Maybe DNA Was From Another Galaxy II
by: Dan Shanefield
After discussing my Meditation 626 with some other people, I now think that a few other ideas should be added to what I originally wrote. For one thing, our oceans contain huge amounts of methane, in the form of frozen methane hydrate on the sea bottoms. Some volcanoes like Mount Erebus emit nitric acid and ammonia gas, and possibly those were more abundant in our atmosphere a billion years ago, along with more carbon dioxide. If there was a lot of lightning, that combination might have generated amino acids and sugars, as did happen in the famous experiments done by Stanley Miller. (For further explanation, search for "abiogenesis" in wikipedia.org.)
However, a serious problem with the theory of spontaneous generation of life is that, even in arctic caves or on the ocean bottom, we don't see life's precursor materials, like early attempts by "Mother Nature" to make DNA, which were not quite successful. Or other life forms that were successful but are not quite the same as DNA. (From what I have read, all life on earth contains actual DNA, not just most of life. Even the lowliest bacterium or worm is made of DNA, amazingly similar to our own.) Why is there nothing here that is almost-DNA? Randomized self-assembly or such processes should have produced such material, maybe with a different twist or different chirality, etc.
My suggested answer is that possibly life started on another planet, in some other galaxy, where conditions were better for lightning-generated materials, self-assembling into DNA, and similar things. (Maybe there is less oxygen there.) The almost-DNA might still be there, both successful and unsuccessful.
The selection process that made only one type of DNA-based life come here to earth was that possibly an asteroid collision sent material to earth, maybe in a small chondrite meteorite, or maybe just as sand in a cold comet. Included was an asexual hard-shell seed or spore. Earth was warm and humid, and life prospered here.