Panspermia, the Fundie Nightmare. All Sperm, All the Time!
Phil Plait has a good writeup on some recent space news. He writes that the Murchison meteorite:
…which fell on Australia in 1969, has been found to contain purines and pyrimidines, which are crucial to a large number of biological molecules like DNA, RNA, and ATP….
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Now the good part: scientists studying the Murchison meteorite have determined that the purines and pyrimidines — specifically, uracil and xanthine — have a non-terrestrial origin. In other words, the molecules in this meteorite, so crucial for life, were actually formed in outer space and fell to Earth.
Fundies like to yelp a lot that evolution doesn’t explain the origin of life. That’s right. We never claimed it did. The next time I hear that from a fundie, I’m going to reply “And Jesus didn’t invent popcorn!” That’s just as nonsensical of a statement.
The origin of life on Earth is an awfully good question, but we haven’t exactly figured out how it happened. Somehow, we had to go from the simple molecules that existed on the early Earth—such as carbon dioxide, methane, ammonia, etc.—and get to the more complex molecules that are part of living systems.
Some scientists think that environmental conditions on Earth were sufficient to turn the simple inorganic molecules into complex organic molecules. The most famous experiment to test this hypothesis was the Miller-Urey experiment. That experiment did change the inorganic starting material into organic compounds, including amino acids. You can read about the arguments for and against those results elsewhere, but similar experiments with different conditions have been run in the decades since. In many of these experiments, organic compounds were produced. These results indicate that the formation of organic molecules in the early days of Earth is a realistic and plausible hypothesis.
Another hypothesis is that the complex organic molecules formed elsewhere in the universe and rained down upon the Earth in a hail of meteors, asteroids, and comets. This idea is known as panspermia. The discovery of organic molecules in the Murchison meteorite shows that the panspermia hypothesis is also plausible.
It’s important to realize that this discovery does not prove panspermia. All it shows is that organic molecules can form elsewhere. So now we have two good hypotheses about the origin of life.
June 15th, 2008 at 2:15 am
I remember studying about this, personally I dont believe pansperimia is the answer, neithier is extraterresterial intervention. This theory states capsules of DNA were fired throughout the universe in the hope to spread life. But if this is the case how could you possible explain the formation of RNA based molecules, wouldnt this essentially be devolution
The miller urey experiment is the most plausailby although it has been critiscised for using too much H2 and the fact that it had unrealisitic assumptions of the conditions on eath back all those billions of years ago.
Some more evidence comes from tetrahymena thermophilia (i think that is how you spell it) This is an organism that has its own ribozyme suggesting that early RNA molecules could have self replicated.
June 15th, 2008 at 2:45 am
Sharaz:
This particular flavor of panspermia I’m talking about is just the organic precursors to DNA. That’s what was found in the meteorite. If that seeded the early Earth, all of the more complex molecules could have easily developed out of those.
The Miller-Urey experiment has been repeated with more realistic conditions, and organic compounds are still formed.
June 15th, 2008 at 9:05 am
What’s most amusing is that, even if the panspermia hypothesis turns out to be correct, it does virtually nothing to help the creations’ assertions. Whether the building blocks of life formed on Earth or elsewhere, they still formed in a natural environment, albeit not a terrestrial one. The question simply becomes, what is that extraterrestrial environment?
June 16th, 2008 at 2:21 pm
A veritable jism jamboree!