Life on Earth shockingly comes from out of this world

Jun 05, 2013 by Anne M Stark
Synthesis of prebiotic hydrocarbons in impacts of simple icy mixtures on early Earth.

(Phys.org) —Early Earth was not very hospitable when it came to jump starting life. In fact, new research shows that life on Earth may have come from out of this world.

Lawrence Livermore scientist Nir Goldman and University of Ontario Institute of Technology colleague Isaac Tamblyn (a former LLNL postdoc) found that icy comets that crashed into Earth millions of years ago could have produced life building , including the building blocks of proteins and nucleobases pairs of DNA and RNA.

Comets contain a variety of simple molecules, such as water, ammonia, methanol and carbon dioxide, and an with a planetary surface would provide an abundant supply of energy to drive chemical reactions.

"The flux of organic matter to Earth via comets and asteroids during periods of heavy bombardment may have been as high as 10 trillion kilograms per year, delivering up to several orders of magnitude greater mass of organics than what likely pre-existed on the planet," Goldman said.

Goldman's earlier work is based on computationally intensive models, which, in the past, could only capture 10-30 picoseconds of a event. However new simulations, developed on LLNL's supercomputers Rzcereal and Aztec, Goldman used much more computationally efficient models and was able to capture hundreds of picoseconds of the impacts—much closer to .

"As a result, we now observe very different and a wider array of hydrocarbon chemical products that, upon impact, could have created organic material that eventually led to life," Goldman said.

Comets can range in size from 1.6 kilometers up to 56 kilometers. Comets passing through the Earth's atmosphere are heated externally but remain cool internally. Upon impact with the , a shock wave is generated due to the sudden compression. can create sudden, intense pressures and temperatures, which could affect chemical reactions within a comet before it interacts with the ambient planetary environment. An oblique collision where an extraterrestrial icy body impacts a planetary atmosphere with a glancing blow could generate thermodynamic conditions conducive to organic synthesis. These processes could result in significant concentrations of organic species being delivered to Earth.

The team found that moderate shock pressures and temperatures (approximately 360,000 atmospheres of pressure and 4,600 degrees Fahrenheit) in a carbon-dioxide-rich ice mixture produced a number of nitrogen-containing heterocycles, which dissociate to form functionalized aromatic hydrocarbons upon expansion and cooling. These are thought to be prebiotic precursors to DNA and RNA base pairs.

In contrast, higher shock conditions (about 480,000 to 600,000 atmospheres of pressure and 6,200-8,180 degrees Fahrenheit) resulted in the synthesis of methane and formaldehyde, as well as some long-chain carbon molecules. These compounds are known to act as precursors to amino acids and complex organic synthesis. All shock compression simulations at these conditions have produced significant quantities of new, simple carbon-nitrogen bonded compounds upon expansion and cooling, which are known prebiotic precursors.

"Cometary impacts could result in the synthesis of prebiotic molecules without the need for other 'special' conditions, such as the presence of catalysts, UV radiation, or special pre-existing conditions on a planet," Goldman said. "This data is critical in understanding the role of impact events in the formation of life-building compounds both on and on other planets and in guiding future experimentation in these areas."

The research will appear on the cover of the June 20 issue of The Journal of Physical Chemistry A.

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cantdrive85
1.4 / 5 (28) Jun 05, 2013
Shockingly ironic, not from shock waves but instead electrically shocking.
Eikka
4.1 / 5 (14) Jun 05, 2013
I think there's a huge semantic leap going from organic chemicals that came from space and then formed life on earth, to saying that life itself came from space, because the latter implies that the organic molecules on these comets were already alive, or at least the products of life and not some other chemical process.
flashgordon
3.4 / 5 (10) Jun 05, 2013
I was going to say, "how does the dna and amino acids survive the impact?"

This idea is suggesting the impact energies give rise to the molecules of life and not lightning strikes as thought for decades now(and demonstrated back in the 1950s; i'm forgetting the name of the pioneer right now).
Eikka
2 / 5 (6) Jun 05, 2013
This idea is suggesting the impact energies give rise to the molecules of life and not lightning strikes as thought for decades


The main point is, that with the comet bombardment going on there's just more mass of organic molecules coming in faster than what could be created by lightning on earth itself.
ValeriaT
2.7 / 5 (19) Jun 05, 2013
What's so shocking about it? The panspermia hypothesis or E.T. initiated terraformation don't belong into mainstream hypothesis and this study is talking just about source of carbon, not about evolution of life outside of Earth. The whole article title is just a scientific journalism.
MaiioBihzon
2.4 / 5 (20) Jun 05, 2013
With all due respect, ValeriaT, I think the mainstream has shifted over the years toward acceptance of the possibility of life ~ or at least, life's basic ingredients ~ arriving on Earth from space.

