# Oxford scientists say: Looks like no other intelligent life in whole universe (but keep looking)



## Extollager (Dec 19, 2020)

We're all alone: Oxford study says chance of intelligent life elsewhere very low | The Times of Israel


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## .matthew. (Dec 19, 2020)

"Very low" or "exceptionally rare" in what is basically an infinite universe doesn't mean much.

We've also known it was incredibly unlikely for some time now and am getting genuinely sick of scientists essentially getting paid for reciting the same theories that have been gone over dozens of times before. Get them to work for their money I say


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## Extollager (Dec 19, 2020)

I'll go on enjoying sf stories with civilizations on other planets, but I do think it's worthwhile occasionally to be reminded that there is no evidence for them and that such evidence as we do have is not favorable to their existence.  Similarly about ftl travel: I'll go on enjoying stories with warp drive, hyperspace, etc. and the wonderful journeys between stars that it makes possible, while remembering that it's not going to happen.

The Impossible Physics of Faster-Than-Light Travel (popularmechanics.com)


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## Matteo (Dec 20, 2020)

Bwah ha ha ha ha...this is just what we want you to think puny earthlings...


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## paranoid marvin (Dec 20, 2020)

I think that the two big issues here are 

A.intelligent life at the same time as us

B.the likelihood of contact between the two 

It's extremely unlikely that all of space is lifeless and that every single planet in the universe is a dead rock (or amalgamation of gasses). We  know that there are the building blocks of life 'out there' , so at some point in time somewhere in the galaxy , the right combination will have combined in the right way to produce some form of life. It may only be miroscopic, it may have died out millions of years ago, but I'm convinced that it is out there in some shape or form. I'm equally convinced that human beings will be around long enough to make any kind of meaningful contact with it outside of viewing it under a microscope.


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## RJM Corbet (Dec 20, 2020)

paranoid marvin said:


> It is extremely unlikely that all of space is lifeless


Why? It is extremely unlikely that life originated on Earth, is it not? It's taken as a  foregone thing, but the odds are huge. It didn't just _have_ to happen?


paranoid marvin said:


> I'm convinced that it is out there in some shape or form.


But why?


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## mosaix (Dec 20, 2020)

I was thinking about the development of intelligent life this morning. This is slightly off-topic (sorry @Extollager) but if Earth is the only place in the Universe to develop life (as some believe) it seems against the odds, to me, that the only example of life should also develop intelligent life.

Edit: The implication (if Earth is the only source of life) is that life tends towards intelligence.


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## RJM Corbet (Dec 20, 2020)

mosaix said:


> The implication (if Earth is the only source of life) is that life tends towards intelligence.


I'm rusty: the jump from bacteria to eukaryote is described by Nick Lane as literally a once and one time only sort of event.








						The Vital Question - Wikipedia
					






					en.m.wikipedia.org


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## mosaix (Dec 20, 2020)

RJM Corbet said:


> I'm rusty: the jump from bacteria to eukaryote is described by Nick Lane as literally a once in the whole lifetime of the universe probability sort of event.
> 
> 
> 
> ...



Interesting RJM. If that is true (once in the whole lifetime of the universe probability) then it would seem unlikely that the development of life on Earth is also a one-off event.


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## RJM Corbet (Dec 20, 2020)

mosaix said:


> Interesting RJM. If that is true (once in the whole lifetime of the universe probability) then it would seem unlikely that the development of life on Earth is also a one-off event.


Sorry @mosaix, I edited post to read 'once and one time only' -- I'm being very careful.

The abiogenesis of life is not impossible, as explained by Lane. He doesn't like deep smokers, but is more into some sort of shallower  spongy type of osmosis sort of thing.

I run out of my depth fast, lol ...


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## mosaix (Dec 20, 2020)

RJM Corbet said:


> Sorry mosaix, I edited post to read 'once and one time only' -- I'm being very careful.



Not a problem, RJM, if I understand correctly my point stands - it seems unlikely that the _only_ source of life in the universe is the _only_ source of intelligent life.


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## RJM Corbet (Dec 20, 2020)

mosaix said:


> Not a problem, RJM, if I understand correctly my point stands - it seems unlikely that the _only_ source of life in the universe is the _only_ source of intelligent life.


Double whammy


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## RJM Corbet (Dec 20, 2020)

Ok. So the abiogenesis of life is something that definitely has happened at least once in the universe upon the planet Earth. Somehow against all probability bacterial life, through immense odds, then made the jump to become eukaryotic.

It did happen and here we are. Monkeys and typewriters wrote the complete works of Shakespeare. Yes it did happen. It happened once. That does not mean that it is inevitable everywhere else all over the universe?


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## Danny McG (Dec 20, 2020)




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## RJM Corbet (Dec 20, 2020)

The odds of intelligent life in the universe are not inevitable -- it's statistically on scale of monkeys on typewriters, Imo ... but there are infinite copies of me out somewhere so ...


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## Vladd67 (Dec 20, 2020)

Population: None


> _It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there most be a finite number of inhabited worlds. And finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any person you may meet from time to time are merely the products of a deranged imagination._


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## paranoid marvin (Dec 20, 2020)

The reason that I think life of some form is possible is all down to percentages. We know it's possible because it's happened at least once. We know that some of the things that helped make life on this planet possible are also present away from our planet. We know that there are billions of planets out there that have existed for billions of years. And that's just in this universe; it's entirely possible that there are many other universes out there. And that's only in the plane of existence of which we are aware; there may be many others out there. Given the facts we know, added to the potential number of possibilities, the chances of it not happening at some point in some place other than Earth I find hard to accept.

Look at the catastrophes that our planet has suffered to get to this point, the number of events that have _almost_ wiped out life. But we know that it is persistent, it is resilient and (to quote a certain phrase from a certain movie) it _finds a way._

The moment we find any form of life - alive or dead - even the smallest microbe frozen in the waters of one of our solar system's moons, it will prove that some form of existence is possible. As I mentioned early, and given the distances involved, and given the size and length of time the universe has been in existence, it would surprise me that within the lifetime of the human race - which even if it lasts for 100,000 years is still only peanuts in relation to the age of the universe - we made contact with an alien lifeform with which we could make understandable conversation. But personally I think that sooner rather than later we will find some proof of life.


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## paranoid marvin (Dec 20, 2020)

Vladd67 said:


> Population: None



Douglas Adams by any chance?


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## Vladd67 (Dec 20, 2020)

paranoid marvin said:


> Douglas Adams by any chance?


Who else?


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## .matthew. (Dec 20, 2020)

I think it exists out there, or has, or will, or whatever.

I don't think we'll ever make contact or even find proof. Now, if we happen to discover some means of FTL travel then the odds go down and we might, but assuming that isn't the case, it means that even billions of years into the future, whatever humans have become (if we survive at all) will still occupy only the tiniest fraction of the universe.

I also wouldn't want to encounter another intelligent lifeform. We know that life is competitive and intelligent life voraciously so. It would be war.


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## RJM Corbet (Dec 21, 2020)

Imo for the universe to exist at all, a lot of one-off circumstances had to occur and in conjunction with each other: the electron proton charge exactly matches and the gravitational force is exactly as it is, etc. Several other conditions too.

These circumstances did occur in conjunction and so the universe does exist. But _because something happened once does not make it more likely to happen again -- much_ less make it inevitable -- unless we posit an infinite universe, in which case anything and everything not only does happen but happens an infinite number of times?


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## CupofJoe (Dec 21, 2020)

I'm all for an infinite universe. The more the merrier.
I'll settle for infinite realities. There is so much that we don't know and even more doesn't fit what we do know. One explanation may be other realities that coincide with some dimensions of our own but not all of them.


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## Guttersnipe (Dec 22, 2020)

Meanwhile, the Gwuds of the planet Seriquaan have come to the same conclusion.


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## .matthew. (Dec 22, 2020)

I don't have issue with infinite universes (because I have no idea how matter came to exist in the first place).

That said, I don't agree with the idea that realities branch with decisions made etc. I know it's a popular concept, but the idea of an infinite universe being created trillions of times a second seems too far fetched


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## Boneman (Dec 22, 2020)

Someone.... will find and post the Calvin and Hobbies cartoon where Calvin says:

"The surest sign that there's intelligent life in the Universe is that none of it has visited here " 

(IIRC he was looking at trash piled up in woodlands, but I could be wrong )


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## paranoid marvin (Dec 22, 2020)

RJM Corbet said:


> Imo for the universe to exist at all, a lot of one-off circumstances had to occur and in conjunction with each other: the electron proton charge exactly matches and the gravitational force is exactly as it is, etc. Several other conditions too.
> 
> These circumstances did occur in conjunction and so the universe does exist. But _because something happened once does not make it more likely to happen again -- much_ less make it inevitable -- unless we posit an infinite universe, in which case anything and everything not only does happen but happens an infinite number of times?




