No, it doesn't answer the "why" question at all.
Why does the vagus nerve swoop and droop as it does? The intelligent design would be to route the thing on the most direct route, not send it looping down into the chest from the brain to come back up to the throat.
Evolution answers the "why" of that easily enough. The vagus nerve loops down and about because that's what it does in fish, and our remote vertebrate ancestors were fish, and that's a holdover from that time.
Now, no intelligent designer is going to build all the workarounds we see in animals and ourselves, but blind evolution, working solely with what's available at the present moment, is going to wind up doing just that.
I don't think you comprehended the full meaning of my post. The intelligent designer would use mechanisms (evolutionary mechanisms) as I've said. This may include not changing things that don't require changing from species to species along the evolutionary pathway.
What you fail to realize is that you haven't answered
why the nerve swoops down. You've only shown
HOW it exists in all species of animals from fish to humans.
The only thing you've shown is that the shape of this nerve has not hindered reproductive success over the course of evolution. Why has this nerve not changed?
The simple answer: It had no bearing on reproductive success, therefore there was no reason for it to change. That doesn't answer why it exists in said form. To learn that, we must go back to the first ever species that this trait appears in and explain how it was reproductively beneficial for this swoop to be present.
Of course, since it did not change, it is in fact the OPPOSITE of evolution. It is the STAGNATION of a trait.
But let's say you actually explained the reason that the shape exists. All you would be doing is describing HOW that trait came into existence. There is no way you can explain WHY the first creature that had this trait came to exist, only HOW it came to exist.
Evolution can
only explain how a species came into existence. It cannot divine a purpose to that existence. ID tries to give a purpose to existence: God's will.
There may, in the end, not be a purpose. The answer to "why" may indeed be "No reason. It simply is what it is."
Evolution explains
how speciation occurs, but it can never explain
why it occurs. Individual traits are irrelevant to the discussion of these generalities.
Pure hypothetical reasoning ahead: Let's pretend that all of evolution exists solely to create an apex creature that is called "human". Perhaps the complexity of this apex creature required many steps along the path to not only create this creature, but also to give it a world where it can exist with a plethora of other creatures.
God may have "designed" evolution itself to reach this apex at some point along the line. It may have required many many steps along the way, which included the creation of the first creature to have the trait of a swooping vagus nerve. The existence of this trait was of absolute necessity for the first creature to have it, but became a vestigial trait for many creatures that evolved from it, including said apex creature.
But because the trait does nothing to hinder reproductive success of all the various species to have said trait, from the first to the apex species. Thus, there is no reason to "redesign" it in order to appease that apex creatures sensibilities regarding the designer. In essence, redesigning the trait takes unnecessary effort for the designer because said trait is of no hindrance whatsoever to the creation and sustenance of said apex species or any of the species that were the stepping stones to that apex species. If it was, then the trait would have changed. But since it wasn't, it remained the same. And in actuality, since the first creature with said trait absolutely needed it to survive, it was the correct design for the species that came afterward because they could not exist without the first species.
So the development of that shape was of absolute necessity to achieve the final, apex species design, even if it serves no directly observable purpose in that apex species because without the development of that trait in the original species that is a direct line to the apex species, said apex species would
never have come into existence.
So, although you have said that your belief is that the intelligent design would have been straight, that is false. The intelligent design was that which made it possible for the final species to come into existence. And that design is currently seen in all species of animals from fish to humans. Without that design, humans would not exist. The fact that it doesn't currently benefit humans is of no consequence because it had the ultimate benefit: It made it possible for them to come to be.
Anyone who believes in evolution can see that what I say above regarding the necessity of this trait existence in order for humans to exist
must be true. Without the first species to evolve this trait, which is a direct ancestor to humans, we could not exist in our current form (with this trait ourselves).
What is highly debatable is whether we are the apex species or that evolution exists solely so that we could come into existence. And these things must necessarily be true for Intelligent Design to be true. There must indeed be a purpose to evolution in order for design to be necessary.
That is what I meant when I said "why". The purpose of existence. Science is not interested in purpose, only mechanisms. Religion seeks to discover purpose.
Personally, as an atheist, I don't feel that a purpose exists. I allow for the hypothetical possibility that it could potentially exist, but I don't believe that there is a purpose. Nor do I believe in intelligent design.
But I can easily see how if there
is a purpose (or an answer to the "why" question if you will), evolution would be compatible with that purpose and not contradictory to it.
In the end, the why of existence can only be guessed at. It is my guess that there is no "why". For other people the guess is that there
is a why.
Disclaimer: This isn't an argument in
favor of intelligent design, I don't believe in ID. It is simply an illustration of how if it were to exist, it need not be considered incompatible with evolution.