Could Earth Be The Last Planet With Life In The Whole Universe?

tagemoss

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#1
Decided to put on the tin foil and speculate about a load of tosh...

While sleeping recently i was thinking, is the reason why we have so many different cultures on this planet because of evolution or something else?

That something else being? i donno....maybe each culture came from their own planet out there but some distaster ruined all those worlds and some alien race saw this distaster coming and saved a bit of each and planted them all here on earth which happened to be at the center of the universe (i know bs, rubbish etc) they themselves then died out, leaving only humans.

Their remains are now buried under maybe the north or south pole ice or somewhere on the planet....which we will find one day.

All the planets scientists have discovered that look like earth are long dead ?

sounds like a movie plot no ?
 

EnolaGaia

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#4
If earth's human population is comprised of the last survivors from different planets, how does one explain the uniformity of genomic structure across all cultures?

Even if one assumes RNA / DNA is the only workable or possible genetic material, how can one assume the number and arrangement of (e.g.) chromosomes / genes is somehow universal?
 

Xanatic*

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#5
It might be that Mars was once full of life, some of which ended up being spread to Earth via meteorites.

The universe has a temperature right now of about 3 degrees above absolute zero. It used to be much warmer, once apparently warm enough for liquid water. It could be the universe was teeming with life then and we are now in the era of the universe where it is so cold life has to huddle around stars for warmth.
 

Mythopoeika

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#6
It might be that Mars was once full of life, some of which ended up being spread to Earth via meteorites.

The universe has a temperature right now of about 3 degrees above absolute zero. It used to be much warmer, once apparently warm enough for liquid water. It could be the universe was teeming with life then and we are now in the era of the universe where it is so cold life has to huddle around stars for warmth.
Yep, we're in the heat death phase.
 

PeteByrdie

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#7
If earth's human population is comprised of the last survivors from different planets, how does one explain the uniformity of genomic structure across all cultures?

Even if one assumes RNA / DNA is the only workable or possible genetic material, how can one assume the number and arrangement of (e.g.) chromosomes / genes is somehow universal?
I understood the OP's idea as being that we're not the literal descendants of aliens, but their cultural descendants. So, we're a bunch of ape derived primitives swanning about this relatively inhabitable rock, and alien beings arrive from dying cultures, probably unable to actually survive on our world (so it's not worth simply living here), and it becomes their project to instill elements of their cultures in us. That way their cultures survive and evolve. It's a stretch, obviously. But a fun idea to play around with. Perhaps serpent people in Greek myth, for example Cecrops, were actual serpent like aliens, who had some kind of palace based civilisation on Alpha Centauri which they recreated in Greece. Given the number of dangerous serpent monsters in Egyptian mythology, maybe they were the enemies of the aliens who created Egypt. Perhaps South America was civilised by intelligent theropods from an alternative version of Earth where dinosaurs continued to evolve for millions of years, thence came Quetzalcoatl, the plumed serpent. I'm sure a multitude of myths could be shoehorned in for a bit of fun. To some degree, Stargate SG1 fooled about with such things, of course.
 

EnolaGaia

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#8
I understood the OP's idea as being that we're not the literal descendants of aliens, but their cultural descendants. So, we're a bunch of ape derived primitives swanning about this relatively inhabitable rock, and alien beings arrive from dying cultures, probably unable to actually survive on our world (so it's not worth simply living here), and it becomes their project to instill elements of their cultures in us. That way their cultures survive and evolve. ...
That interpretation occurred to me, but I couldn't see imparting a variety of alien cultural mores and motifs on a single species as a sensible strategy. It would be like writing on water - i.e., there'd be little chance of any culture's unique characteristics surviving intact.

In any case ... The apparent diversity of human cultures lies in the details, not in the basics. All human cultures are variations / elaborations on a set of common themes and requirements. If geographically separated human populations had been invested (infested?) with elements of diverse alien cultures we monkey-folk have done a grand job of blending them into a surprisingly uniform stew.
 

PeteByrdie

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#9
That interpretation occurred to me, but I couldn't see imparting a variety of alien cultural mores and motifs on a single species as a sensible strategy. It would be like writing on water - i.e., there'd be little chance of any culture's unique characteristics surviving intact.

In any case ... The apparent diversity of human cultures lies in the details, not in the basics. All human cultures are variations / elaborations on a set of common themes and requirements. If geographically separated human populations had been invested (infested?) with elements of diverse alien cultures we monkey-folk have done a grand job of blending them into a surprisingly uniform stew.
Yeah, the whole thing collapses under very casual scrutiny. Good for a science fiction story, but not as anthropological theory. The origins, disseminations and evolution of human cultures are now understood to the point that there are few gaps ripe for von danikening. I still like to play with alternative histories in my thought-box, though.
 

PeteByrdie

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#11
Here's a scary though - this is the refuge planet after we knackered our old one.
Another good science fiction idea. But, again, we clearly share our DNA with the rest of life on Earth. So we must have brought that too, which doesn't really tally with the billions of years of life on our planet. Nor does it withstand the known prehistory and history of the cultures on Earth, which have only recently reached beyond our atmosphere, having shown little knowledge of space travel previously.

