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

Vertigo

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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.
 

paranoid marvin

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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.
 

K. Riehl

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"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."

 

RJM Corbet

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"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?


"… 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

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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.
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.
 

Vertigo

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Did DNA come before or after the LUCA?


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

RJM Corbet

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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?


"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)"
 

Matteo

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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.
The first episode is about how life needed volcanoes to evolve:
Thanks! Had missed this. Will be tuning in.
 

BigBadBob141

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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!
 

Oligonicella

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We have one and only one instance of life we're aware of. Which also means, statistically speaking, life in the universe is a certainty.

Any guess as to others or not is just a guess. The Drake equation is worthless, as if you play with the impossible to know variables you can get 0 (obviously false) or a large number.

It's not even worth contemplating with trillions of galaxies containing trillions of stars.
 

Parson

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Clearly the answer is somewhere between 1 (although sometimes I doubt that) and that very large number. even if there were only one per galaxy.
 

paranoid marvin

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The fact that life is possible within an (almost) infinite universe, over an (almost) infinite span of time, means that there are (or have been, or will be) an (almost) infinite number of planets that hold life.

And as the bar for the human definition of 'intelligence' is so low, there will undoubtedly be (or have been, or will be) an (almost) infinite number of planets that hold intelligent life.
 

RJM Corbet

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The fact that life is possible within an (almost) infinite universe, over an (almost) infinite span of time, means that there are (or have been, or will be) an (almost) infinite number of planets that hold life.

And as the bar for the human definition of 'intelligence' is so low, there will undoubtedly be (or have been, or will be) an (almost) infinite number of planets that hold intelligent life.
But this is an assumption?

The science is that allowing (obviously) for abiogenesis and the consequent spread of bacterial life, the jump from bacteria to eukaryote by endosymbiosis between bacteria and archaea is hugely unlikely.

It is regarded as an absolutely unique and one-time-only never repeated event upon the planet earth. Bacteria and archaea swarm the earth in billions of trillions -- so why isn't it happening all the time?

Although the abiogenesis of prokaryote bacterial life is possible elsewhere in the universe, the jump to eukaryote> intelligent life is not at all likely?

In the end, if we are going to use terms like infinite and almost infinite -- there are going to be an infinite, or almost infinite, number or worlds that contain an exact, or almost exact replica of me? But is there any justification to assume just because 'me' happened once here -- that I am bound to happen elsewhere too?
 
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Ursa major

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Bacteria and archaea swarm the earth in billions of trillions -- so why isn't it happening all the time?
Perhaps because the conditions are now different.

Apart from anything else, the organisms that would be the result of the mutations (and other mechanisms that might be involved) amongst those current-day bacteria and archaea would be entering a world full of existing organisms that are already well adapted to their environments (as opposed to ones that are not so well-adapted).
 

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