Duplication is just the beginning of a new use for the same sequence. Once a segment of DNA is duplicated, only one of the sequences is constrained to its original use while the other can mutate without any deleterious results until it hits upon a sequence that can may be useful.
Unless I am mistaken, [extra code is not always necessary to create a radically different creature.] is speculation.
Not speculation at all. Control sequences which modulate the expression of genes were identified long ago. The differential expression of genes accounts for a vast variation in phenotype. As it turns out, (and there was an article discussed on FR, recently), much of the difference between chimp and human brains can be attributed to the differential expression of the same genes.
Question. Does DNA by itself and in the presence of only unit bases in a constant pH and temperature replicate without intervention?
Nebullis, with all due regard, you are speculating. What would cause "the other" to mutate, how can we ensure there are no deleterious effects (mutations are generally extremely deleterious), what determines a favorable direction and what target is there for a sequence to hit upon? Do you see how these words "don't get us there" and are, at best, wishful thinking?
[The creation of a new creature is] not speculation at all. Control sequences which modulate the expression of genes were identified long ago. The differential expression of genes accounts for a vast variation in phenotype. As it turns out, (and there was an article discussed on FR, recently), much of the difference between chimp and human brains can be attributed to the differential expression of the same genes.
Well, what does this mean, "the differential expression of genes" and what is the control mechanism? You are again speculating. You surmise that differential gene expression results in differential phenotype, and while it would now seem logical, it is not established.
Quite correct - as far as it goes. However, what is important about gene expression is the mechanism for it. This is not a random mechanism, far from it. It is a very specific mechanism which tells each and every cell what genes to express and when. It is a mechanism which controls the actions of each and every cell throughout the organism's life. It is a mechanism which controls everything from the embryo's development to the time a person dies. Nothing random about it. In fact, it means that every part of an organism is tightly controlled by a set of instructions embeded in the genome. What this means is that a new gene is useless until it is coded into the organism's program to do something. This makes the arising of favorable new functions in a stochastic way totally impossible. It shows that evolution is totally impossible.