The thing is though that if something happens once it proves that it is not impossible; at best (or worst) it makes it highly improbable. It al comes down to how improbable. The more planets there are, the less improbable. The older the universe the less improbable. Given that there are trillions and trillions of planets out there, and that many have existed for billions and billions of years, the probability of life greatly improves.

 Personally I prefer to look at the number of opportunities there are for something to happen rather than the science that says when and how it can happen.


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## RJM Corbet (Dec 23, 2020)

paranoid marvin said:


> The thing is though that if something happens once it proves that it is not impossible; at best (or worst) it makes it highly improbable. It al comes down to how improbable. The more planets there are, the less improbable. The older the universe the less improbable. Given that there are trillions and trillions of planets out there, and that many have existed for billions and billions of years, the probability of life greatly improves.
> 
> Personally I prefer to look at the number of opportunities there are for something to happen rather than the science that says when and how it can happen.


Sure. But the fact is the abiogenesis of life is not a foregone conclusion. Even where the perfect conditions exist for it to happen, it's still like winning the lottery -- with numbers far higher than that. However it did happen so obviously yes it can happen.

But the odds of someone winning a lottery twice are greatly higher than winning it once.

The great problem though is the jump from bacterial to eukaryotic cells. It is regarded as virtually impossible, if anything even more unlikely then the  abiogenesis of life itself. So the jump from bacterial to intelligent life is a huge barrier.

Nick Lane"s 'The Vital Question' explains it carefully.

Again: it did happen, at least once. But neither abiogenesis nor the jump from bacterial to eukaryotic cells can just be assumed on the basis that the universe is very big. Imo

Of course, if it was _put_ there, but ... that can quickly push beyond the limits of the forum


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## Vertigo (Dec 23, 2020)

I'm in agreement with @RJM Corbet, there are just so many incredibly unlikely coincidences that have resulted ultimately with us. For example having a large enough moon to stabilise the tilt of the Earth's spin, its obliquity, which in turn stabilises potentially wild climatic fluctuations that would have made the evolution of complex life extremely unlikely. Earth's obliquity varies between around 22 and 24.5 degrees whereas for Mars "the maximum possible variation is from about 14.9 to 35.5 degrees. Significant climatic effects must be associated with the phenomenon." And there are so many more; volcanic activity, plate tectonics, Jupiter maybe shepherding asteroids, etc. etc. There will no doubt be many instances of many of these factors but how many times when they have all come together in perfect harmony?

Then for those that talk about the numbers, if you take our galaxy only a very small band is considered likely to be able to support complex life. Too close to the centre and the intense radiation would make mutation so chaotic that any sort of order evolving is extremely unlikely and too far out (as I understand it) there are too few heavier elements (down to what generation the stars are, I believe).

I think microbial life almost certainly exists elsewhere but chances of it making it past that stage is, I think, extremely small, and then to get beyond that to truly complex life (plants etc.) and then beyond that to animal life and finally to intelligent life (or maybe technological life might be a more meaningful description) is in my view vanishingly small. Taking just that last step for example, think how long Earth life was dominated by dinosaurs who showed no real signs of ever evolving technological intelligence, huge orders of magnitude greater than the evolution of humans. They just didn't need it they were already evolved to survive perfectly well without it. This to me says that there is no inevitable progress of complex life towards intelligence.


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## K. Riehl (Dec 23, 2020)

I'll stick with my belief that there is life out there. Billions of years and trillions of planets make for unlikely outcomes to have a chance at reaching the level of self awareness. 

I always throw out the possibility that the intelligent life in the universe is there and just using an as yet undiscovered method of communication.  The future may not be in exploration but in developing an Ansible that unlocks the the key to the Encyclopedia Galactica. ( to quote Contact)


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## Astro Pen (Dec 23, 2020)

It comes down to the likelihood of a first molecule of DNA cropping up. After that occurrence it is a free, if lengthy, ride to complex life and possible civilization. 
  I believe it was Onassis who said_ "Buying ships is easy, except for the first one."_


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## Vertigo (Dec 23, 2020)

Astro Pen said:


> It comes down to the likelihood of a first molecule of DNA cropping up. After that occurrence it is a free, if lengthy, ride to complex life and possible civilization.
> I believe it was Onassis who said_ "Buying ships is easy, except for the first one."_


DNA is just the program but you still need the computer before you can program it. So DNA is just one small cog in the machine. There are some fantastically complex molecules and processes going on in cells that make DNA look almost simple in comparison.


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## Extollager (Dec 23, 2020)

There's a good story to be written based on the theme of what happens when society generally realizes that there are ineluctable limits to achievement and knowledge.  SF tends to proceed on the basis of the idea, encouraged by our technological advances and astounding gains in knowledge, that (if nuclear war or, more recently, planetary overheating don't do us in first) the trajectory will continue till we have explored the whole galaxy and maybe more, have practical immortality, etc.; every seeming barrier, ever problem, can be overcome given time.

But in fact -- well, I start with this: for centuries there was, I gather, a tendency for the average person to get taller, century by century.  The cliche is the tourist looking at the suit of armor and thinking how small the wearer was, etc.  But we won't go on getting taller and taller, especially while living on earth.  Again, the record for running the mile may be improved, but it will not keep on being improved forever; at some point there will be a record set for running the mile that, 50 years or more later, no one has beaten.  

There's the assumption that human will live on other planets.  But I wonder.  Supposing civilization endures that long, say 300 years for now _will_ humans have traveled to Mars, even?  There's that matter of cosmic ray exposure.  I have no objection to stories that wave that away, as a problem that will be solved; but what if it is insoluble?  How will people adjust to the reality that we are not going to Mars, let alone to the stars (which has tremendous problems -- likely insoluble -- aside from cosmic ray exposure -- the oft-invoked suspended animation solution is, I suspect, a bigger problem than many people think).

And so on.  I wonder what it will be like to live on earth if, 300 years from now, or even by the end of this century, it has become clear that most of the science fiction assumptions were never going to be realized.

When I discovered Geoff Ryman's concept of "mundane sf" I felt I had discovered a kindred spirit.  But, again -- I'll go on enjoying stories with FTL travel, and gobs of Jack Vance colorful extraterrestrial civilizations and so on.  Sure, why not?  But for mental hygiene I think it's worthwhile also to bear in mind that none of it may ever happen, nothing like it.  In fact the evidence tends the other way.


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## RJM Corbet (Dec 23, 2020)

Extollager said:


> evidence tends the other way.


Yes. Science is often in the business of correcting _common goose sense intuition_. The atom is not a scaled down model of the solar system, etc. The biological organism is hugely complicated. Even a single cell is a mind-bogglingly astonishing symbiotic structure beyond all realistic coincidence. If regarded as a 'goal'. 

Again: the fact is that it _has_ originated once. Only once. All eukaryotic cells are descended from that one single original 'parent' cell.

So there can be no statistical probability drawn from a single occurrence. But of course that does not imply it will be a common occurrence, no matter how big the universe is?


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## Justin Swanton (Dec 23, 2020)

Vertigo said:


> DNA is just the program but you still need the computer before you can program it. So DNA is just one small cog in the machine. There are some fantastically complex molecules and processes going on in cells that make DNA look almost simple in comparison.


DNA is not actually the programme, it's the hard drive. The programme is the 4-base prescriptive language made of the nuceobases cytosine, guanine, adenine and thymine (our computer programming language has two bases). Without this 4-base programming language you don't have life. If you want an in-depth, scientific analysis of the statistical odds of such a programme arising spontaneously see *here* (spoiler: the odds would make the chances of life arising spontaneously on another planet utterly remote).

BTW we've had this discussion before, or maybe that was on the SFF World forum.


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## Vertigo (Dec 23, 2020)

Justin Swanton said:


> DNA is not actually the programme, it's the hard drive. The programme is the 4-base prescriptive language made of the nuceobases cytosine, guanine, adenine and thymine (our computer programming language has two bases). Without this 4-base programming language you don't have life. If you want an in-depth, scientific analysis of the statistical odds of such a programme arising spontaneously see *here*.
> 
> BTW we've had this discussion before, or maybe that was on the SFF World forum.


Yes, fair enough, that's probably a better analogy! But I'd still hold to the fact that I found some of the chemical processes at work in cells even more mind blowing than DNA the mechanisms for energy transfer are truly awesome. But I couldn't name them without going off and looking them up.


