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On fire for Christ
SFN Regular

Norway
1268 Posts

Posted - 03/17/2007 :  11:21:55  Show Profile Send On fire for Christ a Private Message  Reply with Quote
When I see articles from various scientific sources such as the NASA website, or new scientist which speculate on the possibilty of life under the ice of europa, or mars or elsewhere in the solar system, I continue to hear the argument that if life can exist on Earth at the bottom of the ocean, or in lakes deep underneath glaciers and other extremely harsh conditions, then perhaps life could survive on these other worlds too.

Is it not logical though to assume that life on Earth arose from the most ideal conditions, then adapted to the harsher environments. If this is the case then it is very naive to propse that the actual genesis of life as we know it could occur in a dark, cold ocean.

Unless you subscribe to some kind of 'seeding' theory where life is carried from one world to another (which I see no need for) then we have to assume life originated on Earth from a cocktail of chemicals in some kind of random event, maybe this happened only once, maybe several times, or maybe it happens every day. Until we can identify this process I find it very shortsighted to imply the same process can happen on other bodies in the solar system with nowhere near the level of activity and environmental diversity we have here on Earth, merely because of the presence of water.

Discuss.

R.Wreck
SFN Regular

USA
1191 Posts

Posted - 03/17/2007 :  12:05:24   [Permalink]  Show Profile Send R.Wreck a Private Message  Reply with Quote
quote:
Originally posted by On fire for Christ

When I see articles from various scientific sources such as the NASA website, or new scientist which speculate on the possibilty of life under the ice of europa, or mars or elsewhere in the solar system, I continue to hear the argument that if life can exist on Earth at the bottom of the ocean, or in lakes deep underneath glaciers and other extremely harsh conditions, then perhaps life could survive on these other worlds too.

Is it not logical though to assume that life on Earth arose from the most ideal conditions, then adapted to the harsher environments. If this is the case then it is very naive to propse that the actual genesis of life as we know it could occur in a dark, cold ocean.





Welcome to SFN, On fire.

The problem is in the definitions words like "harsher" and "ideal". These are relative terms. Most, if not all, life on Earth today could not have survived the conditions most likely present when the first life arose on this planet. Take an Alaskan King Crab from the "harsh" arctic environment and put it in a comfy tropical lagoon and see how long it lasts. If life arises anywhere, it will necessarily be of a form which can survive the local conditions. So to "assume that life on Earth arose from the most ideal conditions" is a nonsensical statement. Ideal for any life form is that in which it can survive.

quote:
Unless you subscribe to some kind of 'seeding' theory where life is carried from one world to another (which I see no need for) then we have to assume life originated on Earth from a cocktail of chemicals in some kind of random event, maybe this happened only once, maybe several times, or maybe it happens every day. Until we can identify this process I find it very shortsighted to imply the same process can happen on other bodies in the solar system with nowhere near the level of activity and environmental diversity we have here on Earth, merely because of the presence of water.

Discuss.



Well, we currently have a certain level of environmental diversity and activiry, but it wasn't always so. When the first life arose on Earth, it was a far different world than you see today. In fact, the evolution of a biological system has changed the environment from severely oxygen deficient to today's level of ~ 20%. So the current environment on Earth really has nothing to do with the possibility of life forming elsewhere.

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Siberia
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Brazil
2322 Posts

Posted - 03/17/2007 :  13:56:35   [Permalink]  Show Profile  Visit Siberia's Homepage  Send Siberia an AOL message  Send Siberia a Yahoo! Message Send Siberia a Private Message  Reply with Quote
quote:
Originally posted by On fire for Christ

Until we can identify this process I find it very shortsighted to imply the same process can happen on other bodies in the solar system with nowhere near the level of activity and environmental diversity we have here on Earth, merely because of the presence of water.


But if it's a cocktail of chemicals, as we suspect it is, these chemicals can exist anywhere in the Universe (doesn't mean they are everywhere; but there's nothing stopping them from existing anywhere).

And if they do, given the right conditions (pressure, heat, etc) - if they do, there's nothing to stop them from creating life, just like when you heat water beyond a certain point, it boils. It's chemistry - not so simple like heating water, but still inevitable and straightforward.

And if one of the fundamental (to our understanding) ingredients for life is water, then the presence of water makes it more likely than the absence of it. Doesn't mean it WILL exist; but it's more probable that it does exist. We know life can survive harsh environments, so a given, potentially harsh environment is not an impediment for it, because we know there's life that can survive it.

The issue is the right conditions making life emerge from said chemicals, whichever those are.

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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 03/17/2007 :  15:20:12   [Permalink]  Show Profile Send HalfMooner a Private Message  Reply with Quote
Welcome to SFN, On fire for Christ!

Since we have not yet discovered life on any other astronomical body, and still only have the crudest of theories for abiogenesis on earth, it's both too easy and too difficult to speculate on how life might have arisen elsewhere.

Life on earth itself may have arisen from "seeding" (panspermia), but even if it did, that still brings up the question of how it might have first arisen elsewhere. (This is logically similar to the problem of explaining the existence of the universe by positing a Creator, as then you have the problem of what created the Creator.)

