babble: No Moon, no life on Earth?

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Topic: No Moon, no life on Earth?

aRoused
rabble-rouser
Babbler # 1962

posted 24 March 2004 07:34 AM

New Scientist

quote:
Four billion years ago, when life began, the Moon orbited much closer to us than it does now, causing massive tides to ebb and flow every few hours. These tides caused dramatic fluctuations in salinity around coastlines which could have driven the evolution of early DNA-like biomolecules.
This hypothesis, which is the work of Richard Lathe, a molecular biologist at Pieta Research in Edinburgh, UK, also suggests that life could not have begun on Mars.

The hypothesis seems to be based on similarities to the process used to amplify DNA through PCR (where a change between two temperatures drives the process).

This in the context of the evolution/creation debate where the chemicals-to-life transition is often questioned on the basis of "life springing from unlife is impossible".

From: The King's Royal Burgh of Eoforwich | Registered: Dec 2001 | IP: Logged

Trinitty
rabble-rouser
Babbler # 826

posted 25 March 2004 10:12 PM

Very interesting.

I think it's a little premature for him to rule out life ever having started on Mars though. We sound silly in history books when we say such things.

From: Europa | Registered: Jun 2001 | IP: Logged

Ubu
rabble-rouser
Babbler # 4514

posted 26 March 2004 12:56 PM

If life has evolved on another planet, who is to say that it bears even the remotest resemblance to lifeforms on Earth, or even that it would be based on the same elements and molecules ?

From: position is relative | Registered: Oct 2003 | IP: Logged

HeywoodFloyd
token right-wing mascot
Babbler # 4226

posted 26 March 2004 01:24 PM

The theory of panspermia says that life on earth was origially seeded by lifeforms that arrived on meteorites. If that is true, then it is entirely reasonable to say that life on earth would be very similar to life not on earth.

From: Edmonton: This place sucks | Registered: Jun 2003 | IP: Logged

'lance
rabble-rouser
Babbler # 1064

posted 26 March 2004 02:00 PM

I don't think your second speculation necessarily follows from your first, Heywood. Microbial life forms could arrive here, and yet we could end up with utterly different forms developing to those on the original planet -- even assuming similar conditions.

Panspermia or no, life on earth could easily have turned out very differently to what it has, based only on some chance -- and very slight --variations here and there.

[ 26 March 2004: Message edited by: 'lance ]

From: that enchanted place on the top of the Forest | Registered: Jul 2001 | IP: Logged

Ubu
rabble-rouser
Babbler # 4514

posted 26 March 2004 02:06 PM

Given our current knowledge of only life on Earth, it is likely that life evolved right here. However, we do not know this. My point is that if life did evolve somewhere else, who is to say that cells were formed by phospholipid bilayers and that genes would be stored by DNA. Why couldn't some totally different type of life have evolved somewhere ? I'm certainly not discounting the possibility that there exist similarly-based lifeforms somewhere or that life might not have evolved on Earth. All I am really saying is the obvious. We don't know, so we shouldn't make assumptions.

From: position is relative | Registered: Oct 2003 | IP: Logged

HeywoodFloyd
token right-wing mascot
Babbler # 4226

posted 26 March 2004 02:07 PM

I agree. If the forms were microbial then they could evolve into completely different forms. What if they were of a higher order though? While their evolutionary path could alter upon exposure to earth's environment, it is reasonable to say that if they could survive arrival and exposure, then their new path would probably remain close to their original path.

From: Edmonton: This place sucks | Registered: Jun 2003 | IP: Logged

'lance
rabble-rouser
Babbler # 1064

posted 26 March 2004 02:11 PM

I have a hard time imagining any life form more complex than microbes either being transported by meteorites, or surviving entry into the earth's atmosphere -- or impact with the ground (or water) -- by that route.

From: that enchanted place on the top of the Forest | Registered: Jul 2001 | IP: Logged

Rufus Polson
rabble-rouser
Babbler # 3308

posted 27 March 2004 04:56 AM

DNA especially is, to my mind, just one very contingent possibility as storage molecules go. Bags of lipids might be pretty common, though--experiments have shown that they form spontaneously quite easily if the chemicals are around.

There's been a couple ideas about the moon being important--it's been suggested that the moon skimmed our atmosphere, stopping us from ending up like Venus Lite. Larry Niven has an odd little time travel story where a guy is in an abandoned alien installation on the moon, goes way back in time and accidentally drops a little alien artifact whose point disappears matter. It falls straight to the centre of the moon and starts eating, and when he goes forward in time again the moon looks like a beachball with the air let out and the earth has a huge greenhouse-effect atmosphere.

From: Caithnard College | Registered: Nov 2002 | IP: Logged

Agent 204
rabble-rouser
Babbler # 4668

posted 27 March 2004 09:03 AM

As far as panspermia goes, if we find life elsewhere we will have a very solid test of that theory- determine if these lifeforms have the same (or very similar) genetic code to us. Even supposing that DNA, and our twenty amino acids, provide the best basis for life (an assumption that is far from likely) there is nothing special about our particular code, except that once established there will be very strong selection against changes. So, if we find life elsewhere with the same code, we have to conclude that we share a common ancestor with it. The odds of the same code arising by chance are infinitesimal.

By the way Rufus, what's the name of that Niven story?

[ 27 March 2004: Message edited by: Mike Keenan ]

From: home of the Guess Who | Registered: Nov 2003 | IP: Logged

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