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## Justin Swanton (Dec 23, 2020)

Vertigo said:


> Yes, fair enough, that's probably a better analogy! But I'd still hold to the fact that I found some of the chemical processes at work in cells even more mind blowing than DNA the mechanisms for energy transfer are truly awesome. But I couldn't name them without going off and looking them up.


Sure, but keep in mind that that complexity - all of it - is contained in the ATGC prescriptive language in DNA. Everything is mapped out in advance in a series of instructions that are phenomenally dense, i.e. there is much, much more information in a gigabyte of DNA than an equivalent gigabyte on a PC hard drive. DNA uses complex palindromes: start in different places on the same segment of DNA and you get instructions for different and completely functional protein molecules. A bit like taking a long sentence, starting and ending in different places, and getting perfectly meaningful and completely different subsentences. We haven't begun to understand how it's done, but geneticists are looking at 'junk DNA' that isn't as useless as originally thought, but seems to contain sequential instructions for how and when sections of DNA are copied for transfer to the protein factories in a cell.


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## Extollager (Dec 23, 2020)

RJM Corbet said:


> So there can be no statistical probability drawn from a single occurrence.



I never thought of it that way (rolls eyes).


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## Extollager (Dec 23, 2020)

Extollager said:


> There's a good story to be written based on the theme of what happens when society generally realizes that there are ineluctable limits to achievement and knowledge.



Has anyone written that story, or something akin to it?

Another example of limits that's occurred to me is: suppose that we do, after all, detect signals that can only be from an extraterrestrial civilization.  (I don't expect that to happen, but let's suppose it does.)  These must be imagined as having arrived here after an enormous lapse of time.  How would society deal with it (which means various people deal with it) if it were obvious that we will _never_ be able to decode them?  We must assume that the signals are meaningful, but they will _never_ be meaningful to _us_?  SF people are (I think) apt to be naive about the difficulties of "translation" in the absence of a Rosetta Stone, etc.  And here you would have to factor in the time element.  I also have doubts about our ability to pinpoint the source, i.e. to say, "The signals are coming from a planet orbiting such and such a particular star," etc.  So we have signals about whose source we cannot attain definite knowledge and whose meaning must elude us.  Whew!


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## Justin Swanton (Dec 23, 2020)

Extollager said:


> Has anyone written that story, or something akin to it?
> 
> Another example of limits that's occurred to me is: suppose that we do, after all, detect signals that can only be from an extraterrestrial civilization.  (I don't expect that to happen, but let's suppose it does.)  These must be imagined as having arrived here after an enormous lapse of time.  How would society deal with it (which means various people deal with it) if it were obvious that we will _never_ be able to decode them?  We must assume that the signals are meaningful, but they will _never_ be meaningful to _us_?  SF people are (I think) apt to be naive about the difficulties of "translation" in the absence of a Rosetta Stone, etc.  And here you would have to factor in the time element.  I also have doubts about our ability to pinpoint the source, i.e. to say, "The signals are coming from a planet orbiting such and such a particular star," etc.  So we have signals about whose source we cannot attain definite knowledge and whose meaning must elude us.  Whew!



There's one problem with this. A signal that is strong enough to travel for thousands of light years without dissipating and getting lost against background cosmic radiation would require a phenomenally powerful transmitter, itself requiring an enormous energy source. There's no getting around it: any kind of broadcast will use some form of radiation, and radiation naturally spreads out and dissipates over a long distance. We can barely see, using powerful telescopes, the light from the more distant stars in our galaxy. But figure how massively powerful a transmitter of light a star is. How does a planetary civilisation manage - or even bother trying - to emit a comparable signal?

Edit: one presumes the alien civilisation would not transmit a focussed beam at one planetary system in particular, since they, like us, would not know in advance which planetary systems are inhabited. That means transmitting an omnidirectional signal which would require staggering amounts of power.


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## Vertigo (Dec 23, 2020)

Justin Swanton said:


> There's one problem with this. A signal that is strong enough to travel for thousands of light years without dissipating and getting lost against background cosmic radiation would require a phenomenally powerful transmitter, itself requiring an enormous energy source. There's no getting around it: any kind of broadcast will use some form of radiation, and radiation naturally spreads out and dissipates over a long distance. We can barely see, using powerful telescopes, the light from the more distant stars in our galaxy. But figure how massively powerful a transmitter of light a star is. How does a planetary civilisation manage - or even bother trying - to emit a comparable signal?
> 
> Edit: one presumes the alien civilisation would not transmit a focussed beam at one planetary system in particular, since they, like us, would not know in advance which planetary systems are inhabited. That means transmitting an omnidirectional signal which would require staggering amounts of power.


This has always been my argument against the picking up of alien signals. Our normal TV and radio signals would, so I understand, be almost undetectable beyond a few light days out certainly beyond light months out, unless as you say they were highly focused signals and how would anyone know where to focus them?


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## Extollager (Dec 23, 2020)

Vertigo and Justin, I don't remember ever considering those points.  Interesting.


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## Justin Swanton (Dec 23, 2020)

Vertigo said:


> This has always been my argument against the picking up of alien signals. Our normal TV and radio signals would, so I understand, be almost undetectable beyond a few light days out certainly beyond light months out, unless as you say they were highly focused signals and how would anyone know where to focus them?


I did some research on this for my own SF novel. The old Cold War military radars (which sometimes cost millions each to build) could transmit a signal detectable up to about 200 light years, but that beam could not contain any information like a radio or TV signal. It would just prove that its source was an intelligent civilisation. The galaxy has a diameter of 105 700 light years so, yeah, the radar isn't up to the job.


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## RJM Corbet (Dec 23, 2020)

Extollager said:


> I never thought of it that way (rolls eyes).


Along with the other common error of false equivalence: A happened, B also happened: therefore they are (casually) related?

"Once, it's happenstance. Twice, it's coincidence,: third time it's enemy action"
-- Al Capone


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## Vertigo (Dec 24, 2020)

Justin Swanton said:


> I did some research on this for my own SF novel. The old Cold War military radars (which sometimes cost millions each to build) could transmit a signal detectable up to about 200 light years, but that beam could not contain any information like a radio or TV signal. It would just prove that its source was an intelligent civilisation. The galaxy has a diameter of 105 700 light years so, yeah, the radar isn't up to the job.


Yes, I remember coming across something about that as well. There was also the fact that this was a highly directional/focused signal, though of course it would have swept across a significant part of the sky. But as you say no information and it was still only 200 light years with really doesn't cover very much space in real terms.


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## Astro Pen (Dec 24, 2020)

Vertigo said:


> Yes, I remember coming across something about that as well. There was also the fact that this was a highly directional/focused signal, though of course it would have swept across a significant part of the sky. But as you say no information and it was still only 200 light years with really doesn't cover very much space in real terms.


The catch 22 is that this also applies to all other sentient civilizations at our level or somewhat above it. Only a creme de la creme civilisation (to coin a phrase) will likely have the tech, if indeed the inverse square law doesn't kill that hope the same way that C limits travel.
I have thought for some time that robotic scouts carrying information will be the beast we meet. They remove the 'coincidence' imperative of transmitted signals. They can sit and wait. The Clarkian monoliths have it. 
Of course if they only wanted a 'flag', to show off,  arranging six stars in a perfect hexagon should do it.   (I'm writing that one.)


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## Vertigo (Dec 24, 2020)

Astro Pen said:


> The catch 22 is that this also applies to all other sentient civilizations at our level or somewhat above it. Only a creme de la creme civilisation (to coin a phrase) will likely have the tech, if indeed the inverse square law doesn't kill that hope the same way that C limits travel.
> I have thought for some time that robotic scouts carrying information will be the beast we meet. They remove the 'coincidence' imperative of transmitted signals. They can sit and wait. The Clarkian monoliths have it.
> Of course if they only wanted a 'flag', to show off,  arranging six stars in a perfect hexagon should do it.   (I'm writing that one.)


And, indeed, the two civilisations coinciding at the right time for both dispatch and receipt of any signals, bearing in mind the time delay. So a conversation of more than a couple of responses could take a thousand years or more! How convinced are we that we'll still be around in a thousand years!


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## Vladd67 (Dec 24, 2020)

Milky Way Is Probably Full Of Dead Alien Civilisations, Study Claims
					

<p>The Milky Way could be littered with dead alien civilisations, according to a new study. While scientists continue to try and get to the bottom of whether other life forms exist elsewhere, one theory says that they did, before killing themselves off. A group of three Caltech physicists and a...




					www.unilad.co.uk


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## Vertigo (Dec 24, 2020)

Vladd67 said:


> Milky Way Is Probably Full Of Dead Alien Civilisations, Study Claims
> 
> 
> <p>The Milky Way could be littered with dead alien civilisations, according to a new study. While scientists continue to try and get to the bottom of whether other life forms exist elsewhere, one theory says that they did, before killing themselves off. A group of three Caltech physicists and a...
> ...


