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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."
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.
Faster! Faster! Faster would be better!
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
"Empathise with stupidity, and you're halfway to thinking like an idiot." - Iain M. Banks
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.
"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.
Where are we going and why are we in a handbasket?