We're starting to get some very complex and logical biochemical hypotheses of abiogeneis, but none of these are complete nor accepted by science. Were I a young lad, this would be a great field to get into.


Biology is just physics that has begun to smell bad.” —HalfMooner
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Edited by - HalfMooner on 03/17/2007 15:22:17
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beskeptigal
SFN Die Hard

USA
3834 Posts

Posted - 03/17/2007 :  19:56:32   [Permalink]  Show Profile Send beskeptigal a Private Message  Reply with Quote
Panspermia doesn't fit the genetic evidence HM, unless it rarely arrives. Genetic evidence pretty much links us down to the earliest organisms except there is gene exchange among microbes that muddies the waters of the beginning just a bit. If there was new life arriving we would see very unique life forms with completely different DNA and we don't.
Edited by - beskeptigal on 03/17/2007 19:57:03
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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 03/17/2007 :  20:38:53   [Permalink]  Show Profile Send HalfMooner a Private Message  Reply with Quote
quote:
Originally posted by beskeptigal

Panspermia doesn't fit the genetic evidence HM, unless it rarely arrives. Genetic evidence pretty much links us down to the earliest organisms except there is gene exchange among microbes that muddies the waters of the beginning just a bit. If there was new life arriving we would see very unique life forms with completely different DNA and we don't.

Agreed, and I considered including that. It looks as though all life on earth came from a single microbial ancestor. And if this microbe came from another place than earth, it was either the only one to do so, or it ate any later arrivals. And unrelated alien life might very well use unknown genetic mechanisms analogous to but distinct from our DNA/RNA based ancestor.



Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
Edited by - HalfMooner on 03/17/2007 23:51:41
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Dave W.
Info Junkie

USA
26015 Posts

Posted - 03/17/2007 :  23:44:46   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message  Reply with Quote
Welcome back, On fire for Christ!
quote:
Originally posted by On fire for Christ

Unless you subscribe to some kind of 'seeding' theory where life is carried from one world to another (which I see no need for) then we have to assume life originated on Earth from a cocktail of chemicals in some kind of random event, maybe this happened only once, maybe several times, or maybe it happens every day. Until we can identify this process I find it very shortsighted to imply the same process can happen on other bodies in the solar system with nowhere near the level of activity and environmental diversity we have here on Earth, merely because of the presence of water.
As far as I'm aware, the current abiogenesis hypotheses are decidedly non-random, in that they all say that if a certain set of conditions come together, some sort of what we would consider "life" is inevitable. Because many of the molecules that seem necessary to life disolve in water, water is thought to be one of those conditions. In other words, places that don't have significant water are believed to have a much lower chance - perhaps zero - of "sprouting" life in any form.

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Dr. Mabuse
Septic Fiend

Sweden
9680 Posts

Posted - 03/18/2007 :  17:05:41   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message  Reply with Quote
There's a group of bacteria known as Archaeobacteria. They are not really true bacteria, but a very early branch-off from the part of the phylogenic tree that became cellular organisms.
Many Archaeobacteria are extremeophiles, which means that they thrive in what we consider hostile environments:
quote:
From Wikipedia:
They can survive and thrive at even relatively high temperatures, often above 100C, as found in geysers,black smokers,and oil wells. Others are found in very cold habitats or in highly-saline, acidic, or alkaline water.

These Archaeobactera are one of the earliest known forms of life.

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Dude
SFN Die Hard

USA
6891 Posts

Posted - 03/18/2007 :  21:19:04   [Permalink]  Show Profile Send Dude a Private Message  Reply with Quote
Some deep sea hydrothermal vents deliver water as hot as 400 degrees C, while the heat dissapates rapidly with distance from the vent, the areas surounding these vents teem with life (clams, shrimp, worms, and on down to bacteria).

So there are extremophile microbes and extremophile macroscopic species as well.

Some deep sea vents are literally teeming with life. I think I read one article where the estimated number of a single species of shrimp living around a vent was in the millions.

Not only can life survive in these harsh environments, it can thrive.


While you definitely cannot reach a definitive conclusion that life exists elsewhere in the universe, the observation of life thriving under extreme conditions does let you conclude that life could survive in places like the subsurface oceans of Europa.


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Hawks
SFN Regular

Canada
1383 Posts

Posted - 03/19/2007 :  02:08:58   [Permalink]  Show Profile  Visit Hawks's Homepage Send Hawks a Private Message  Reply with Quote
On fire for Christ, as you rightly point out, just because life (as we know it) can be sustained in an environment, it does not necessarily follow that life will actually be found there. Even "ideal" environments for life can be "dead" if the conditions are not right for life to either begin OR if there is no ability for life to move into it (call it panspermia between worlds or simply migration on the same world, if you wish). On Earth, of course, if you obliterate life from an environment (nuke it, for example) and wait for awhile, you will quite soon have life in it - not because of abiogenesis, but simply because already existing lifeforms moved there. Given that some micro-organisms can withstand high amount of radiation, high/non-existent pressure, cold and total-nutrient depletion for long amounts of time (basically, what is required to be transferred between worlds after an asteroid impact), we can at least reasonably speculate that life can be transferred between worlds as well.