That's interesting what they are saying about how earlier in the history of the galaxy life nearer the centre might have been more possible but then become less so as the galaxy moved towards it's peak of activity. Opportunities for a long story there of a civilisation migrating from the galactic centre towards the outer realm over millions of years!


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## Venusian Broon (Dec 24, 2020)

Vertigo said:


> I'm in agreement with @RJM Corbet, there are just so many incredibly unlikely coincidences that have resulted ultimately with us. For example having a large enough moon to stabilise the tilt of the Earth's spin, its obliquity, which in turn stabilises potentially wild climatic fluctuations that would have made the evolution of complex life extremely unlikely. Earth's obliquity varies between around 22 and 24.5 degrees whereas for Mars "the maximum possible variation is from about 14.9 to 35.5 degrees. Significant climatic effects must be associated with the phenomenon." And there are so many more; volcanic activity, plate tectonics, Jupiter maybe shepherding asteroids, etc. etc. There will no doubt be many instances of many of these factors but how many times when they have all come together in perfect harmony?



I think this is a bogus argument, I'm afraid. On another planet with different 'coincidences' that throw up thinking beings, they will go through a phase of arguments like this - that their random set of 'accidents' that made them are so rare, it is highly unlikely that this will be repeated elsewhere. 

Instead I think there will be quite a broad range of things that can happen that will still give rise to life. The old argument that the moon is vital for life to develop is a bit geocentric for me, other factors can stabilise planets tilts (an earth sized moon going around a water giant for example will be tidally locked) and perhaps for complex life a stable tilt really isn't needed. Who knows? Volcanic activity and plate tectonics is probably not that rare on the galactic and universal scale and the argument that Jupiter shepards us from asteriods is another old one that may not be correct - it may well have attracted more stuff into Earth orbit over time (May actually have been good for us, because perhaps the late heavy bombardment, likely caused by our big planets disturbing the young solar system, made the Earth what it is today) Again we don't really know. 




Vertigo said:


> Then for those that talk about the numbers, if you take our galaxy only a very small band is considered likely to be able to support complex life. Too close to the centre and the intense radiation would make mutation so chaotic that any sort of order evolving is extremely unlikely and too far out (as I understand it) there are too few heavier elements (down to what generation the stars are, I believe).



Again if you are attracted to finding 'Earths' and 'humans' then it narrows down choices, but other environments may be better suited for complex life that we've never come across, because, of course, the local galactic environment is what made us, us  



Vertigo said:


> I think microbial life almost certainly exists elsewhere but chances of it making it past that stage is, I think, extremely small, and then to get beyond that to truly complex life (plants etc.) and then beyond that to animal life and finally to intelligent life (or maybe technological life might be a more meaningful description) is in my view vanishingly small. Taking just that last step for example, think how long Earth life was dominated by dinosaurs who showed no real signs of ever evolving technological intelligence, huge orders of magnitude greater than the evolution of humans. They just didn't need it they were already evolved to survive perfectly well without it. This to me says that there is no inevitable progress of complex life towards intelligence.



I do agree with this, as we haven't see fossilised hand tools in the hands of dinos.  Also I do believe the step between bacteria level cells and eukaryotic ones is difficult as @RJM Corbet has pointed out (Bacteria are generally much more efficient cells, I believe, but I am no expert in the field!) and is/was probably a very big filter on the path to complex life. Hence my conjecture that life in the universe is really virtually all bacteria or similiar equivalents. (But probably virtually everywhere).


----------



## RJM Corbet (Dec 24, 2020)

Venusian Broon said:


> Hence my conjecture that life in the universe is really virtually all bacteria or similiar equivalents. (But probably virtually everywhere).


That would be fair enough, allowing what seems to be the standard narrative: that abiogenesis is common and pretty much inevitable wherever conditions are suitable -- deducing from the single fact that life exists on Earth?


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## Venusian Broon (Dec 24, 2020)

RJM Corbet said:


> That would be fair enough, allowing what seems to be the standard narrative: that abiogenesis is common and pretty much inevitable wherever conditions are suitable -- deducing from the single fact that life exists on Earth?


Technically my tentative hypothesis or scenario would sit on a whole bunch of known facts, not just one general statement. And rather than take the uniqueness of our planet as the central tenet, I would rather put my faith first in the Copernican principle and build on that a whole raft of observations of the universe we have made and our understanding of how matter, forces and energy interact with each other. 

But such a hypothesis would of course require evidence - for example simple life that has no connection with our biosphere may be present on certain bodies in our solar system, although trying to get a look at such life may be extremely difficult. I can imagine that simple single celled life could be deep in the rock crust of both Mars and Venus, as well as in the dark inner oceans of Europa. All such places extremely difficult to explore at the moment. Europa is our best bet, I feel, to try and find something wonderful. (And a bit easier to dig down into!  )


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## Brian G Turner (Dec 25, 2020)

RJM Corbet said:


> the jump from bacterial to eukaryotic cells. It is regarded as virtually impossible





RJM Corbet said:


> Only once. All eukaryotic cells are descended from that one single original 'parent' cell.



The biggest problem with discussion about the origins of life is that it all comes with an immense amount of bias. In the example of eukaryotes, biologists traditionally assumed there must be a simple and linear development of species from one to another - thus applying this logic backwards means that you end up with a single common ancestor of all complex life, which of course implies that this must only have happened once.

However, now we realize that when you get into the microbial world things become very complex quickly because microorganisms routinely share DNA. In other words, it becomes impossible to identify a single common ancestor of eukaryotes from microbes, because it's far more likely and scientifically plausible that a population of microbes spread over an area over a period of time may produce numerous different "common ancestors", all of which will share the same genes. Thus the entire question of "single common ancestor" becomes meaningless. And that's before we get into the further complexities of an "RNA world" origin for life.

The idea that the development of eukaryotes is unlikely or statistically impossible is another old-fashioned bias - we now know it happened at least 7 times for plants.

The worst bias is presuming that life is something so incredibly special that it cannot be replicated elsewhere in the universe. That is effectively a religious belief, and would be easily supported if life followed no scientific principles. However, that's not the case, and I would doubt many scientists would argue that any scientific principle works only in a single location of the universe to the exclusion of all others if the question was put that way.


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## RJM Corbet (Dec 25, 2020)

Brian G Turner said:


> The worst bias is presuming that life is something so incredibly special that it cannot be replicated elsewhere in the universe. That is effectively a religious belief, and would be easily supported if life followed no scientific principles.


This wouldn't be the place. It's not what I think, anyway.


Brian G Turner said:


> The biggest problem with discussion about the origins of life is that it all comes with an immense amount of bias.


And it works the other way too: because the universe is very big, it must be filled with life?


Brian G Turner said:


> we now know it happened at least 7 times for plants.


Thanks. That is interesting. Yes, my knowledge kind of stops at the single common ancestor, as does most of the discussion in this thread?
It would be interesting to learn a bit more here? 

EDIT
Quoting from Nick Lane (2015):

_"Life arose around half a billion years after the Earth’s formation, perhaps 4 billion years ago, but then got stuck at the bacteriological level of complexity for more than 2 billion years, half the age of the planet. Indeed bacteria have remained simple in their morphology (but not their biochemistry) throughout 4 billion years.

In stark contrast, all morphologically complex organisms – all plants, animals, fungi, seaweeds and single-celled ‘protists’ such as amoeba – descend from that single ancestor about 1.5 to 2 billion years ago.

This ancestor was recognisably a ‘modern cell’ with an exquisite internal structure and unprecedented molecular dynamism, all driven by sophisticated nanomachines encoded by thousands of new genes that are largely unknown in bacteria.

There are no surviving evolutionary intermediates, no ‘missing links’ to give any indication of how or why these complex traits arose, just an unexplained void between the morphological simplicity of bacteria and the awesome complexity of everything else. An evolutionary black hole."_

(That is on page two, and he goes on explaining the detail for another 300 pages.)

And from the OP article:








						We’re all alone: Oxford study says chance of intelligent life elsewhere very low
					

Paper uses statistics to examine how long it took life to evolve on Earth and how likely each step was; concludes highly unlikely other intelligent civilizations out there




					www.timesofisrael.com
				




_“Some transitions seem to have occurred only once in Earth’s history, suggesting a hypothesis reminiscent of Gould’s remark that if the ‘tape of life’ were to be rerun, ‘the chance becomes vanishingly small that anything like human intelligence’ would occur,” the paper says referring to the quote from evolutionary biologist Stephen Jay Gould._

apologies for all the editing ...


