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Did newborn Earth harbour life? - Comments

Ygern's Avatar Comment 1 by Ygern

As a complete non-scientist, I have a question: would it have been possible for rudimentary life to have evolved, then be wiped out by the Late Heavy Bombardment and then re-emerge all over again?

Thu, 03 Jul 2008 06:48:00 UTC | #193321

Steve Zara's Avatar Comment 2 by Steve Zara

Comment #203582 by Ygern

Yes, that is possible. But the nature of life around now suggests something else happened. It looks like the ancestral forms of life from which we all evolved were thermophiles - able to live at pretty high temperatures. It is also possible they are related to the prokaryotes that now live quite a way down in the Earth's crust. Life could have appeared, and spread, but was then mostly wiped out, with only bacteria-like organisms deep in rocks surviving. Those then gave rise to everything else.

Thu, 03 Jul 2008 06:53:00 UTC | #193326

Ygern's Avatar Comment 3 by Ygern

Thanks for clearing that up for me Steve :-)

Thu, 03 Jul 2008 06:56:00 UTC | #193329

justinesaracen's Avatar Comment 4 by justinesaracen


It looks like the ancestral forms of life from which we all evolved were thermophiles - able to live at pretty high temperatures.


Ah, that could explain the origin of my hot flashes.

Thu, 03 Jul 2008 06:59:00 UTC | #193330

jenlaferriere's Avatar Comment 5 by jenlaferriere

That's a good question Ygern. I think that would really be quite interesting... I'm looking forward to hearing more about this as the details become available.

Think of what the Yough Earth Creationists would think of that.

Thu, 03 Jul 2008 07:02:00 UTC | #193334

Steve Zara's Avatar Comment 6 by Steve Zara

The physicist Paul Davies has been speculating about possible multiple origins of life. He asks an interesting question - if there were small organisms around with a completely different biochemistry, would we know they were there? We have barely begun to classify bacteria and archaea... there might still be a significant mass of life around from another origin.

Thu, 03 Jul 2008 07:06:00 UTC | #193337

Tack's Avatar Comment 7 by Tack

I understand that C-14 dating is only accurate within some tens of thousands of years.

Is it the case then that the method they used (examining the ratio of C-12 to C-13) can be used to gauge age in the order of billions of years?

Thu, 03 Jul 2008 07:24:00 UTC | #193344

Steve Zara's Avatar Comment 8 by Steve Zara

Comment #203605 by Tack

The ratio of C12 to C13 isn't being used here for dating. It is a possible signature of life. Biochemical processes tend to concentrate C12, so C13 (which is rare anyway) is even rarer in living organisms.

Thu, 03 Jul 2008 07:44:00 UTC | #193355

decius's Avatar Comment 9 by decius

Carbon is very common in the universe and even produced by stars. Its light isotopes could be concentrated by geological or volcanic processes not yet understood. The hypothesis in this article seems a bit far-fetched to me.

Thu, 03 Jul 2008 07:53:00 UTC | #193359

Steve Zara's Avatar Comment 10 by Steve Zara

Comment #203620 by decius

I agree. "An indication that it might be life" isn't really anything to get excited about.

Thu, 03 Jul 2008 07:58:00 UTC | #193361

DamnDirtyApe's Avatar Comment 11 by DamnDirtyApe

Didn't they find some life-relevant organic molecules in the sun recently?

Perhaps some of the key components of proteins were (probably still are!) constantly being forged, and the earth's proximity to the sun means it was constantly being seeded with them.

The sheer volume of material would certainly throw probability out the window. With those conditions it would only be a matter of time until exotic chemical reactions began and bam! Proteins, enzymes and bears, oh my!

Thu, 03 Jul 2008 08:13:00 UTC | #193367

ridelo's Avatar Comment 12 by ridelo

As I see what difficult circumstances life has been trough here on Earth, I can't imagine that we will not find it elsewhere. Even in our own solar system. When the first deciding data from Mars?

Thu, 03 Jul 2008 08:16:00 UTC | #193369

decius's Avatar Comment 13 by decius

Ridelo,

if you are referring to the Phoenix mission, its objective doesn't include looking for life, but to confirm the presence of water at the arctic region, to run a series of experiments on the soil, and to monitor the local weather.

The last mission which went to Mars with the official objective to look for signs of microbial life was Viking 2.

These things get distorted by the press in its quest for sensationalism.

Thu, 03 Jul 2008 08:24:00 UTC | #193375

ridelo's Avatar Comment 14 by ridelo

Decius,

Thanks for clearing me up. Nevertheless I'm a bit disappointed. Being there it would have been nice to look if anybody's at home. Even for a wee bit of DNA. Or something with the same function.

Thu, 03 Jul 2008 08:35:00 UTC | #193377

mordacious1's Avatar Comment 15 by mordacious1

A lot of speculation in this article, but that's OK. With all the speculation on early life that is being put out, some bright lad/lass will eventually put it all together and prove how life began. I think we are really moving forward on this and will someday have an accepted theory on the origin of life on Earth. We are close to closing that biggest of remaining gaps.

Thu, 03 Jul 2008 08:48:00 UTC | #193383

decius's Avatar Comment 16 by decius

In my opinion we are misdirecting a bit our efforts.
Granted that Mars is the natural backyard were to look in, there are far more interesting places in the solar system which we haven't properly investigated or not investigated at all.

Don't get me wrong, I would multiply our investments on Mars as well, but given the fact that budgets are tightening and huge wastes are perpetrated on the space station, I'd rather use those funds to explore Europa and Titan.

Titan for instance is an extremely dynamic world, with a mixture of dense atmosphere and low gravity.
Low-power drones or kites could stay aloft for years, just with the scarce solar energy available, and a large enough fleet could conduct hundreds of experiments continuously.

