Meteorites Brought Ingredients of Life To Earth

Meshach writes "A new analysis of a meteorite found in Antarctica is leading scientists to think that life on Earth may have come from outer space. Chemical analysis of the meteorite shows it to be rich in ammonia and containing the element nitrogen. Nitrogen is found in the proteins and DNA that form the basis of life as we know it. The prevailing theory is that our planet may have been seeded by a comet or asteroid because the formative Earth might not have been able to provide the full inventory of simple molecules needed for the processes which led to primitive life."

Comments

Yes, but....

[gandhi_2]

..the meteorites were intelligently designed!

Boom.

Re:Yes, but....

[ColdWetDog]

Well, lets try to up the quality of the discussion and at least provide the abstract:

Abundant ammonia in primitive asteroids and the case for a possible exobiology

1. Sandra Pizzarelloa,1, 2. Lynda B. Williamsb, 3. Jennifer Lehmanc, 4. Gregory P. Hollanda, and 5. Jeffery L. Yargera

Abstract

Carbonaceous chondrites are asteroidal meteorites that contain abundant organic materials. Given that meteorites and comets have reached the Earth since it formed, it has been proposed that the exogenous influx from these bodies provided the organic inventories necessary for the emergence of life. The carbonaceous meteorites of the Renazzo-type family (CR) have recently revealed a composition that is particularly enriched in small soluble organic molecules, such as the amino acids glycine and alanine, which could support this possibility. We have now analyzed the insoluble and the largest organic component of the CR2 Grave Nunataks (GRA) 95229 meteorite and found it to be of more primitive composition than in other meteorites and to release abundant free ammonia upon hydrothermal treatment. The findings appear to trace CR2 meteorites’ origin to cosmochemical regimes where ammonia was pervasive, and we speculate that their delivery to the early Earth could have fostered prebiotic molecular evolution.

Without the full article it's hard to really follow why they think the earth needed excess organic chemicals, even specific amino acids, to be provided from meteorites. There is a large body of data that shows that amino acids, nucleic acids, lipids and a host of other moderately complex organic molecules could have been formed on earth at various times in it's development. As far as I can tell, there is nothing magical about the meteorite derived molecules and hence invoking panspermia (or more accurately, panorganicmoleculermia) is really unnecessary.

Anyone else out there with either access to PNAS or some better insight? So far it's a big meh.

Re:Yes, but....

[interactive_civilian]

I'm not an expert - so I may be wrong here.

As I understand it, life evolved QUICKLY on Earth. I mean, we went from a barren rock with magma flows and some water to teeming lakes of bacterium in the blink of an eye. (Relatively speaking). Only 500 million years after the heavy bombardment from meteors, and a mere 25 million years after the moon formed, Prokaryotes and Eukaryotes formed. As far as the universe goes, that's hardly any time at all.

  The best explaniation for this rapid growth is that life didn't actually have to start here, but came from meteorites.

  Again, I am not an expert, just an interested college student. Anyone with real knowledge, please correct me.

Your numbers seem off...

It was about 200-400 million years from the end of major bombardment to the first geological evidence of life on Earth. The moon formed before major bombardment ended. Approximate dates are 4.6Gya for Earth, 4.5Gya for the moon, 4.2Gya for the end of late heavy bombardment, and 3.8Gya for the first fossil evidence of life). The Wikipedia article on geologic time gives a pretty good overview. :)

As for the GPP, I agree. Every time they find something like this, there's always the "So Earth was seeded by these" speculation. It seems that such materials are rather common in our solar system, both here on Earth, on other planets, and on meteors and asteroids. If such organic molecules can form with relative ease in so many other places in the solar system, I see no reason why they couldn't have formed on Earth as well as it went through it's own geological evolution. Especially when geological processes for forming many complex organic chemicals abiotically have been documented. No doubt that stuff falling from the sky could contribute to organic materials on Earth, but I see no reason to believe that they are a major contribution.

As for TFS, I found this to be rather humorous:

Chemical analysis of the meteorite shows it to be rich in ammonia and containing the element nitrogen.