Has there ever been a sci-fi story in which it's discovered that Noah's ark was actually a space ark from Mars carrying people and animals to Earth?
 

Ermintruder

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#15
But, again, we clearly share our DNA with the rest of life on Earth.
As @EnolaGaia also states.

But how do we know that DNA karyotypes are NOT inevitabilities?

That is (attuned to, one might say, the 'Hollywood take' on this) that viable sentient alien life perhaps can only ever possess a convergent set of parallel-evolved genes, and thus are homeomorphic with us in almost all respects. Mammals:Marsupials.....
Earth Primates:Alien Primates
 

Xanatic*

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#16
It could well be alien genes have the same letters but they won't have the same words. Besides, we even have the same typos in the words as other earth animals.
 

EnolaGaia

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#17
... But how do we know that DNA karyotypes are NOT inevitabilities? ...
For starters ... Because DNA itself is not inevitable (i.e., a chemically unique means for genetic encoding / transmission).

Modifying DNA / RNA into alternative polymers with the same essential structures and capabilities (and even higher stability) was accomplished years ago ...
DNA alternative created by scientists

Scientists have created artificial genetic material that can store information and evolve over generations in a similar way to DNA – a feat expected to drive research in medicine and biotechnology, and shed light on how molecules first replicated and assembled into life billions of years ago.

Ultimately, the creation of alternatives to DNA could enable scientists to make novel forms of life in the laboratory.

Researchers at the MRC Laboratory of Molecular Biology, in Cambridge, developed chemical procedures to turn DNA and RNA, the molecular blueprints for all known life, into six alternative genetic polymers called XNAs.

The process swaps the deoxyribose and ribose (the "d" and "r" in DNA and RNA) for other molecules. It was found the XNAs could form a double helix with DNA and were more stable than natural genetic material.

In the journal Science the researchers describe how they caused one of the XNAs to stick to a protein, an ability that might mean the polymers could be deployed as drugs working like antibodies.

Philipp Holliger, a senior author on the study, said the work proved that two hallmarks of life – heredity and evolution – were possible using alternatives to natural genetic material.

"There is nothing Goldilocks about DNA and RNA," Holliger told Science. "There is no overwhelming functional imperative for genetic systems or biology to be based on these two nucleic acids." ...
FULL STORY: https://www.theguardian.com/science/2012/apr/19/dna-alternative-xnas-science-genetics
 

EnolaGaia

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#18
Here are the bibliographic particulars and abstract of the cited research paper ...
Synthetic Genetic Polymers Capable of Heredity and Evolution

Vitor B. Pinheiro, Alexander I. Taylor, Christopher Cozens, Mikhail Abramov, Marleen Renders, Su Zhan3, John C. Chaput, Jesper Wengel, Sew-Yeu Peak-Chew, Stephen H. McLaughlin, Piet Herdewijn, Philipp Holliger

Science 20 Apr 2012: Vol. 336, Issue 6079, pp. 341-344
DOI: 10.1126/science.1217622

Abstract
Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage.
SOURCE: https://science.sciencemag.org/content/336/6079/341
 

EnolaGaia

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#19
But wait - there's more!! :boss:

Within the last year, computationally based studies have demonstrated there are potentially millions of polymer molecules which could serve the same purpose as terrestrial DNA / RNA.

One Among Millions: The Chemical Space of Nucleic Acid-Like Molecules
Henderson James Cleaves II*Christopher ButchPieter Buys BurgerJay GoodwinMarkus Meringer
Cite this: J. Chem. Inf. Model. 2019, 59, 10, 4266-4277
Publication Date:September 9, 2019
https://doi.org/10.1021/acs.jcim.9b00632
Abstract

Biology encodes hereditary information in DNA and RNA, which are finely tuned to their biological functions and modes of biological production. The central role of nucleic acids in biological information flow makes them key targets of pharmaceutical research. Indeed, other nucleic acid-like polymers can play similar roles to natural nucleic acids both in vivo and in vitro; yet despite remarkable advances over the last few decades, much remains unknown regarding which structures are compatible with molecular information storage. Chemical space describes the structures and properties of molecules that could exist within a given molecular formula or other classification system. Using structure generation methods, we explore nucleic acid analogues within the formula ranges BC3–7H5–15O2–4 and BC3–6H5–15N1–2O0–4, where B is a recognition element (e.g., a nucleobase). Other restrictions included two obligatory points of attachment for inclusion into a linear polymer and substructures predicting chemical stability. These sets contain 86,007 (CHO) and 75,309 (CHNO) compositionally isomeric structures, representing 706,568 CHO and 454,422 CHNO stereoisomers, that diversely and densely occupy this space. These libraries point toward there being large spaces of unexplored chemistry relevant to pharmacology and biochemistry and efforts to understand the origins of life.
SOURCE: https://pubs.acs.org/doi/full/10.1021/acs.jcim.9b00632

See Also:

https://www.extremetech.com/extreme/301888-researchers-find-more-than-1-million-alternatives-to-dna
https://bigthink.com/surprising-science/alternative-nucleic-acid
 
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#22
Study reveals life in the universe could be common, but not in our neighborhood

Source: phys.org
Date: 5 March, 2020

To help answer one of the great existential questions—how did life begin?—a new study combines biological and cosmological models. Professor Tomonori Totani from the Department of Astronomy looked at how life's building blocks could spontaneously form in the universe—a process known as abiogenesis.

