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

[Extollager]

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

 

[Justin Swanton]

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.

 

[RJM Corbet]

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

 

[Vertigo]

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.

 

[Astro Pen]

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.)

 

[Vertigo]

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!

 

[Vladd67]

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

 

[Vertigo]

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

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!

 

[Venusian Broon]

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.

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

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]

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?

 

[Venusian Broon]

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! )

 

[Brian G Turner]

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

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.

 

[RJM Corbet]

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.

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?

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 ...

 

[Venusian Broon]

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

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"'.

"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.

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?

 

[RJM Corbet]

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.

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?

 

[Brian G Turner]

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:

"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.

 

[Vertigo]

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!)

 

[Venusian Broon]

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.

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.

 

[Vertigo]

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!

 

[RJM Corbet]

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