Well, I should hope so. I'd be very surprised and impressed if the meteorite were rich in ammonia but didn't contain nitrogen. :p

Re:Yes, but....

[presidenteloco]

"the answer for the simplest is God."

There. Fixed that for you.

Scientists do not need faith in their theories after they are proven. Scientific theories are verifiable according to a simply describable
rational process that anyone with skills can carry out without faith. Scientific theories are considered promising explanations of
parts or aspects of reality if
a) they are self-consistent,
b) they are logically consistent with other theories which co-define the same
terms (symbols for parts or aspects of reality),
c) they are structured as a mutually supporting set of statements which are particular assertions about the
presence and state of some things; assertions clearly enough stated in terms of other known/accepted concepts/terms/things that the assertions
could be falsified by comprehensible experiments carried out to measure the mentioned/described aspects of reality.
d) they have not been falsified yet, and
e) they are simpler (contain less information, in their so far unfalsified explanation of the same amount of phenomena) than competing theories.

"God did it" definitely fails c) in that the explanation does not explain any phenomena in terms of any other known (already explained)
phenomena/concepts/terms. Instead, it explains just about all phenomena in terms of a completely unknown, undescribed, and unexplained
posited entity, which might as well just be the concept "null" because it does not differ in description or properties from null except in the
completely circular and content-free sense in which it is defined as "the entity which is the cause of all these other phenomena".

God as prime cause stories also fail c) because in form they are generally rambling analogies or vague generalities which are not carefully
or coherently or specifically enough stated to be falsifiable assertions. Those specifics which are stated in the "God" stories have the
safety (from falsifiability) of being about alleged episodes lost in the mists of the past.

Most more detailed description of what this prime cause is like also fail b) in that the stories about God's appearances and works on aspects of reality are not consistent with other verifiable measures of those aspects of reality and also different versions of the God and God-cause stories are inconsistent with each other in many specifics.

Re:Yes, but....

[Ginger Unicorn]

However, science doesn't even ask the questions that religion answers - it doesn't ask "why".

Religion doesn't ask "why" either - it asks nothing. It proclaims a whole bunch of stuff, but enquiry is not part of faith. Faith by definition is unquestioning.

It seems to assume that the answer is "no reason, freak accidents",

It's good that you said "seems" there, as this is an absurd straw man that is merely what religious people project onto science as a reaction when science demonstrates the lack of necessity of their beliefs.

The term "freak accident" is loaded to imply that something, given everything we know about the physical universe, should not happen. This is a mischaracterisation of the scientific explanations for why humans exist. It is not series of unexplained events, at each step flying in the face of logic and understanding. It is a coherent thread constrained and predicted by a comprehensively tested body of rules, backed by 200 years of meticulous evidence collection. the only part of the process that is still a total mystery is the intial existence of the universe itself - the only reason for this mystery being that, as yet, it is impossible to collect any evidence about this event.

..irrational set of ethics that goes slightly beyond securing the most comfortable existence for themselves ... irrationally believe that there is a point in trying to preserve humanity

Those values aren't irrational. They are an inherent part of being a human. Believeing that they are not inherently human, and that they are infused from an external supernatural source is however, highly irrational. If god told you to kill your children, would you do it? It's moral because god told you to do it, right? Wrong, it isn't and you know it isn't because that urge to protect people you care about is part of the social emotions instilled in the human brain by millions of years of evolving in social groups. So when god told Abraham to kill his kid, he shouldn't have passed the test because he was prepared to do it - it should have been the other way round. God is basically grooming Abraham to be a mindless child-murderer, encouraging the "i was only following orders" excuse.

If I won't be alive to see my grandchildrens children, I really shouldn't give a fuck about them. Right?

If somehow you found out tomorrow that god doesn't exist, or that god sent down Jesus again and he told everyone to stop giving a fuck about there grandchildrens children, you'd still care about them wouldn't you? I have no religious beliefs, and happily accept that humans have no universal significance. Yet I'm not an amoral sociopath. This is not becuase science told me to care about people - i've been caring about people since I was first concious. It's because evolution has crafted a brain that values social bonding. My emotions and feelings, while being the product of cold emotionless processes are neverless real.

