Originally Posted by Jerthunter
Many scientists today believe that mitochondria and chloroplasts started off as a symbiotic relationship between types of cells. Although this theory did not get much support initally it has become widely accepted due to the overwhelming similarities between mitochondria and types of bacteria.
Also, concerning the 'most mutations are bad' statement, often times mutations do not get expressed, perhaps the mutation is not in a gene, are DNA has huge sections of unexpressed repeating sequences that can mutate without showing any side effects. So several mutations can build up over time without being seen until perhaps a promoter region gets moved via transposons or maybe by a virus inserting its own DNA.
Ok, point 1: How then do symbiotic relationships evolve? How did a eukaryotic organism survive without mitochondria, cell nucleus, cell membranes, etc.? Forget the complexity of man, look at the tiniest multi-cellular organism and the complexity of it's cells versus those of single celled organisms. There is a wide, and I would argue, impossbile gap between the two.
Point 2: If a mutation is not expressed it then would be of no benefit to the host, which wouldn't allow it a competitive edge, which then would not lead to it rearing more offspring and displacing the population with it's offspring. So, while on the surface this argument sounds good, it doesn't take into account the real issue of the numerical impossiblity unguided mutations would need to go through to form life from nothing; much less complex and diverse ecosystems.