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## Venusian Broon (Dec 25, 2020)

Just a couple of points that made me search the internet to back up my feeble understanding of this topic  



RJM Corbet said:


> Thanks. That is interesting. Yes, my knowledge kind of stops at the single common ancestor, as does most of the discussion in this thread?
> It would be interesting to learn a bit more here?
> 
> _In stark contrast, all morphologically complex organisms – all plants, animals, fungi, seaweeds and single-celled ‘protists’ such as amoeba – descend from that single ancestor about 1.5 to 2 billion years ago._



I believe the author used the term "single ancestor" to make a fine sentence and hyperbole. Just to add to what Brian had stated, my understanding is that when an evolutionary biologist talks about the 'single ancestor' they technically mean the 'last universal common ancestor' which is the most recent _population_ of organisms from which all organisms living on Earth have a common descent. From the wikipedia article on the topic: "the last universal common ancestor is not thought to be the first life on Earth, but rather the only type of organism of its time to still have living descendants." And this can get quite complicated, as the position of this LUCA can legitimately move in time, not only from better knowledge, but as descendant branches die off.

This is a bit like mitochondrial Eve (or Y-Chromosonal Adam), which, again from wikipedia: 'The name "Mitochondrial Eve" alludes to biblical Eve, which has led to repeated misrepresentations or misconceptions in journalistic accounts on the topic. Popular science presentations of the topic usually point out such possible misconceptions by emphasizing the fact that the position of mt-MRCA is neither fixed in time (as the position of mt-MRCA moves forward in time as mitochondrial (mtDNA) lineages become extinct), nor does it refer to a "first woman", nor the only living female of her time, nor the first member of a "new species"'.





RJM Corbet said:


> _"Life arose around half a billion years after the Earth’s formation, perhaps 4 billion years ago..._



This appears to be an extremely 'safe' reading of the evidence. Other strands of evidence point to life possibly arising only a few hundred million years after Earth's formation, although 500 million years is, I believe, the point of time with the most conclusive geological evidence.




RJM Corbet said:


> _There are no surviving evolutionary intermediates, no ‘missing links’ to give any indication of how or why these complex traits arose, just an unexplained void between the morphological simplicity of bacteria and the awesome complexity of everything else. An evolutionary black hole."_



This was my understanding, although I would not have put it as an 'evolutionary black hole', as the leading hypothesis for their arrivial is via endosymbosis or 'A symbiotic relationship in which one cell resides within a larger cell" which is perhaps the ultimate in 'sharing' of material! Evolution in the Darwinian sense doesn't really apply to single celled organisms, as @Brian G Turner points out - we have identified a number of different mechanisms, such as the possibilty of endosymbosis, that would just not be trackable in the genetics through Darwinian evolution.

However the argument I read (a long time ago ) was that eukaryote cells were just incredibly inefficient in their cellular processes compared to standard bacteria, hence it is a struggle to work out how the first eukaryote cells ever survived against their bacterial competition.

I am very intrigued by @Brian G Turner's statement that "The idea that the development of eukaryotes is unlikely or statistically impossible is another old-fashioned bias - we now know it happened at least 7 times for plants." How can we know that it happened seven times for plants? Is this based on photosynthesis? As I do know that that process has developed/evolved a number of times independently, but I don't think current plants on the Earth can have seven different eukaryote 'fathers/mothers'. Don't all animal and plant cells share characteristics that point to one eukaryotic LUCA?


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## RJM Corbet (Dec 25, 2020)

Venusian Broon said:


> This appears to be an extremely 'safe' reading of the evidence. Other strands of evidence point to life possibly arising only a few hundred million years after Earth's formation, although 500 million years is, I believe, the point of time with the


I don't know VB. I'm listening to this guy. He goes into it in a very detailed and knowledgeable way.









						The Vital Question - Wikipedia
					






					en.m.wikipedia.org
				




@Vertigo recommended it, and it has greatly boosted my knowledge of the subject.



Venusian Broon said:


> believe the author used the term "single ancestor" to make a fine sentence and hyperbole.


No I don't think that's correct. I don't think anyone anywhere is really questioning Nick Lane's credentials and impartiality.

So the issue just seems to be whether any new knowledge has arrived around the LUCA since he published in 2015?


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## Brian G Turner (Dec 25, 2020)

RJM Corbet said:


> Life arose around half a billion years after the Earth’s formation, perhaps 4 billion years ago, but then got stuck at the bacteriological level of complexity for more than 2 billion years



The early atmosphere of the Earth would not support complex life, and in a few hundred million years it's unlikely to continue to do so. It's not a case of life being stuck as much as life can only evolve into the opportunities are available. Really, we live in a microbrial world and we complex forms are a temporary anomaly. 

Anyway, see if you find this of interest:








Venusian Broon said:


> "The idea that the development of eukaryotes is unlikely or statistically impossible is another old-fashioned bias - we now know it happened at least 7 times for plants."



Sorry, I think I may have confused things here. IIRC the argument for the emergence of eukaryotes is that - in a chance and statistically impossible encounter - one type of microbe was coopted to live inside another as mitochondria and ended up providing energy enough for complex development.

However, I've recently read that chloroplasts have been independently coopted by plants at least 7 times, which suggests this process of microbes being coopted shouldn't be regarded in statistically impossible terms. Unfortunately, I can't find my reference at the moment - is probably in one of my Kindle books notes.


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## Vertigo (Dec 25, 2020)

It is an excellent book isn't it @RJM Corbet, it was actually originally recommended by @Stephen Palmer.

The thing I struggle with it that there seem to be two arguments and I'm not sure which is the more improbable.

1. There was one singe ancestor cell. That can seem unlikely just by it's sheer uniqueness.

or

2. There were multiple ancestor cells. But that also seems unlikely as the surely the chances of multiple independently evolved cells having sufficiently similar chemistry to intermix is vanishingly improbable.

I tend to come down on the single ancestor as being the rather less implausible probability and being the simpler one a la Occam.

@Brian G Turner I'd love to see the research that about the 7 independent evolutions of eukaryotes in plants. See point two above; the idea that such a thing could happen independently and still be compatible just seems so unlikely to me. Event the earliest eukaryotes were fantastically complex pieces of biochemistry. (edit: @Brian G Turner gave the additional info above whilst I was typing!)


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## Venusian Broon (Dec 25, 2020)

RJM Corbet said:


> I don't think anyone anywhere is really questioning Nick Lane's credentials and impartiality.



Why not? He may just be wrong. I wouldn't question Einstein's credentials and impartiality but let's face it: he was wrong about Quantum mechanics.

Anyway, I fully admit that I've not read any of the book so I should stop trying to guess what he wrote, or what you are getting from the text, as my psychic powers are weak .

In my mind, there is indeed a 'single organism' somewhere in the mists of time that gives rise to everything today, which is essentially the LUCA concept...but when it was alive, I have no problems having it floating about with lots of very similar organisms. It's just that the direct 'offspring' of the rest of them have become extinct.



Vertigo said:


> 2. There were multiple ancestor cells. But that also seems unlikely as the surely the chances of multiple independently evolved cells having sufficiently similar chemistry to intermix is vanishingly improbable.



Surely though, if eukaryotes came about by endosymbosis then cells, bacteria and everything else was probably swapping loads of bits and pieces, some being subsumed whole etc. So everything kinda had similar chemistry? In fact it wouldn't matter if there were large 'phase spaces' of incompatibility between different organisms. Evolution would select the ones that did work well together and these new organisms with new advantages would compete well for resources and crowd out the less able older cells, no? Especially as single cell organisms could reproduce very quickly and exponentially.


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## Vertigo (Dec 25, 2020)

Venusian Broon said:


> Surely though, if eukaryotes came about by endosymbosis then cells, bacteria and everything else was probably swapping loads of bits and pieces, some being subsumed whole etc. So everything kinda had similar chemistry? In fact it wouldn't matter if there were large 'phase spaces' of incompatibility between different organisms. Evolution would select the ones that did work well together and these new organisms with new advantages would compete well for resources and crowd out the less able older cells, no? Especially as single cell organisms could reproduce very quickly and exponentially.


I think I'd go along with this at the level of the initial endosymbosis, after all all the prokaryotes are related, both bacteria and the archaea, but I suspect that level of flexible gene swapping dropped significantly with the first Eukaryote. The prokaryotes are all far more flexible than the eukaryotes but the latter support vastly more complexity. Bacteria have on average around 5000 genes whilst the eukaryotes have around 20,000 up to 40,000. 

