Thursday, July 3, 2008 | Reason : In the News | print version

Did newborn Earth harbour life?

by New Scientist

Thanks to SPS for the link.

http://space.newscientist.com/article/dn14245-did-newborn-earth-harbour-life.html?DCMP=ILC-hmts&nsref=news3_head_dn14245

Did newborn Earth harbour life?

Life on Earth might have emerged about 750 million years earlier than previously thought, new research suggests.

Researchers have found unusually light isotopes of carbon, a common indicator of life, in the Earth's oldest mineral deposit, found in the Jack Hills in Western Australia. The carbon dates to more than 4.25 billion years ago, a time known as the Hadean period.

Life is largely considered to have emerged around 3.5 billion years ago, after a violent period known as the Late Heavy Bombardment, in which a large amount of space debris walloped and may have sterilised the Earth.

But the Jack Hills find suggests life might have existed well before that time, although researchers caution it is too early to draw a definite conclusion.

"We now have an indication that it might be life," says mineralogist Thorsten Geisler of the Institute for Mineralogy at the University of Münster in Germany.

Geisler and colleagues dated samples from the Jack Hills area by measuring the abundance of radioactive elements in zircon deposits. They then analysed the concentration of carbon-13 and carbon-12 found in small pieces of diamond and graphite trapped within the zircon.
Organic material

They found the ratio of carbon-12, a lighter isotope of carbon, to carbon-13 was unusually high. Light carbon suggests the presence of organic material.

But it is too early to say for certain whether the carbon might indicate life. "We can't say now that we have unambiguous evidence of life before the Late Heavy Bombardment," Geisler told New Scientist.

That's because certain non-biological chemical reactions can also create light carbon, although the ratio is so skewed towards the lighter isotope that these reactions can't easily account for it.

A reservoir of light carbon might also indicate that simple organic compounds might have existed on Earth, priming the environment for the later emergence of life.

"When I see that, that's really good news, because we need a reservoir of reduced carbon compound to set the stage for the origin of life," says Jeffrey Bada, a chemist at the Scripps Institution of Oceanography in La Jolla, California, US.

Journal reference: Nature (vol 454, p 92)

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1. Comment #203582 by Ygern on July 3, 2008 at 7:48 am

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?

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2. Comment #203587 by Steve Zara on July 3, 2008 at 7:53 am

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.

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3. Comment #203590 by Ygern on July 3, 2008 at 7:56 am

Thanks for clearing that up for me Steve :-)

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4. Comment #203591 by esuther on July 3, 2008 at 7:59 am

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.

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5. Comment #203595 by jenlaferriere on July 3, 2008 at 8:02 am

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.

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6. Comment #203598 by Steve Zara on July 3, 2008 at 8:06 am

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.

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7. Comment #203605 by Tack on July 3, 2008 at 8:24 am

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?

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8. Comment #203616 by Steve Zara on July 3, 2008 at 8:44 am

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.

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9. Comment #203620 by decius on July 3, 2008 at 8:53 am

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.

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10. Comment #203622 by Steve Zara on July 3, 2008 at 8:58 am

Comment #203620 by decius

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

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11. Comment #203629 by DamnDirtyApe on July 3, 2008 at 9:13 am

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!

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12. Comment #203631 by ridelo on July 3, 2008 at 9:16 am

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?

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13. Comment #203637 by decius on July 3, 2008 at 9:24 am

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.

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14. Comment #203639 by ridelo on July 3, 2008 at 9:35 am

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.

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15. Comment #203646 by mordacious1 on July 3, 2008 at 9:48 am

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.

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16. Comment #203647 by decius on July 3, 2008 at 9:52 am

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'.

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17. Comment #203652 by mordacious1 on July 3, 2008 at 10:12 am

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.

Other Comments by mordacious1

18. Comment #203654 by Your_Noodly_Master on July 3, 2008 at 10:21 am

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.

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19. Comment #203664 by AoClay on July 3, 2008 at 10:40 am

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

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20. Comment #203670 by squinky on July 3, 2008 at 10:46 am

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.

Other Comments by squinky

21. Comment #203671 by Steve Zara on July 3, 2008 at 10:46 am

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.

Other Comments by Steve Zara

22. Comment #203674 by Quetzalcoatl on July 3, 2008 at 10:53 am

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.

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23. Comment #203676 by Steve Zara on July 3, 2008 at 10:54 am

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.

Other Comments by Steve Zara

24. Comment #203679 by Steve Zara on July 3, 2008 at 10:58 am

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!

Other Comments by Steve Zara

25. Comment #203681 by AoClay on July 3, 2008 at 11:01 am

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.

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26. Comment #203716 by decius on July 3, 2008 at 12:20 pm

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.

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27. Comment #203724 by Steve Zara on July 3, 2008 at 12:34 pm

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.

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28. Comment #203729 by decius on July 3, 2008 at 12:43 pm

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

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29. Comment #203733 by alovrin on July 3, 2008 at 1:03 pm

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

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30. Comment #203791 by robotaholic on July 3, 2008 at 3:30 pm

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

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31. Comment #203806 by Rational_G on July 3, 2008 at 4:32 pm

Hmm... maybe panspermia is the answer?

Interesting that life emerges rather quickly in earth's history, whether it be 3.5 billion years ago or 750 million years earlier.

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32. Comment #203833 by asupcb on July 3, 2008 at 6:56 pm

Whenever we figure out how abiogenesis occurred it will probably involve a semi-accident with some guy saying, "that's interesting."