But what about life arising without being seeded from somewhere else- i.e given no migration/panspermia, would we expect life to exist on Europa? This would obviously depend on the probability of life arising on said planet. Given that we don't know how life can arise in the first place, we obviously can't give a good answer.

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On fire for Christ
SFN Regular

Norway
1268 Posts

Posted - 07/16/2007 :  00:01:33   [Permalink]  Show Profile Send On fire for Christ a Private Message  Reply with Quote
But what about life arising without being seeded from somewhere else- i.e given no migration/panspermia, would we expect life to exist on Europa? This would obviously depend on the probability of life arising on said planet. Given that we don't know how life can arise in the first place, we obviously can't give a good answer.


I find it doubtful, and thank you Hawk for actually addressing the point I was trying to make.

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Dr. Mabuse
Septic Fiend

Sweden
9680 Posts

Posted - 07/16/2007 :  03:06:39   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message  Reply with Quote
Unfortunately, what is doubtful is in the mind of the beholder, and has little bearing on what might be real and not real.

Chemistry as we know it, says that it is probable.

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H. Humbert
SFN Die Hard

USA
4574 Posts

Posted - 07/16/2007 :  08:39:29   [Permalink]  Show Profile Send H. Humbert a Private Message  Reply with Quote
Originally posted by On fire for Christ
Until we can identify this process I find it very shortsighted to imply the same process can happen on other bodies in the solar system with nowhere near the level of activity and environmental diversity we have here on Earth, merely because of the presence of water.
Well, I don't think it's shortsighted at all. It is precisely because we don't know exactly how life began that looking for it elsewhere could yield enormous clues as to its ultimate origin. If we do find life on other warm, watery planet or moons, then that tells us a lot about how life begins. If we don't, then life on Earth may be more special than many scientists hope. Either way, I think the search for other lifeforms on distant worlds is absolutely worth it, since whatever answers we uncover will be illuminating.


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BigPapaSmurf
SFN Die Hard

3192 Posts

Posted - 07/16/2007 :  09:56:33   [Permalink]  Show Profile Send BigPapaSmurf a Private Message  Reply with Quote
Also I dont think it was pointed out that the life on Mars/Europa could have come from Earth or vice versa. It didnt nessisarily need to arise independently on those bodies, in fact I consider it far more likely that they would be seeded with life via ejecta rocks from earth.

Edit: Sorry Hawks beat me to this point...

"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History

"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini
Edited by - BigPapaSmurf on 07/16/2007 09:57:59
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On fire for Christ
SFN Regular

Norway
1268 Posts

Posted - 07/16/2007 :  10:13:16   [Permalink]  Show Profile Send On fire for Christ a Private Message  Reply with Quote
hawk said:
But what about life arising without being seeded from somewhere else


I found this doutbful

Dr Mabuse said:
Chemistry as we know it, says that it is probable.


Chemistry says life is probable on europa?

I find this also to be doubtful. Maybe you confused probable with possible.

If we do find life on other warm, watery planet or moons, then that tells us a lot about how life begins. If we don't, then life on Earth may be more special than many scientists hope. Either way, I think the search for other lifeforms on distant worlds is absolutely worth it, since whatever answers we uncover will be illuminating.


The trouble is Europa is not warm. It may have liquid water, however h2o alone will not spark a biogenesis. People are clutching at straws with europa. It's like a man dying in the desert looking for water, Europa is a mirage. I hope my weak metaphor really hammers my point home.

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H. Humbert
SFN Die Hard

USA
4574 Posts

Posted - 07/16/2007 :  10:23:37   [Permalink]  Show Profile Send H. Humbert a Private Message  Reply with Quote
Originally posted by On fire for Christ
The trouble is Europa is not warm.
Warm enough to have liquid water. That's within the temperature range for life to exist.
It may have liquid water, however h2o alone will not spark a biogenesis.
And no one is suggesting that "water alone" will spark biogenesis. However, we don't know exactly what conditions are necessary for biogenesis, so I'm not sure how you're arriving at the conclusion that Europe doesn't have them.
People are clutching at straws with europa. It's like a man dying in the desert looking for water, Europa is a mirage. I hope my weak metaphor really hammers my point home.
I understand your point, but not how you arrived at it. How are you so certain that life cannot have arisen independently on Europa? If there is geothermic activity under Europa's ice sheets, then they might not be so different from the hydrothermal vents here on Earth. And some scientists believe that these vents may have been the site for the first lifeforms on this planet. If that turns out to be the case, then it isn't at all improbable to think that life could initiate on Europe utilizing a similar mechanism. I haven't seen you offer sufficient evidence to dismiss this possibility.


"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes

"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman

"Face facts with dignity." --found inside a fortune cookie
Edited by - H. Humbert on 07/16/2007 10:25:40
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