteria) to Eukaryote (larger more complex cells made of bits from various Prokayotes.
Consider Prokaryote life was present the moment the Earth stopped being a ball of molten rock, but it took a Billion years to go to the next stage of Eukaryote. Maybe this stage is very unlikely and so there are billions of Earth-like worlds covered in slime.
"If being "earthlike" was enough, this planet would continually be spawning life, as it originally formed. "
The planetary environment NOW is absolutely nothing like it was(*) when life first started leaving fossils here. Life _can't_ start under current conditions.
And there is evidence for exactly what you suggested (multiple independent starts).
(*) Until the Great Dying, Earth had an atmosphere mostly made of nitrogen, carbon dioxide and water vapour, with smaller quantities of methane and ammonia, virtually no land (just a few large islands), vast black iron-rich oceans and the air probably looked red from orbit. The nitrogen is more-or-less unchanged but the evolution of oxygen-emitting lifeforms in the early oceans first of all caused the iron to oxidise and rain out (banded iron formations in australia - big mining resource), then when the oceans were saturated, filled the atmosphere and oxidised the methane. Along the way they killed every form of life which found oxygen toxic (most of them), forced the survivors to find a new respiration method (aerobic) and made it impossible for life to kickstart itself here again.
Earth is the way it is, BECAUSE of life. Just about everything you see in the rocks around you (including their very existence plus that of the continents) is due to the presence of life in some form or another. And once life got a strong foothold, it ratcheted things along so it couldn't retstart.
"If being "earthlike" was enough, this planet would continually be spawning life, as it originally formed. Those "respawns" would then start their own path of evolution. "
No, we have a billion years of evolution behind us - voracious, competitive, cooperative - selective. Any new kid on the block will be devoured by our cousins the bacteria before it gets to form its first cell.
And yet we see no trees on Mars or the moon. So "earth like" requires more requirements than just "similar". And while the post you reply to is wrong, and you may be right, it is for different reasons than outcompeting life. As there is no other life on mars to outcompete, yet still no trees (or moving creatures, or growing creatures or replicating creatures).
"Earth appears to be unique and inhabited by living creatures, but the building blocks required for life to bloom are actually quite common, according to new research."
My mother appears to be unique and has breasts, says the monk that has spent his entire life in a monastery. His mother is the only woman he has ever seen. The only reason Earth appears to be unique is coz we have a sample size of precisely one potential life bearing planet. So it's no surprise that we have seen only one life bearing planet. We are coming closer to figuring out if Mars and our Moon are / where potentially life bearing, so that'll triple our sample size. We may find others in our solar system, and eventually we might find others in other solar systems. The odds are looking better each time we have a look. Once we actually know more, we may find out that planets inhabited by living creatures are common. We are still in the monastery, peeking out the window, wondering if those oddly shaped people out there have breasts like our mother.
But there is just as much chance we are the only example of life in the universe. This is not any more improbable than all planets having life, or it being somewhere in between. However, I don't currently observe life on the moon or on mars. I only observe it on earth. For places I cannot observe, I assume it is not the same as here, until I see it to be. Why? Because here and there are differences, if they were the same, there would be no description of their difference!
"But there is just as much chance we are the only example of life in the universe."
We have a sample of one planet that is definitely inhabited. Discarding religion, the probability that another planet is inhabited is non-zero; in fact we are probably looking at a Poisson distribution (p<<1-p).
As astronomy improves the rate of detection of planets around other stars is increasing - implying there are a lot of them.
For you to be correct, the probability that we are the only inhabited planet would have to be 0.5. The sum of all the probabilities (that there are 2,3...n billion other inhabited planets) would have also to be only 0.5. It is not quite infinitely improbable, but not far off. Because there is already one inhabited planet...
The probability of one location with life is not non-zero.
There is one observable universe. There is one me. There was one Elvis.
None of those statements are magical or mythical or philosophical.
They are truthful statements, that sometimes events in this universe are singular (not even counting observations we can never make, such as multiverses which we cannot communicate with/detect).
So no, "we have one, so it *must* be common" is an extreme extrapolation (XKCD for obvious reasons: https://xkcd.com/605/ ).