http://web.mit.ed...323.html

http://www.pbs.or...ars.html

MIT and PBS are usually pretty close to the mainstream of science. Life might have come to Earth from Mars, or life's precursors may have been delivered once the planet's surface had cooled sufficiently for life to develop and survive here. Good news for people looking for life elsewhere in the Universe.
freethinking
1.3 / 5 (27) Jun 05, 2013
If you wait a really really really really really long time, something can come from nothing.
If you wait an additional really really really really really long time, something can become alive.
If you wait an additional really really really really really really really long time, that alive slim can become a human.

And they say I have faith.... :)
VENDItardE
1.8 / 5 (18) Jun 05, 2013
just more models with maybes not facts.
Jack_J_Smith
1.8 / 5 (10) Jun 05, 2013
the odds are against it, us and all life happening
josejgorbea
5 / 5 (3) Jun 05, 2013
I think its a great thing what these researchers have brought to the table, but it doesn't rule out Miller and Urey's reductive atmosphere hypothesis nor the deep-sea vents one either. What I'm really getting out of this is that probably the organic materials proposed by Miller and Urey came from comet impacts since, according to this article, these were scarce in early Earth's development. Still, its all a matter of speculation and we will almost certainly never find out the truth; I say we should just put these theories to the test on Mars and check if these scenarios are truly possible.
LarryD
3.7 / 5 (3) Jun 05, 2013
I view this article as just another idea supporting that a % of organic molecules came from space. The idea has been around too long for people to get excited about it and I don't think '...simulations...' are going to change the mood. Even if someone said "We know how Life was given a 'kick start'" I'm pretty sure the response from the general public would be along the lines of 'Oh, that's nice...' and it would only be important to the scientific section (and of course, the interested layman like me).
I think there are lots of reasons why the gp have become, shall we say, disinterested. Social and economic pressures give the gp little confidence in 'the experts' and unfortunately that, sometimes, includes the scientist. I think the gap is widening too. Apparently many people feel slave to science and that's a serious problem
I don't know the answer to this problem and I don't think articles like this one will help.
cantdrive85
1.3 / 5 (16) Jun 06, 2013
If meteors are debris from planetary catastrophe rather than failed planets or clumps or whatever, it would be expected that these materials would be present. How about suggesting that the genesis of the materials and the meteors they ride on were from planets. Not the other way around.
gwrede
3.2 / 5 (6) Jun 06, 2013
I think the article was ok. But the title definitely wasn't even close to the contents of the article. The inventor of that title for this article ought to be shot.

We all know that all material here originally came from space, including many molecules. This article says that a few more complex molecules came from space, and some were synthesized at impact. Now, that definitely doesn't qualify for "Life on Earth shockingly comes from out of this world", shocking or not. Some of these editors really are at the level of a 4-year old.
Why_
1.3 / 5 (12) Jun 06, 2013
I think that it is "funny" that the spontaneous generation" theory was debunked centuries ago, about the same time that the "cell theory" developed... (you know: All living organisms are composed of one or more cells. The cell is the basic unit of structure, function, and organization in all organisms. All cells come from preexisting, living cells.)
now, since we really can't explain how life began on earth to go along with Darwinian inspired thought, we are "switching" back to the "spontaneous generation" theory... it is laughable.

Silverhill
4.2 / 5 (5) Jun 06, 2013
@freethinking
If you wait an additional really really really really really really really long time, that alive slime can become a human.
And they say I have faith.... :)
Is 3E9 years not a really really really really really really really long time to you?

@Why_
I think that it is "funny" that the spontaneous generation" theory was debunked centuries ago
That kind of abiogenesis is not what is being discussed here. The old view had complete, fully modern organisms continually arising from inert materials.
DavidW
1 / 5 (12) Jun 06, 2013
If you wait a really really really really really long time, something can come from nothing.

