(June 18, 2013 at 1:05 am)Chuck Wrote:(June 16, 2013 at 1:30 pm)max-greece Wrote: Do we need an external energy source? It seems that a young earth would be an extremely energetic one. Even now under the deeps of the ocean there is constant seismic and volcanic upheaval.
Once the seas had formed it would probably be only a matter of time before the right chemical reaction took place to produce an RNA chain capable of replicating.
As the earth seems to have been about 500 million years old before life started that, I would guess, is all the time needed.
An equally interesting question, of course, is why, about 3.5 billion years later multi-cellular life started in the Cambrian explosion.
Actually that is 2 questions - why did it take 3.5 billion years to happen and what caused it?
1. There are hints that life existed on earth 4.2 billion years ago. So life may have taken less than 300 million years to arise from the accretion of the earth. Since the earth during her first hundred million years and more must have been truly hellish place, and utterly inhospitable to any life, life may have in fact taken far less the 300 million years to arise starting from the first moment when earth's environment first became suitable for giving rise to life.
2. The notion that multicellular life arose with Cambrian explosion is wrong. As matter of fact, there was a diverse pre-Cambrian multicellular fauna called the ediacrean fauna that left a rich fossil legacy. But Before ediacrean fauna there were another 300 million years of clear trace fossil records of complex multicelluar animal life such as worm burrows, crawl marks, etc. More ambigious trace fossils suggests some mobile complex multicellular life may have existed over a billion years ago. All Cambrian explosion really represented was a major change in sea water chemistry that enabled the development and preservation of mineralized body parts, hence extensive preservation of actual body fossils. The fact the Arthropods at the very beginning of Cambrian explosion already possessed the full suite of highly evolved, specialized adaptive features that distinguish different branches of anthropod family tree down the ages to today, shows that not only did some form of complex animals exist before the Cambrian explosion, but specific forms of highly evolved complex animal life clearly distinguishable as belonging to still extent phyla, and directly ancesteral to existing classes and orders of those phyla, must have existed since before the Cambrian "explosion".
Great stuff there Chuck although even if multi-cellular life is actually a billion years old that still leaves a 3.2 billion year gap if life started even further back.
Do you have any source material for the pre-cambrian? Everything I have seen starts from the Cambrian explosion and only makes reference to fractal life forms before that which appear to have simply died out.