Most people treat it like a religion when they say "there *must* be life out there".
One thing this article doesn't mention is that earth at the origin of life was very different than today, it had very little free oxygen, and was probably abundant in cyanide and other chemicals we consider toxic.
The current abundance of oxygen, as well as the details of the carbon cycle and numerous other bio-geo equilibria are down to the excreta of various mostly-tiny organisms. This is not necessarily some benevolent gaia-system: when oxygen became abundant in the earth's atmosphere it was toxic to the vast majority of the extant biota, and broke the greenhouse effect, causing a planet-covering super glaciation which lasted for millennia. Planetary chemistry could have followed many different paths, and certainly started in a very different place to where it is today.
Getting life started is the original chicken and egg problem even if you take the simple monomer molecules, nucleotides, amino acids etc as a given.
Assuming you have a random string of RNA, to get to an equivalent random string of amino-acids as a protein you need a set of transfer RNA molecules, a set of enzymes to attach the t-RNA molecules to the correct amino acids and an enzyme that works its way along the RNA string, grabbing an appropriate t-RNA/amino acid complex for the next codon of RNA, linking the amino acid to the amino acid from the previous codon and chucking the t-RNA molecule back into the milieu.
That requires a number of distinctly non-random proteins to do that in addition to the distinctly non-random t-RNAs even before we start to consider how natural selection might fashion the random RNA into a functional gene producing a functional protein. And it also ignores the trick of reproducing the RNA chain and eventually moving to the DNA > m-RNA stage. That's an impressively substantial boot-strapping requirement.
We've also got to consider the energetics. We also need to assume chlorophyll or some other suitable pigment is available and that this can somehow be coupled with adenosine phosphorylation (I'm assuming adenosine is also available as one of those simple compounds). That's needed to power the protein synthesis.
It all needs to take place in a benign environment as heat and pH outside a narrowish range around 6 - 7 will denature the protein and heavy metal ions will inhibit their function as enzymes.
The set of circumstances needed to get from a random collection of simple organic molecules into a set of self-organising structures is less likely, and less likely still that they're going to survive random bombardments of extra-planetary objects, be in the habitable zone and be on a planet where the gravity isn't too strong to permit the growth of larger structures.
Biochemists (eg Kenji Ikehara https://ikehara-gadv.sono-sys.net/en/ and JT Wong https://www.ncbi.nlm.nih.gov/pubmed/1057181 ) have looked at the frozen-in evolutionary history of the genetic code together with the relative probability of (random synthesis/autocatalytic self-synthesis) for various amino acids and come up with a match - this shows that the arrival of the current ludicrously complex biological basics can be broken down into individually more probable steps, where a bunch of free-floating amino acids get pulled into a fragile self-replicating system which then develops them as as tools to make more of the same aa. Initial autocatalysis of poly amino-acids doesn't have stringent requirements on sequence or structure of the amino acid chain - a semirandom aa polymer can still have some catalytic activity to make more semi-random aa polymers.
Clumping random data is still clumped random data. You need to provide a method of a system of random data becoming functional.
This is not putting parts together to get a function. This is getting a function out of noise. Evolutionary software, or evolutionary examples of methods of progression never actually tackle the biogenesis problem: Data -> mechanism of translation -> function.
This could be DNA:RNA:Replication. It could be 100% RNA in RNA data: RNA folding: RNA replication. Or even your Random Amino acid configuration: Functional Amino Acid configuration: Replicating Amino Acid configuration.
But no matter how we frame the problem and solution, we need a 3 step process to get from one system (data) to another (a function, such as replication or metabolism, homeostasis etc).
Everybody forgets the "Fl" part of the Drake equation.
"Fl" means "planets per star that can support life". Whilst its great having all of the building blocks for life abundant throughout the universe, the conditions to support life is one of (if not THE) most critical elements.
Most of our observable locality is awash with DNA-destroying Ionising radiation and the one thing that stops all life on earth frying to death in the bath of radiation we're pummelled with every day is the lovely warm comforting blanket of the vast magnetic field we have around us.
