On the origin of life
In Meditations 626 and 627, Dan Shanefield raised the possibility that DNA may have originally arrived on Earth from somewhere else in the universe. I have generally not been a supporter of the the idea that life came from outer space; it just seems to add unnecessary complications. However, each of two recent consecutive issues of the New Scientist has introduced a new hypothesis related to possible extraterrestrial origins of life.
- In the August 18-24 issue, it was noted that a computer simulation at the Max Planck Institute for Extraterrestrial Physics had shown that inorganic dust immersed in an ionized gas (conditions in deep space) can organize itself into spiral structures that behave in many ways like living organisms; reproducing and passing information to one another. These dust spirals sometimes develop as double helices, just like DNA.
- In the August 25-31 issue, Chandra Wickramasinghe of Cardiff University has suggested that evidence of clay in comets indicates liquid water was also once present in comets. Clay needs water to form, so at one time, comets must have had warm and wet interiors. Further, clay is a possible catalyst for the conversion of simple organic molecules into complex biopolymers. And given the number of comets, there were more opportunities for life to originate on one of them than under similar conditions on Earth.
There are a lot of gaps between either of these hypotheses and the first cellular life form to appear on Earth. These are just two more to add to the hundreds of previous hypotheses, both terrestrial and extraterrestrial, that have already been developed. And as yet none of them have been shown to produce life, just molecules that might have been precursors to life.
There is still a lot to be learned; the answers are not yet available. I expect that eventually science will discover a process that will result in creating life. Perhaps it will identify several, if not many such processes. It may still not be possible to say with certainty which, if any, of these specific processes actually led to our common single-celled ancestor.
It is claimed by those who reject natural origins of life that such origins are so unlikely that a deity must have been responsible. The counter-argument has been that with the expected large number of Earth-type planets in the Universe, the unlikelihood on a single planet turns into near certainty with millions or billions of planets.
If we further consider that there may be multiple processes, each of which could possibly result in life, the probability of a natural origin is further increased. The intervention of a deity is not required.
- Deep-space dust spirals into 'life" New Scientist, August 18-24 2007 p.15
- Did a warm, wet comet kick-start life on Earth? New Scientist, August 25-31 2007 p.14
- However, not as big as the huge gap between the hypothesis that "God did it" and the first cellular life form to appear on Earth.