And they say I have faith.... :)


It doesn't matter how long, if that's what the truth says, then it happens. Truth transcends time. The past doesn't exist, but the things that happened truthfully did happen and cannot be changed. Whatever does happen truthfully happens. These discoveries do not diminish the existence of a Creator, they support it.
tadchem
1 / 5 (3) Jun 06, 2013
Given the earth's atmosphere before the onset of 'life' contained methane, ammonia, carbon dioxide, and water with the occasional injection of volcanic gases, ash, and molten rock and metal, and with no evidence to contradict the high probability of electrical storms, the formation of large amounts of O3, N2, O2, H2, CO, NOx, and many organic compounds containing various proportions of many of these elements is inevitable.
Postulating that a major source of this material was meteoric seems insignificant, redundant, and almost irrelevant, as well as a contravention of the Principle of Parsimony.
It is a safe bet that none of the meteoric material was unique or alive.
Regardless of the source of the material, life on earth most likely developed on earth, and certainly has eveolved here.
If you have a smoking gun, it is pointless to debate where the ammunition was manufactured.
antialias_physorg
3.4 / 5 (10) Jun 06, 2013
It's interesting to play these probability games of where the first crucial parts of life originated/came from. It unfortunately doesn't get us closer to solving the question of where our type of life originated (whether it did originate here or was brought in from outside).

Singular events - assuming life only got started once - aren't open to statistical analysis.

However, when we look further afield (extrasolar planets, possible life elsewhere) things get more interesting. If space borne sources are a big contributor to fundamntal ingredients of life one could posit that this holds true elsewhere, as well - which would up the chances that life got started on other planets.

(But then again: since we don't know how likely it is that life gets started that doesn't really tell us how much 'up' from what initial probability we're talking about)

Still. An interesting piece in the puzzle.
barakn
3.7 / 5 (6) Jun 06, 2013
If meteors are debris from planetary catastrophe rather than failed planets or clumps or whatever, it would be expected that these materials would be present. How about suggesting that the genesis of the materials and the meteors they ride on were from planets. Not the other way around. -cantdrive85

Some are from planets, but most bear exotic minerals and isotope ratios that make it obvious they are not from planets. And moderate-sized impacts can explain the ones that do come from planets, there's no need to postulate planet destruction. Unless you're trying to fluff up some pet theory which doesn't have much evidence in its favor.
Torbjorn_Larsson_OM
1 / 5 (1) Jun 07, 2013
The estimate of ~ 10^13 kg/yr increases previous estimates of comet impact delivery of organics by 2 order of magnitude, and makes it a larger source than a reducing atmosphere under UV photolysis (~10^12 kg/yr; Despois, Cottin).

However, while hydrothermal vent delivery is now 5 oom less, ~ 10^8 kg/yr, it provides organics where it was most likely first used. (Homology between alkaline hydrothermal vent organics production under pH variation and metagenic chemoautrophs; Lane, Martin.)

No one argues against a post-differentiated Earth CHNOS organics delivery from comets and asteroids. It is a case which the recent GRAIL data on the Moon has tested a few times more, by having the same magnesium (volume; GRAIL) and water content (volume and isotopes; Apollo) on a heavily reheated Earth-Moon system (thin Moon crust; GRAIL).

But it seems only the P complementing to the full CHNOPS set has been an important impactor chemistry ingredient. [tbctd]
Torbjorn_Larsson_OM
3 / 5 (2) Jun 07, 2013
[ctd] But it seems only the P complementing to the full CHNOPS set has been an important impactor chemistry ingredient. It was just found in ~ 3.5 Ga bp sediments, and only there on early Earth, as iron meteorite product of phosphite, providing the oceans with reactive phosphorous.

@josejgorbea: Exactly, it is an offspring of "perhaps not a reducing so very organics productive early atmosphere". But we now know alkaline hydrothermal vents locally produce such reducing conditions.
Torbjorn_Larsson_OM
3 / 5 (2) Jun 07, 2013
@cantdrive, tadchem: It is not shocking that electric discharge (ED) is not important at all, as Miller once proposed. It has been known for a very long time that ED delivers many orders of magnitude less organics than comets, whether the early atmosphere was reducing (~ 10^9 kg/yr) or neutral (~ 10^7 kg/yr). [Despois & Cotton reviews this in their chapter in "Astrobiology".]

ct: Asteroids are _primordial_ debris, remains from the protoplanetary disk. But they have a complicated water chemistry producing organics as they heat from collisions or, if large enough, differentiation. It is the same processes, but different species of bodies.

@Eikka: An oversell, yes.

@Valeria: Transpermia from Mars is a serous contender in mainstream astrobiology. Review any textbook.

Personally, I don't think the numbers for Mars work. It was likelier with a local abiogenesis, given production, survival and delivery rates from a martian "tramway" of delivery vs times for local abiogenesis.
Torbjorn_Larsson_OM
3 / 5 (2) Jun 07, 2013
@freethinking, Jack_J_Smith, Why: No, life arose very quickly and so is a likely* process, as we can see in the fossil record. Now the Isua metamorphic BIFs, and by implication most or all BIFs, from ~ 3.8 Ga bp _of the first surviving sedimentary rocks_ are accepted as organically produced.