That blanket is pretty unique in that it's so stable. You only have to look in our own back yard (solar system) to see that without a magnetic field life just cannot survive for long enough to develop and evolve to complex life.
Mars seems to have been rich in the building blocks for life in the past but with it's magnetic field it all came to nothing. The Moon Europa has a magnetic field and a lot of the building blocks for life right there. Surely the chance of complex life there (under the ice) hangs on whether that field is enough to sustain the relentless smash of radiation from Jupiter.
Maybe we need to stop looking for the building blocks and start looking for the signs of a stable magnetic field first?
Europa's magnetic field is about 200 times weaker than Earth's. That said, it's deep enough within mummy's magnetosphere that it's not got to worry about anything coming from the Sun.
But probably the most important function of the magnetosphere is not protection from radiation, but prevention of solar erosion of water from the atmosphere. Tardigrades (and D. radiodurans) might survive the radiation, but even they need water to live.
"But probably the most important function of the magnetosphere is not protection from radiation, but prevention of solar erosion of water from the atmosphere."
Water is a _very_ good radiation blanket (you can't detect the radiation from a running nuclear reactor a couple of metres away). Whilst the organic compounds necessary for life were probably formed in the atmosphere (there's a rather famous experiment replicating earth's early atmosphere complete with lightning that invariably results in the inside of the container being smeared with organic compounds), they will have rained out into the oceans - and life itself evolved in water, mostly well away from light (remember, the water was black due to all the dissolved iron) and probably mostly around hydrothermal vents - there's even a hypothesis that early archea took their shapes from micropockets in the rocks, then developed membranes, became free floating, got to the surface and discovered light.
Being in iron/copper/manganese/magnesium rich water would explain why these metals are at the core of so much bichemistry. The difference between haemoglobin (iron), haemocyanin (copper) and chlorophyll (mangnesium) is down to this.
Now bear in mind that when a gas cloud collapses to form a stellar disc the process is going to be much the same most places. Iron, carbon and water are amongst the most common materials in the universe (free oxygen will bind with anything it meets) so you can bet that any place life has an opportunity to form, it's likely to have those amongst the building blocks available.
The main thrust of the article - that the "building blocks for life" are fairly common throughout the galaxy - seems straightforward enough, but all the talk about white dwarf stars seems out of place.
A white dwarf star is a stellar remnant - it's what's left after a main sequence star has gone through its red giant phase, so if there had been life around the progenitor star i.e. before the red giant phase, it would either have had to leave or get fried.
Once the red giant has finally used all of its remaining fuel it will collapse to form a white dwarf, about the size of Earth but with a mass comparable to the Sun. It'll have no internal source of energy now though, and only radiate the thermal energy gained from its collapse, so once it has formed it will inexorably start to cool down and this is a problem for the subsequent development of new life because the habitable zone will change relatively quickly, in the order of a few billion years, so if life did develop it might not have very long to get used to it.
In addition, although white dwarf stars can start out to be very hot > 100,000K, their small size means that any habitable zone would have to be relatively close to the star, far closer than Earth, and quite likely to be close enough to be tidally locked.
Then there's the issue of where these closely orbiting planets have come from, following the red giant phase that would have entirely engulfed any existing planets in those regions.
I'm not saying that any of this can't happen, but white dwarf star systems seem an unlikely sort of place to look for life.
"I read them as saying that if the building blocks are common around white dwarves, they are probably common around other stars, and it's these other stars that might have life. They are not looking for or predicting life around white dwarves."
Yes, my impression is that they where using white dwarfs coz they are easier places to find the specific things they where looking for.
As mentioned, they are only looking for the "building blocks for life", not life itself, in order to hopefully then extrapolate that out to the rest of the universe.
White dwarfs give you a nice steady, predictable light/radiation source to make the analysis easier.
With all of humanity's resources and knowledge, we still have no theory that has convinced the scientific community of how life originated from natural processes. So we don't know the conditions required for life to form. That being so, I can't get very excited about the prospect of life existing elsewhere just because the building blocks are available.
Also on Earth it took a long time after the formation of simple life for complex life (cells with nuclei etc) to emerge, so that might not be a common occurrence even where there is some form of life. It's difficult to imagine intelligence without life more complex than bacteria.