However I confess I'm drifting so far out of my comfort zone here that I might be lying on a bed of nails!


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## RJM Corbet (Dec 25, 2020)

Vertigo said:


> is an excellent book isn't it @RJM Corbet, it was actually originally recommended by @Stephen Palmer.


Excellent imo. Thanks. I gave it away after reading it, but partly because of this discussion I  bought it again. Came next day. So now I need  to read it more carefully -- the original, singular,  primal one-off archaea,/bacteria absorption event -- in order to have my ducks in a row for discussions like this one, lol


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## RJM Corbet (Dec 26, 2020)

Brian G Turner said:


> The early atmosphere of the Earth would not support complex life, and in a few hundred million years it's unlikely to continue to do so. It's not a case of life being stuck as much as life can only evolve into the opportunities are available. Really, we live in a microbrial world and we complex forms are a temporary anomaly.


This is an interesting view. I think the  origin of eukaryotic cell predates the great oxygenation event?


Brian G Turner said:


> Anyway, see if you find this of interest:


Thank you. Those two guys rattle off like machine guns, lol 



Brian G Turner said:


> Sorry, I think I may have confused things here. IIRC the argument for the emergence of eukaryotes is that - in a chance and statistically impossible encounter - one type of microbe was coopted to live inside another as mitochondria and ended up providing energy enough for complex development ... suggests this process of microbes being coopted shouldn't be regarded in statistically impossible terms.


Late acquisition of mitochondria by a host with chimaeric prokaryotic ancestry
*Mitochondria latecomers to the eukaryote cell*

_"The eukaryote cell is so much larger and more complex than the cells of bacteria and archaea that it is hard to recreate the steps whereby it evolved. One current view is that the evolution of eukaryotes was triggered when an archaea-like cell accommodated the bacteria that went on to become mitochondria.

An alternative view is that eukaryotes were well on the way to their modern form before they acquired the bacteria that became mitochondria. This second view is supported by a study by Alexandros Pittis and Toni Gabaldón showing that mitochondrial genes are more closely similar to those of their supposed bacterial relations than many other eukaryote genes are to their own inferred prokaryote cousins. This result, which challenges current views, suggests that mitochondria were late additions to a eukaryote cell that was already evolving."_



Venusian Broon said:


> Surely though, if eukaryotes came about by endosymbosis then cells, bacteria and everything else was probably swapping loads of bits and pieces, some being subsumed whole etc. So everything kinda had similar chemistry? In fact it wouldn't matter if there were large 'phase spaces' of incompatibility between different organisms. Evolution would select the ones that did work well together and these new organisms with new advantages would compete well for resources and crowd out the less able older cells, no? Especially as single cell organisms could reproduce very quickly and exponentially.


I don't know if it applies, but Lane puts it down to energy availability per gene:

“ … eukaryotes have up to 200 000 times more energy per gene than prokaryotes … a chasm that explains … why the bacteria and archaea never evolved into complex eukaryotes, and why we are never likely to meet an alien composed of bacterial cells … in an energy landscape where peaks are high energy and troughs are low energy, bacteria sit at the bottom of the deepest trough, in an energy chasm whose walls stretch high into the sky, utterly unscalable. No wonder prokaryotes remained there for eternity …

… for bacteria, bigger is not better. On the contrary giant bacteria have 200  000 times_ less_ energy per gene than a eukaryote of the same size. Scaling up a bacterium … runs into a problem with surface-area-to-volume ratio.

… Imagine scaling up the size of a city 625 fold, with new schools, hospitals, shops, recycling centres and so on; the local government responsible for all these amenities can hardly be run on the same shoestring ..."

(So there was no energy need for prokaryotes to 'evolve')

Enough from me. Out of my depth ...


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## Stephen Palmer (Dec 26, 2020)

Those interested in the far-future possibilities of life on Earth would be interested in the excellent _The Life & Death of Planet Earth_ by Peter Douglas Ward and Donald Brownlee. Here's my review of it.


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## Wayne Mack (Dec 29, 2020)

Shoe by Gary Brookins and Susie MacNelly for December 27, 2020 | GoComics.com
					

View the comic strip for Shoe by cartoonist Gary Brookins and Susie MacNelly created December 27, 2020 available on GoComics.com




					www.gocomics.com


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## Justin Swanton (Dec 30, 2020)

Stephen Palmer said:


> Those interested in the far-future possibilities of life on Earth would be interested in the excellent _The Life & Death of Planet Earth_ by Peter Douglas Ward and Donald Brownlee. Here's my review of it.



My understanding is that half a billion years is about the limit life can survive on Earth, unless I'm missing something? I imagine a far future civilisation lingering at the tropical poles, a bit like the Homeworld humans on Karak.


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## Stephen Palmer (Dec 30, 2020)

Justin Swanton said:


> My understanding is that half a billion years is about the limit life can survive on Earth, unless I'm missing something? I imagine a far future civilisation lingering at the tropical poles, a bit like the Homeworld humans on Karak.



Yes, somewhere around that time scale, but it applies to multicellular life. Ward & Brownlee estimate 800 million years, but of course it's impossible to say. Bacterial and other forms of simple life will go on afterwards, but their time is limited by the average temperature of the planet, which, iirc, above about 50 degrees means only heat-loving Archaea can survive.
The time limit on animal life is also dependent on the amount of CO2 in the atmosphere. Once that is down to zero (via the Gaia positive/negative feedback processes) plant life collapses, which means most animal life will too because of food chains being founded essentially in plant life. CO2 levels reduce over long periods of time because the sun is slowly radiating more and more heat. Since life began on Earth, it's become 25% hotter. It was this realisation that helped James Lovelock develop the Gaia Theory.


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## BAYLOR (Dec 30, 2020)

Stephen Palmer said:


> Yes, somewhere around that time scale, but it applies to multicellular life. Ward & Brownlee estimate 800 million years, but of course it's impossible to say. Bacterial and other forms of simple life will go on afterwards, but their time is limited by the average temperature of the planet, which, iirc, above about 50 degrees means only heat-loving Archaea can survive.
> The time limit on animal life is also dependent on the amount of CO2 in the atmosphere. Once that is down to zero (via the Gaia positive/negative feedback processes) plant life collapses, which means most animal life will too because of food chains being founded essentially in plant life. CO2 levels reduce over long periods of time because the sun is slowly radiating more and more heat. Since life began on Earth, it's become 25% hotter. It was this realisation that helped James Lovelock develop the Gaia Theory.



In about a billion years , the sun will be 20  percent hotter and  Planet  Earth will become largely  inhospitable  to life and,  projecting further down that road , could end up becoming  a  second Venus.


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## Stephen Palmer (Dec 30, 2020)

Yes, that's about the size of it. Of course, evolution that far in the future could produce a few last surviving single-celled forms of life.


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## BAYLOR (Dec 30, 2020)

Stephen Palmer said:


> Yes, that's about the size of it. Of course, evolution that far in the future could produce a few last surviving single-celled forms of life.



On can hope that long before that  , man will have either long since left Earth for the stars  or , will have found  a way to move planet Earth away form the the sun and thus buy it more time.


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## paranoid marvin (Dec 30, 2020)

BAYLOR said:


> On can hope that long before that  , man will have either long since left Earth for the stars  or , will have found  a way to move planet Earth away form the the sun and thus buy it more time.



If we haven't , then there is no way we will survive that long. Since the advent of the atomic weapons, we have barely survived the last half century.


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## paranoid marvin (Dec 30, 2020)

paranoid marvin said:


> If we haven't , then there is no way we will survive that long. Since the advent of the atomic weapons, we have barely survived the last half century.



Which probably sounds more negative than I meant! But for lots of different reasons, whether it be a natural disaster from space or from Earth , a man-made act or simply the exhaustion of resources, we only have a pretty limited time to branch out from our planet. Couple of thousand years perhaps but certainly not much more than that. Which should still be ample time to do something about it. There's no reason why within the next couple of hundred years that we can't have settlements on the Moon.


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## K. Riehl (Dec 30, 2020)

Most of these theories presume life developing the way it did on Earth

What if it Silicon based? Possibility of Silicon-Based Life Grows - Astrobiology Magazine

What if the building blocks of life can develop in space? https://economictimes.indiatimes.co...locks-of-life-found-in-comet-by-nasa-research

What if the center of the galaxy has a greater chance at development of life due to higher cosmic ray effects? How cosmic rays may have shaped life

What if life develops on Radiation as a source of energy ? Could Life Thrive on Radiation? Scientists Say It’s Possible

Last but not least, we have only developed Radar, Radio and Radio Telescopes, Laser and fiber optics in the last 100 years. Why couldn't we develop or discover something new in the areas of communication in the next 200 years? Yes, I am an optimist.