This is tested by astrobiologists having discovered how thermodynamics crystallizes a replicator RNA strand out of a random strand "gas" in ~ 30 000 years, forced by free energy of nucleotide activation.

Such nucleotides can be produced by products from cometary impacts, but more importantly alkaline hydrothermal vent chemistry is homologous with early autotroph metabolism. And now the missing piece, active phosphorous was found in barely younger sediments, in volumes to make the ocean concentration enough for activation.

We are now in the position that we don't know how life *could not* arise, given the observed conditions on early Earth and similar terrestrials.

@AAP: * [tbctd]
Torbjorn_Larsson_OM
3 / 5 (2) Jun 07, 2013
[ctd]

@AAP: * "Singular events - assuming life only got started once - aren't open to statistical analysis."

"Once" is a bad assumption, what we know is that one lineage survived or we wouldn't have universal common ancestry.

But worse the statistical claim is bad, basic statistics works that way, but statistical process parameters can be tested by single observations.

Admittedly you should use better estimates than that, but it is doable if you are forced. Production processes can be tested against single observations to be adjusted on-the-fly. Especially Poisson processes, the most generic, is putting a lot of statistical mass early on, so you don't need much to see if you are still within the process window.

Reversely, a quick Poisson process can be tested by an early observation, which we have here. Less than 1 Gy suffice with ~ 5 Gy total time, for a 3 sigma test. Isua BIFs clinches it.
Torbjorn_Larsson_OM
3 / 5 (2) Jun 07, 2013
"These discoveries do not diminish the existence of [magic], they support it."

Creationists shouldn't comment on science. It is hilarious, and it makes deconverts from religion, see Dawkins's Convert's Corner.

Obviously to all rational empiricists, the observation of a process that is without magic action tests the overall idea that there are no magic in existence. We know life arose without magic action because cellular biochemistry is at the root homologous to alkaline hydrothermal vent chemistry. Hence the evolutionary process did it, with chemistry that was at hand.

A creationists should be able to answer the question "what would make you give up your belief in magic?"

The observed fact that life *must* be a spontaneous product of a generic process should make many reject magic. The recent observed fact (Planck) that our universe is 0 energy and so *must* be a spontaneous product of inflation should make the rest reject magic.

Alas, creationists can't analyse their magic.
Anda
1 / 5 (3) Jun 08, 2013
I think there's a huge semantic leap going from organic chemicals that came from space and then formed life on earth, to saying that life itself came from space, because the latter implies that the organic molecules on these comets were already alive, or at least the products of life and not some other chemical process.


Just my thought reading the article. Sensationalist title.
That's the current theory, nothing new in it, just new and welcomed data.
beleg
1 / 5 (2) Jun 08, 2013
Earth is the garbage land fill of universe.
All life decomposes over long or short.

The two camps of science.
The romantics smell roses.
The cynics the stench.
Neinsense99
2.8 / 5 (9) Jun 08, 2013
I think its a great thing what these researchers have brought to the table, but it doesn't rule out Miller and Urey's reductive atmosphere hypothesis nor the deep-sea vents one either. What I'm really getting out of this is that probably the organic materials proposed by Miller and Urey came from comet impacts since, according to this article, these were scarce in early Earth's development. Still, its all a matter of speculation and we will almost certainly never find out the truth; I say we should just put these theories to the test on Mars and check if these scenarios are truly possible.

A negative on Mars would not necessarily mean a negative on Earth.
Mike_Massen
1 / 5 (2) Jun 09, 2013
Also for tadchem as an addenda,

Formamide forms easily and given some time and heat it forms a RNA/DNA amino acid Guanine...

Although its worth reading the whole article, the pertinent part is here:-
en.wikipedia.org/wiki/Formamide#Hypothetical_biochemistry

Its entirely possible a foundation block for several initial reactions producing DNA could have occurred before water was more prevalent,

Lower down re RNA is especially pertinent.
antialias_physorg
1 / 5 (3) Jun 09, 2013
[@]"Once" is a bad assumption, what we know is that one lineage survived or we wouldn't have universal common ancestry.
It is an assumption. Whether it is a 'bad' assumption remains to be seen. We just don't have any indication that life may have started several times - and hence no basis for making a statistical analysis. My comment merely reflects that there has to be spome bais from which one can make deductions/inferrences...and unknown multiple - or possibly singular events do not provide that.

Sometimes the "We don't know - we need more data" stance IS valid and the only one that can be sensibly taken .