It would be truly astonishing if Earth had the only form of complex life in the universe. But at the moment it seems very premature to think that we will find other life, and especially complex life capable of intelligence, near enough for us to detect.
Its entirely possible that the largest "intelligent" tool-using lifeform on an alien planet is the size of a mouse.
Different scale, their idea of a year might be radically altered and they would run through an entire lifetime in the blink of an eye from our point of view.
Judging by how smart even house mice are, saw one try to outrun a cat and fail miserably having outwitted it for a good half an hour it seems that to extrapolate something with the IQ of say a parrot isn't totally implausible and intelligence may actually be *more* efficient with a smaller brain using hyper-connectivity between the cortices which is an avenue unexplored in Terran biology.
It would be intriguing to take something with the ability for raw intelligence and use simple selective breeding and say a higher oxygen level (small change = large effect) in a small biosphere devoid of predators to see what happens.
Just why do scientists always think that elements for life on other planets has to consist of what we know about earth? Who'se to say life didn't evolve completely differently, with a different mixture of gases, and 'water' not as we know it. I can understand the habitable zone theory, but even then, couldn't life evolve to exist in much colder or hotter climates. It's a blinkered view, and proves it really is all theory and guesswork.
"Just why do scientists always think that elements for life on other planets has to consist of what we know about earth?"
They don't think that, it's just easier to peer at tiny dots in the sky and infer the things we know work than try to scratch our heads over things we don't know about, on these tiny bits of evidence.
Once we have studied how liquid sulfur works as the basis of life on Mercury, or whatever, then it'll be a lot easier to point telescopes at distant suns and figure out which of the planets we can't actually see could possibly support sulfur based life forms, based on flickering spectra of that sun.
Give the astroboffins their due, it's hard enough doing the science they are doing, without asking them to search for purely theoretical forms of life. The low hanging fruit is all we can reach for now.
Imagine, if you can, being God. All seeing. All knowing.
You can invent every dimension and craft physics to perfection - predict with 100% accuracy how every molecule in a wave a billion years from now will crash onto a rocky shore, yet still you will have doubts.
Is this it? Is there more than I can perceive? Am I missing something a lesser mind might more readily stumble upon?
Life is God's throw of the dice in a perfectly ordered universe, creating the conditions for an infinite variety of lifeforms to come about, and thus throw a banana skin in the predicted path of everything they touch.
Life is the only thing that has a choice. Everything else clings rigidly to the laws of physics, even quantum particles that seemingly defy logic, operate flawlessly in a branch of physics we have yet to mine, or perhaps more aptly a dimension we have yet to comprehend.
Life is God's muse and entertainment and sure as hell, he'd want more than just the one channel to watch.
Just because the building materials are common does not mean that its likely that they get put together in the particular (and as yet unknown) way necessary to form life. For all we know the exact events that must occur in order to cause them to come together to produce the "spark of life" may be almost impossibly unlikely to happen. There is only one Taj Mahal despite the fact that the building materials are not particularly uncommon!
The other thing we don't know is how long life is likely to exist on a planet, on average, since we don't have a single example of a complete cycle. If a complete life cycle is a tiny fraction of the total life of the galaxy, the probability of there existing two life-bearing planets *at the same time* diminishes.
It's not just the chemical composition but the ratio of water to land, what meteors have hit the planet, how many moons there are, the distance from the sun, the type of sun, the region of the galaxy the solar system is in, the type of core the planet has, what it's mass is and rate of spin, whether the planet wobbles, how stretched it's orbital path around the local sun is, and the distance from the sun etc etc.
When there is very little information to go on the best that can be done is to assume that the situation is average. In case of life on other planets that would tend to suggest that life is not very common, as the average planet with life on it, should have a very large moon, as a result of some early collision during it's formation.
Now it is possible that the only life we know about just happens to be on such a planet, but statistically it is not very likely.
And of course if we find life on Mars/Jupiter's Moons etc., we will then need to show it could not have originated on earth, to get our second reference point.
So while the cocktail ingredients may be common, the stirring is not.
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