We're not special. We'll be wiped out eventually, and the universe will not notice.

You're right, the universe won't notice if all human life ceases to exists, provided the universe itself is in no way sentient, which there is not evidence to suggest it is.

Define "special".

if you define special as "having some significance" than of course we're special. We all have significance to ourselves and to everyone we know. If you define special as "being significant on a universal scale" then no, we are not special. You seem to be arbitrarily pinning your self-worth on something for which there is no rational objective evidence, and in terms of the biblical accounts, masses of counter evidence. This does not mean that you cannot have self-worth. You just need to realise that you are the person who is defining what gives you self worth. Not the bible or your church. Whether you realise this yet or not

And what seeded the comet or asteroid?

[thepainguy]

Seriously, I find ideas like this to be unsatisfying because they just pass the buck. Why is it any more likely that life would arise in a comet, asteroid, or other planet than it would be for life to arise on earth? Maybe if the earth was wiped clean by some cataclysm, but I don't know of anyone who's proposed that.

Re:And what seeded the comet or asteroid?

[Ouka]

The article didn't say life starting in space. One of the major problems with the leading hypothesis about how life began here on Earth is that many of the chemical elements required by said hypothesis were not present in sufficient quantities in early Earth. Or at least were not present based on what we think we know about the early composition of the planet. Chief among these problems is the absence of organic compounds in the rock matrix of the oldest known rocks.

Fast forward a few hundred million years and now these ancient-but-not-oldest rocks now have organic traces. What was different from when Earth cooled vs a few hundred million years later? Uncountable millions of comet and meteor strikes. Objects that have been shown to contain just the missing ingredients needed to complete the shopping list for the formation of Life.

Inert organic compounds have since been found throughout the known cosmos, from nebula containing ethanol to ammonia in asteroids. There are a multitude of hypothesis about why organic compounds form better in cosmic bodies instead of planets, from ionizing radiation in solar wind to the fact that planet formation is too hot an event for any traces of the compounds to remain after consolidation.

Not so sure

[jmv]

So the Earth's atmosphere contains about 4*10^19 kg of Nitrogen (surface of the earth * 100 kPa/g * 80%). That's a *lot* of mass. A 10 km asteroid (like the one that could have wiped the dinosaurs) is maybe 10^12 kg. So it would take more than 10 *millions* of those to provide the Earth with its current atmosphere -- assuming these asteroids were pure frozen nitrogen.

Another thing I don't quite understand is why the nitrogen would have to come from somewhere else. As far as I know, stars produce plenty of it (CNO cycle and all), so if we have carbon and Oxygen, why not nitrogen as well. Am I missing anything?

Fundamental Misconception of Occam's Razor

[Ginger Unicorn]

If you're going to cite Occam's Razor, you need to understand what it actually says. It's not just "the simplest solution is usually the correct one". There is one particular way that Occam's Razor can identify which arguments are objectively simpler than others. There is a very narrow range of arguments that can be compared with Occam's Razor. What it actually states is that if you have two comprehensive explanations for something that have the following form:

Explanation 1:

• parameter a
• parameter b
• parameter c

Explanation 2:

• parameter a
• parameter b
• parameter c
• parameter d

Since both explanations fully explain the same subject, Occam's Razor states that explanation 2 is less likely to be true as it is objectively more complex, since it is a superset of explanation 1, sharing parameters a,b and c, with parameter d simply introducing more opportunities for the explanation to be incorrect.

What you are trying to compare with Occam's Razor are apples and oranges.

Explanation 1:

• one of the many components of evolution a
• one of the many components of evolution b
• one of the many components of evolution c
• ...

Explanation 2:

• god did it.

Neither of these arguements is a superset of the other, so they can't be compared using Occam's Razor.

Although there are more parameters to the first explanation, there is no way to objectively measure or even define the "complexity" of each individual parameter to check that even if you add them all together, if they are more "complex" than explanation 2