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## Vertigo (Dec 31, 2020)

K. Riehl said:


> Most of these theories presume life developing the way it did on Earth
> 
> What if it Silicon based? Possibility of Silicon-Based Life Grows - Astrobiology Magazine
> 
> ...


Silicon based life implies using silicon instead of carbon to form the long chain molecules. This paper has only shown that we can force silicon to be _incorporated _in carbon based molecules not replace the carbon in them. "scientists have for the first time shown that nature can evolve to incorporate silicon into carbon-based molecules" and "This does not prove that silicon- or organosilicon-based life is possible, but shows that life could be persuaded to incorporate silicon into its basic components. " Now that shows that it is theoretically possible but it is, I believe, going to be far less efficient or flexible and, combined with the fact that carbon is far more abundant in the universe (nearly 8 times more common than silicon, I believe), it seems highly unlikely, though I'll concede not impossible, for silicon based life to out compete carbon based life.

We have long known that the "building blocks of life" or organic compounds can form in space. However there is a vast gulf between those building blocks forming and life itself forming. If you have some carbon and oxygen it does not automatically follow that you have a fire just the potential for it in the right conditions.

Mutation is essential to evolution and no doubt cosmic rays have had some impact on those mutations but there must also be some stability. If everything is mutating constantly then stable life is going to be highly unlikely. I would still contend that excessive mutation is likely to be the case closer to the galactic centre. Some mutation is good, too much mutation is bad.

Ultimately anything is possible but when dealing with something that evolves randomly over millions of years you need to look at what is most likely to happen. Whatever that is it is likely to dominate.

We have pretty much all of the components mentioned available right here within the solar system and yet, so far, have found no evidence of any other life than our own within the solar system. That's not to say it isn't out there but the longer we keep looking and not finding it the less likely it is. If I was arriving in the solar system for the first time it would be incredibly easy to spot the life on Earth it is incredibly obvious but if there is any other life then it is so hard to spot it must be far less abundant, with the possible exception of life in the atmospheres of the gas giants. That might be hard to spot and yet be very abundant. I have never denied that other life might exist but the more elusive it appears to be the less likely it is to be.


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## RJM Corbet (Dec 31, 2020)

K. Riehl said:


> What if it Silicon based? Possibility of Silicon-Based Life Grows - Astrobiology Magazine


It comes round again to the fact that the origination of carbon based life was not a simple or definite thing. Assuming carbon life is the 'easiest' form of life, the difficulties for silicon based life originating are multiplied. Which does not mean impossible. Perhaps some sorts of silicon based bacteria things do exist out there somewhere, but the chance of them ever progressing to become more complex is also greatly reduced.


K. Riehl said:


> What if the building blocks of life can develop in space? https://economictimes.indiatimes.co...locks-of-life-found-in-comet-by-nasa-research


This is acknowledged. The difficult part is the process of the building blocks combining in exactly the right way to become animated. Again, not impossible. But assuming that life was never the GOAL of the universe, there is no way of assuming that, because the blocks exist, they will assemble themselves?


K. Riehl said:


> What if the center of the galaxy has a greater chance at development of life due to higher cosmic ray effects? How cosmic rays may have shaped life
> 
> What if life develops on Radiation as a source of energy ? Could Life Thrive on Radiation? Scientists Say It’s Possible


Cosmic rays may have been part of the combination that enabled abiogenesis of life on Earth. If so, they could obviously also be a part of abiogenesis elsewhere? Of course, once life has come into being, all bets are off. Life is amazingly resilient and inventive.

EDIT
Post landed at the same time with @Vertigo's


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## paranoid marvin (Dec 31, 2020)

Vertigo said:


> Silicon based life implies using silicon instead of carbon to form the long chain molecules. This paper has only shown that we can force silicon to be _incorporated _in carbon based molecules not replace the carbon in them. "scientists have for the first time shown that nature can evolve to incorporate silicon into carbon-based molecules" and "This does not prove that silicon- or organosilicon-based life is possible, but shows that life could be persuaded to incorporate silicon into its basic components. " Now that shows that it is theoretically possible but it is, I believe, going to be far less efficient or flexible and, combined with the fact that carbon is far more abundant in the universe (nearly 8 times more common than silicon, I believe), it seems highly unlikely, though I'll concede not impossible, for silicon based life to out compete carbon based life.
> 
> We have long known that the "building blocks of life" or organic compounds can form in space. However there is a vast gulf between those building blocks forming and life itself forming. If you have some carbon and oxygen it does not automatically follow that you have a fire just the potential for it in the right conditions.
> 
> ...



Yes it would be almost impossible NOT to notice life on Earth, and as you say any life within our own solar system becomes more remote by the day. It was less than a century ago when people really thought that there could be canals on Mars or tropical rainforests on Venus, and that was with more than 1000 years of knowledge and quite sophisticated equipment.

Given the likelihood of water on certain moons in our solar system, it would surprise me if we didn't find some organisms of life there. Regardless of other factors, I feel that the presence of water is one of the key factors of life. And if there is water in several places in our solar system, we can only assume that it is likely to be abundant thoughout the universe. But what we know changes, and in the next 100 years it is entirely possible that much of what we know is true for Earth maybe entirely different for other places out there.


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## Vertigo (Dec 31, 2020)

Sir Patrick Moore was a great believer of life on Mars right up until the first landing or at least the first orbital images, I think.

I agree that it is more than possible there might be microbial life where liquid water is present on some of the moons in the solar system. Although water is not the only prerequisite. And it is highly likely that water is in abundance throughout the universe since hydrogen and oxygen (and carbon) are two (three) of the most commonly found elements. I think the most common four elements are hydrogen, helium, oxygen and carbon.


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## paranoid marvin (Dec 31, 2020)

RJM Corbet said:


> It comes round again to the fact that the origination of carbon based life was not a simple or definite thing. Assuming carbon life is the 'easiest' form of life, the difficulties for silicon based life originating are multiplied. Which does not mean impossible. Perhaps some sorts of silicon based bacteria things do exist out there somewhere, but the chance of them ever progressing to become more complex is also greatly reduced.
> 
> This is acknowledged. The difficult part is the process of the building blocks combining in exactly the right way to become animated. Again, not impossible. But assuming that life was never the GOAL of the universe, there is no way of assuming that, because the blocks exist, they will assemble themselves?
> 
> ...



Yes, once something has been proven as not impossible - as we ourselves are evidence - it all comes down to the chance of it happening again.

We have seen on Earth how technically beautiful and inventive nature can be. We have seen in space how beautiful and varied is the night sky. In a Universe teeming with  stars and planets, moons and comets,  quasars and blackholes, dark matter and antimatter and all manner of other things yet to be discovered, it would be a shame if only the inhabitants of one insignificant little planet in a far corner of the galaxy could have any appreciation for the aesthetics of it all.


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## Vertigo (Dec 31, 2020)

paranoid marvin said:


> Yes, once something has been proven as not impossible - as we ourselves are evidence - it all comes down to the chance of it happening again.
> 
> We have seen on Earth how technically beautiful and inventive nature can be. We have seen in space how beautiful and varied is the night sky. In a Universe teeming with  stars and planets, moons and comets,  quasars and blackholes, dark matter and antimatter and all manner of other things yet to be discovered, it would be a shame if only the inhabitants of one insignificant little planet in a far corner of the galaxy could have any appreciation for the aesthetics of it all.


It would indeed be a shame, but that's one of the things that worries me. I wonder how much of the speculation on other life, or at least other intelligent/technological life is just wishful thinking, combined with showing that something is possible and then extrapolating that in such a vast universe it is therefore inevitable.


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## paranoid marvin (Dec 31, 2020)

Vertigo said:


> It would indeed be a shame, but that's one of the things that worries me. I wonder how much of the speculation on other life, or at least other intelligent/technological life is just wishful thinking, combined with showing that something is possible and then extrapolating that in such a vast universe it is therefore inevitable.




I agree, but - for want of a better word - _nature_ largely does things that make sense and it also seems to promote and support life. If the nature of the universe is seen in microcosm on Earth then we are truly not alone. I find it hard to accept that the rest of the universe is filled with dead balls of rock and gas, but as you say part of that is down to be wishing it not to be so.


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## K. Riehl (Dec 31, 2020)

This is all true, as far as we understand how life developed here on Earth. Maybe conditions at center of the galaxy are so radically different that life found a different way to develop. Maybe they exist on radiation and consider the cold outer regions of the galaxy as unable to have developed life because there isn't enough radiation to maintain life as they know it. 