If there's one thing in the universe that is certain, it's that life exists. It must have begun at some point in time, somewhere. But despite all we know from biology and physics, the exact details about how and when life began, and also whether it began elsewhere, are largely speculative. This enticing omission from our collective knowledge has set many curious scientists on a journey to uncover some new detail which might shed light on existence itself.

[...]

"However, there is more to the universe than the observable," said Totani. "In contemporary cosmology, it is agreed the universe underwent a period of rapid inflation producing a vast region of expansion beyond the horizon of what we can directly observe. Factoring this greater volume into models of abiogenesis hugely increases the chances of life occuring."

https://phys.org/news/2020-03-reveals-life-universe-common-neighborhood.amp
 

madmath

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#24
Or perhaps are we among the first planets with intelligent life?
Our civilization depends on a considerable number of relatively rare elements that are cooked up only in supernovae, basically every one above iron. So any species that achieves an equivalent level of intelligence plus tool-making abilities on planets created earlier than ours is going to have smaller amounts of these elements.
Also, we seem to be lucky in having a relatively big moon, which might help life form, though that's still debated.
And, depending on how we interpret fossils, it took hundreds of millions to billions of years for life to go multi-cellular. Perhaps that's a very rare circumstance across the universe. In our system Venus may have started out with life, and Mars, Europa, and Enceladus are all candidates for life but at best very simple forms.
So many factors go into bringing our species to this point that life may be quite common, but potentially interstellar traveling life may not have had time to develop elsewhere.
 

PeteByrdie

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#25
I've long since looked at it this way. Life appears to have emerged on Earth early in its history. Perhaps it even originated elsewhere. Either way, it remained unicellular for a very long time. The conditions of Earth and the Solar System seem, dabatebly, to be especially favourable to complex biology. Much talk is made of our tidal locking with the Moon making our planet relatively stable, protecting ecosystems from constant fluctuations that might inhibit evolution, for example. It's impossible to make a statistical analysis based on a single example, but we go on what we have. So, are there likely to be Earth like worlds outside the Solar System? Certainly. Are they likely to be equally favourable to complex biology? It doesn't seem so as far as we can see. But, obviously, in a vast universe, even a vast galaxy, there are likely to be some similarly favorable. So how likely is civilisation forming intelligence to evolve in such complex biology? We can't answer that, but brain power and social behaviour do seem to have independently increased in some taxa over time, suggesting to me that, while intelligence is not a goal of evolution (nothing is), given enough variety of complex life it will be likely to emerge.

My interpretation of all of this is that there is likely some complex biology in the universe, and a small amount is probably of civilisation level intelligence, and a tiny amount might even be space faring. But they will be rare enough to be spread across such huge distances, thousands of light years might separate them. Even if we detect them, even find a way to interact with them, I don't think we're looking at a Star Trek scenario, even in the best case. They'll be far enough away that their existence will be of only academic interest.

Now, it seems that our existence is reliant on a first generation of stars seeding the galaxy with certain elements. So, I think we're probably among the first civilisations in the Universe, and any others will be incredibly distant, and unlikely to be far beyond our levels of achievement.
 

INT21

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#26
Will the last people to leave Earth please turn off the lights.

But really, does it matter at all ?

It will be thousands of years before we actually HAVE to leave this planet.

And every one here will be very ancient history by then.
 

madmath

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#27
Of course it matters! To know that we are not alone, to talk with another, really alien species for their perspective and knowledge, to learn from them and teach them, and to discover new ways that life comes about and evolves.
Compare it to the ongoing discoveries of planets around other stars. Until the 1980s there were only the few we knew were around our own star; now we know that planetary formation is far more complex and surprising than most of our wildest imaginings.
 

James_H

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#28
Will the last people to leave Earth please turn off the lights.

But really, does it matter at all ?

It will be thousands of years before we actually HAVE to leave this planet.

And every one here will be very ancient history by then.
Maybe, maybe not. But I think it's quite likely that the distances between populated planets will be sufficient that communication of any kind will be impossible – islands of life doomed never to know of one another's existence.
 

INT21

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#29
James_H,

Indeed, islands of life that are forever moving further apart.

Madmath,

Sorry, but I don't think it will ever happen.

It's an interesting exercise to imagine others on other planets. But not entirely practical.

And if we can't communicate with any other beings, then they may as well not exist.

INT21.
 

PeteByrdie

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#30
Not exactly on the topic of the thread, but touching on many things discussed here. YouTube's weird algorithms have thrown me a video from early last year on Joe Scott's channel, which is an overview of the 'rare Earth' hypothesis, which I didn't know was a thing. So, I'll share it.

 
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