Suitable landing sites could be thus located for later missions capable of returning data of much greater interest than phoenix'.

Thu, 03 Jul 2008 08:52:00 UTC | #193384

mordacious1's Avatar Comment 17 by mordacious1

Decius

Agree with you on the large moons. I don't think I will see too much exploration there in my lifetime, which is too bad, for me.

Of course, we can have manned landings on Mars too, so that makes it more attractive to some.

Thu, 03 Jul 2008 09:12:00 UTC | #193389

Your_Noodly_Master's Avatar Comment 18 by Your_Noodly_Master

I've been wondering if it would have been possible for life to form in the protoplanetary disk and survive the formation of Earth. It seems like one of those hypotheses that is just crazy enough to be right. As I understand it, versions of the Miller experiment produce amino acids and other organic molecules at all kinds of starting conditions, and a protoplanetary disk would have a lot more surface area for reactions to take place than any planet.

Thu, 03 Jul 2008 09:21:00 UTC | #193391

AoClay's Avatar Comment 19 by AoClay

Europa and Titan, aside from Mars, are what I'd be fascinated with as well.

Thu, 03 Jul 2008 09:40:00 UTC | #193401

squinky's Avatar Comment 20 by squinky

I agree--this article is really evidence of very little. Remember the "fossilized bacteria" on the Martian meteorite ALH 84001 that made it into Science? There were probably hundreds of other non-life explanations but no, they jump straight through the line of hoops to conclude LIFE! Hype.

Steve Zara has done his reading on prebiotic life. Speaking as a chemist, the super-hard problem in prebiotic genesis is going from self-replicating molecules to DNA and RNA (now made by enzymes that presumably did not existent on pre-biotic Earth) to DNA and RNA being read by the ribosome to make proteins which then have function (like creating cell membranes, using chemical energy, etc--everything that defines life). DNA and RNA are essentially ticker tape with little to no function. To take this system and then advance to the simplest extremophile prokaryotic cell is a chasm so deep and wide that we don't even have a hypothesis yet of how it might have happened.

Thu, 03 Jul 2008 09:46:00 UTC | #193407

Steve Zara's Avatar Comment 21 by Steve Zara

Comment #203647 by decius

I generally agree with you. There are places in the solar system where we know that very interesting chemistry is taking place (Titan) and where we are pretty sure that liquid water is present (Europa, Enceladus).

Perhaps more research should be put into faster propulsion systems (ion drives, solar sails, even nuclear), so that we can explore such worlds on reasonable timescales.

Thu, 03 Jul 2008 09:46:00 UTC | #193408

Quetzalcoatl's Avatar Comment 22 by Quetzalcoatl

I'd be dubious about calling solar propulsion "faster"! Although I did read an article in New Scientist this week that a small solar-sail equipped spacecraft is due to be launched on 29/07/08.

Thu, 03 Jul 2008 09:53:00 UTC | #193411

Steve Zara's Avatar Comment 23 by Steve Zara

Comment #203670 by squinky

DNA and RNA are essentially ticker tape with little to no function. To take this system and then advance to the simplest extremophile prokaryotic cell is a chasm so deep and wide that we don't even have a hypothesis yet of how it might have happened.


I think you may be far too pessimistic. The relatively recent discovery that ice can concentrate nucleotides and assist polymerisation of RNA gives us least a vague idea of how the first replicators might have got started.

Thu, 03 Jul 2008 09:54:00 UTC | #193413

Steve Zara's Avatar Comment 24 by Steve Zara

Comment #203674 by Quetzalcoatl

I believe they can be very fast. The thing is that they don't run out of fuel. A solar sail craft could have covered the distance that the Voyager craft have travelled in a fraction of the time.

Just imagine the propulsion that would be present for a spacecraft that was flown close to the sun, and then opened a sail....

NASA's project is exciting!

Thu, 03 Jul 2008 09:58:00 UTC | #193415

AoClay's Avatar Comment 25 by AoClay

Steve,
I believe it was Carl Sagan who said he couldn't think of a better use for nukes than to propel spacecraft. We certainly need to make sure no problems would occur, but if not, man it would be the coolest way to get rid of them. I'd be very proud of that moment if it ever came.

Thu, 03 Jul 2008 10:01:00 UTC | #193417

decius's Avatar Comment 26 by decius

Steve,

I agree that propulsion to deep space needs a boost, both practically and figuratively.

However, the Helicon Double Layer Thruster could already be deployed after that it was successfully tested on orbiting satellites.
To give you an idea, a trip to Mars could last as little as three months at the engine's full potential.

If I am extrapolating correctly, one way to Jupiter's system would be reduced to approximately an year and a half.
Unless all other aspects of future missions are already planned, we are running the risk of having a functional propulsion system and nowhere to go.

Thu, 03 Jul 2008 11:20:00 UTC | #193450

Steve Zara's Avatar Comment 27 by Steve Zara

Comment #203716 by decius

However, the Helicon Double Layer Thruster could already be deployed after that it was successfully tested on orbiting satellites.


Thank you! Another day, another new thing I have learned from this site.

Thu, 03 Jul 2008 11:34:00 UTC | #193457

decius's Avatar Comment 28 by decius

Thank you too, Steve. I daily learn something from you.

Thu, 03 Jul 2008 11:43:00 UTC | #193462

Alovrin's Avatar Comment 29 by Alovrin

The comments here are more interesting than the article...
well to me.

Thu, 03 Jul 2008 12:03:00 UTC | #193466

robotaholic's Avatar Comment 30 by robotaholic

what if life actually initially evolved in the accretion disk which formed the solar system - just a stupid thought lol

Thu, 03 Jul 2008 14:30:00 UTC | #193522