Complexity of gene codes (Introduction)

by dhw, Tuesday, August 24, 2010, 15:47 (5014 days ago) @ David Turell

David has given me a pretty comprehensive answer to the questions I asked in my post of 23 August at 19.02. Thank you. The gist seems to be that the Proterozoic era remains as much of a mystery as ever: Archaia may or may not have changed, we can't be sure of the significance of the Gabon fossils, the apparent stasis may not have been one, and there may even have been Cambrian-like explosions. It seems to me that our knowledge of life over this vast stretch of time is so scant that no matter what new discoveries are made concerning genome complexity, it is impossible to say with any degree of certainty whether all the mechanisms needed for evolution were already present in the earliest forms of life. (I also wonder how one can talk of an explosion when we know so little about the forms of life that existed beforehand!) Like Darwin himself, you can only rely on the thesis that the geological record is "imperfect". It seems entirely logical to me, though, that the early forms must have been adaptable, as you say, since life could not have survived otherwise in a rapidly changing environment, but adaptability is still a far cry from innovation, which is the problem I find most puzzling.-Interestingly, however, you say in relation to the Cambrian Explosion that the increased oxygen "allowed the genome to perform and create new organs and organisms", and it would be immensely helpful if you could elaborate on this, even if you think there must have been other factors too. No change of any kind happens in the abstract ... the genome can only "perform" within existing individual organisms. Darwin's gradual step-by-step process would scarcely have helped an individual organism to survive in an environment it could not cope with, and so either the changes had to be rapid, or they were not essential for survival. We're talking here about a wide variety of apparently new species, but new species can only evolve from old species, while new organs can only come into existence in organisms that didn't have them before. I'm not questioning that evolution happened, and of course natural selection played its part in preserving advantageous changes, but I'm trying to fill the gap between adaptation and innovation, following the same line of argument as before: that if organisms have not changed, their adaptability sheds no light on evolutionary diversification or advancement. That requires innovation. Why and how, then, do you think the rise in oxygen would have allowed (forced?) the genome of existing organisms to create NEW organs and NEW organisms?