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33. Comment #203834 by steveroot on July 3, 2008 at 7:12 pm

26. Comment #203716 by decius on July 3, 2008 at 12:20 pm

To give you an idea, a trip to Mars could last as little as three months at the engine's full potential.

Does that include the (necessary!) deceleration at the end of the trip? If I remember my rusty physics, a spacecraft with an engine at constant thrust would have to turn around and brake for the last half of the trip. Is that close?
Ste5e

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34. Comment #203856 by decius on July 3, 2008 at 8:46 pm

steveroot,

that is generally correct for single engine crafts.
A combination of HDLT and rockets would considerably reduce deceleration time. Gravity and atmosphere drag are other options.

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35. Comment #203858 by steveroot on July 3, 2008 at 8:52 pm

34. Comment #203856 by decius on July 3, 2008 at 8:46 pm

that is generally correct for single engine crafts.
A combination of HDLT and rockets would considerably reduce deceleration time. Gravity and atmosphere drag are other options.

Well, what are we waiting for??
"I can gi' ye warrrp nine fer a while, Captain..."
:-)
Ste5e

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36. Comment #203861 by mordacious1 on July 3, 2008 at 9:08 pm

steveroot

Your avatar is going to give me nightmares.

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37. Comment #203882 by Laurie Fraser on July 3, 2008 at 10:11 pm

"Helicon Double Layer Thruster".....

decius, you just made that up, didn't you? ;)

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38. Comment #203921 by decius on July 4, 2008 at 12:19 am

decius, you just made that up, didn't you? ;)

Exactly, and to better fool you I added several wiki entries and a dozen dedicated web sites. :)

steveroot,

We are waiting that the idiots in Washington will recognise the futility of throwing trillions into conflicts and faith-based initiatives. They have also to accept that Europe is currently leading the way in propulsion, and stop funding less promising technologies.

Other Comments by decius

39. Comment #203926 by D'Arcy on July 4, 2008 at 12:44 am

Tack asks:

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?

The short answer is radiometric dating of rocks.
Wikipedia seems quite good on this:
http://en.wikipedia.org/wiki/Radiometrically_dated

The creationists have of course got their tame "scientists" to argue that God has made rocks that decay radioactively in line with a 6004 year old Earth. Pathetic stuff. Just Like God speeded up the light from anywhere outside of 6004 light years away in the unvierse to make it look 13.7 billion years old.

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40. Comment #203932 by hungarianelephant on July 4, 2008 at 1:03 am

I believe it was Carl Sagan who said he couldn't think of a better use for nukes than to propel spacecraft.

He did indeed.

Unfortunately, it's illegal to detonate nuclear devices in space. And we don't want Bush in front of a tribunal of international law, now do we?

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41. Comment #204134 by steveroot on July 4, 2008 at 8:14 am

36. Comment #203861 by mordacious1 on July 3, 2008 at 9:08 pm
steveroot

Your avatar is going to give me nightmares.

What? You don't like the New Testament Convenient Version?
http://www.landoverbaptist.org/2008/july/dobson.html
:-)
Ste5e

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42. Comment #204138 by Vaal on July 4, 2008 at 8:20 am

40. Comment #203932 by hungarianelephant

Unfortunately, it's illegal to detonate nuclear devices in space

Why? Space is saturated with radiation from the sun, not to mention the radiation from Jupiter is lethal all the way out to most of its major moons.

The sooner nuclear propulsion is adopted the quicker we shall be able to properly explore and start making the most of the resources of the solar system, instead of depending on the finite Earth.

Other Comments by Vaal

43. Comment #204146 by hungarianelephant on July 4, 2008 at 8:33 am

Vaal - Good question.

It's contrary to the 1963 Limited Test Ban Treaty. The treaty was negotiated in the aftermath of the Cuban Missile Crisis. Nerves were shot and no one liked the idea of big explosions above ground. Hence all detonations other than underground ones were banned. This specifically included detonations outside the atmosphere.

At the time, it was probably a sensible way of trying to avoid mass slaughter. Perhaps the time has come to amend it ... though you can imagine the hysteria that would be whipped up if any politician suggested it.

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44. Comment #204169 by ridelo on July 4, 2008 at 9:15 am

My guess is that if we find life elsewhere it will also be RNA-based. I suppose that when replicating molecules started competing in the primeval soup RNA came out as the best and out competed the rest. In similar surroundings (like in Europa's ocean) RNA will also be the winner. But it's only a guess. Maybe I overlooked essential evidence.
And maybe it started elsewhere and spread trough a sort of 'pan-RNA-ia'. Have there ever been found shreds of RNA or DNA in meteorites?

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45. Comment #204190 by Vaal on July 4, 2008 at 10:59 am

43. Comment #204146 by hungarianelephant

It's contrary to the 1963 Limited Test Ban Treaty

Yep, I remember the fuss when the Galileo probe was launched with plutonium on board. They may have a point as far as launching inside the atmosphere, but I think there is a strong case for nuclear powered spacecraft which are placed permanently out of the atmosphere, perhaps based at a lagrange point.

It will drastically reduce costs of interplanetary exploration and, best for the crews, actually reduce exposure to the solar wind, as the travel time will be drastically reduced.

Absolutely that treaty should be revised. It is ridiculous. Time some politicians actually grew some balls!

Other Comments by Vaal

46. Comment #204194 by decius on July 4, 2008 at 11:13 am

There is an intrinsic risk in putting into orbit large amounts of fissile material, and the Nuclear Pulse Propulsion is very costly. Not really the way to go at the moment, considered the better alternatives.
It was a great idea back in the 50s-60s, obsolete now.

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