We use spectroscopy to figure out things about suns but we have almost zero information about planets.  Maybe the next couple of improvements in technology will allow us to directly observe planets and then we will know but until then we really don't know.

How can we make universal assumptions based on the sample size of one solar system?  If we lived in Antarctica and had no knowledge of the rest of the Earth  wouldn't we believe that life was rare and subzero temperatures were normal. How would we imagine the jungles on the equator?

The universe is vast and over a time period of billions of years even the rare event such as the spark of life may have happened millions of times.

I still prefer to be optimistic about life elsewhere. The tipping point will be when we can directly observe plants existing in the Goldilocks zone. Then my hopes can crushed or thrilled with the discovery.


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## paranoid marvin (Dec 31, 2020)

K. Riehl said:


> This is all true, as far as we understand how life developed here on Earth. Maybe conditions at center of the galaxy are so radically different that life found a different way to develop. Maybe they exist on radiation and consider the cold outer regions of the galaxy as unable to have developed life because there isn't enough radiation to maintain life as they know it.
> 
> We use spectroscopy to figure out things about suns but we have almost zero information about planets.  Maybe the next couple of improvements in technology will allow us to directly observe planets and then we will know but until then we really don't know.
> 
> ...




Some good points. What we know is all based on how things are here on Earth; that is the only basis we have. What we know to be undoubtable fact as changed over time, dependant on the progress of science. Who is to say (similar to what Douglas Adams suggested) that there aren't microscopic worlds out there inhabited by intelligent civilisations that could exist on the head of a pin? Which on the face of it, in intergalactic terms is what the size of our world is in comparison to the size of the universe (or perhaps even multiverse).

I understand that oxygen was originally poisonous to humans, but over time we adapted to the extent that we now absolutely rely upon it. Who is to say that extreme heat or cold or radioactivity is conducive to life in other parts of the universe, and that those looking from afar at our world would see the oxygen-filled atmosphere as making life impossible on our planet, just as we see the atmosphere of Venus making life impossible.


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## RJM Corbet (Dec 31, 2020)

paranoid marvin said:


> it would be a shame if only the inhabitants of one insignificant little planet in a far corner of the galaxy could have any appreciation for the aesthetics of it all.


It would also make man the highest intelligence in the universe ...


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## Vertigo (Dec 31, 2020)

paranoid marvin said:


> I understand that oxygen was originally poisonous to humans, but over time we adapted to the extent that we now absolutely rely upon it.


I'm sorry, but I don't believe that has ever been true other than that breathing pure oxygen is dangerous and quite toxic. However I don't believe there has ever been any mammal on Earth for whom oxygen has been poisonous rather than essential. In fact, until recently, I don't think we have ever known of any animals that don't need oxygen to survive. There are a couple of microscopic animals found recently that may not need oxygen.


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## paranoid marvin (Jan 1, 2021)

Vertigo said:


> I'm sorry, but I don't believe that has ever been true other than that breathing pure oxygen is dangerous and quite toxic. However I don't believe there has ever been any mammal on Earth for whom oxygen has been poisonous rather than essential. In fact, until recently, I don't think we have ever known of any animals that don't need oxygen to survive. There are a couple of microscopic animals found recently that may not need oxygen.



Ah, I may have this wrong then. My understanding was that our bodies had to adapt to breathing an oxygen-rich atmosphere, and that initially it was harmful rather than essential. It sounds like I might be confusing it with pure oxygen.


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## K. Riehl (Jan 2, 2021)

"The finding is the latest in a series of discoveries, over the past several years, pointing to the possibility that DNA and its close chemical cousin RNA arose together as products of similar chemical reactions, and that the first self-replicating molecules--the first life forms on Earth--were mixes of the two."









						Discovery boosts theory that life on Earth arose from RNA-DNA mix
					

Chemists at Scripps Research have made a discovery that supports a surprising new view of how life originated on our planet. In a study published in the chemistry journal <i>Angewandte Chemie</i>, they demonstrated that a simple compound called diamidophosphate (DAP), which was plausibly present...



					www.eurekalert.org


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## RJM Corbet (Jan 3, 2021)

K. Riehl said:


> "The finding is the latest in a series of discoveries, over the past several years, pointing to the possibility that DNA and its close chemical cousin RNA arose together as products of similar chemical reactions, and that the first self-replicating molecules--the first life forms on Earth--were mixes of the two."
> 
> 
> 
> ...


Did DNA come before or after the LUCA?





__





						Origin and Evolution of DNA and DNA Replication Machineries - Madame Curie Bioscience Database - NCBI Bookshelf
					





					www.ncbi.nlm.nih.gov
				




_"… Figure 6 illustrates two scenarios for the viral origin of cellular DNA replication proteins. In the first case (hypotheses 5), all DNA replication proteins originated from viruses, after the separation of the archaeal and bacterial lineages, in agreement with an RNA based LUCA, whereas in the other (hypothesis 4-5) a first transfer occurred before LUCA, and a second one occurred in the bacterial branch (post-LUCA) …"_

Did Eukaryotes come after Prokaryotes, or did they develop alongside one another?

(I don't pretend to closely follow all of the content of the article linked above. I have just pulled out the paragraph that came up outlined in response to my google query: Did DNA come before or after LUCA)

prokaryote / procariote.

_“ … Most prokaryotes carry a small amount of genetic material in the form of a single molecule, or chromosome, of circular DNA. The DNA in prokaryotes is contained in a central area of the cell called the nucleoid, which is not surrounded by a nuclear membrane. Many prokaryotes also carry small, circular DNA molecules called plasmids, which are distinct from the chromosomal DNA and can provide genetic advantages in specific environments.”_


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## Vertigo (Jan 3, 2021)

Coming a back a bit closer to the original post, the UK based amongst us might be interested in this new Attenborough series starting tonight (3rd Jan) on BBC1 at 2000. Don't know about other countries, I'm afraid, probably at a later date.








						BBC One - A Perfect Planet
					

Exploring the great forces of nature that support, drive and enable life on earth.




					www.bbc.co.uk
				



The first episode is about how life needed volcanoes to evolve:


> A look at how without volcanoes, there would be no life on Earth. Although destructive, magma from the planet’s molten core builds land, and mineral-rich ash from eruptions fertilises the surface.


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## Vertigo (Jan 3, 2021)

RJM Corbet said:


> Did DNA come before or after the LUCA?
> 
> 
> 
> ...


As I understand it eukaryotes evolved from prokaryotes, in particular from the symbioses of a bacterium and an archaeon (the two domains of prokaryotes).


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## RJM Corbet (Jan 3, 2021)

Vertigo said:


> As I understand it eukaryotes evolved from prokaryotes, in particular from the symbioses of a bacterium and an archaeon (the two domains of prokaryotes).


That's how I understand it too. It seems to be the general understanding? But when does RNA/DNA enter the picture?





__





						Origin and Evolution of DNA and DNA Replication Machineries - Madame Curie Bioscience Database - NCBI Bookshelf
					





					www.ncbi.nlm.nih.gov
				




"We are reasonably sure now that DNA and DNA replication mechanisms appeared late in early life history, and that DNA originated from RNA in an RNA/protein world. The origin and evolution of DNA replication mechanisms thus occurred at a critical period of life evolution that encompasses the late RNA world and the emergence of the Last Universal Cellular Ancestor (LUCA) to the present three domains of life (_Eukarya, Bacteria_ and _Archaea)"_


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## J Riff (Jan 3, 2021)

dark ages continue.... )


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## Matteo (Jan 3, 2021)

Vertigo said:


> Coming a back a bit closer to the original post, the UK based amongst us might be interested in this new Attenborough series starting tonight (3rd Jan) on BBC1 at 2000. Don't know about other countries, I'm afraid, probably at a later date.
> 
> 
> 
> ...


Thanks! Had missed this. Will be tuning in.


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## Vertigo (Jan 3, 2021)

Matteo said:


> Thanks! Had missed this. Will be tuning in.


Me too. I only heard it being mentioned on the radio in the car yesterday!


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## Mike J Nagle (Mar 1, 2021)

Extollager said:


> We're all alone: Oxford study says chance of intelligent life elsewhere very low | The Times of Israel



Ahem.

What did Oxford say about the chance of intelligent life here?

If we ever find intelligent life, we probably won't recognize it,. Because we aren't.

'Nuff said,

Mike


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## Ursa major (Mar 1, 2021)

I think those Oxford University scientists were actually suggesting that there was no intelligent life at Cambridge University....


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## BigBadBob141 (Mar 5, 2021)

To paraphrase a song by Monty Python from their film "The Meaning Of Life".
Let's hope there's intelligent life out there.
'Cause there's b****r all here on Earth!


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