The recurrent laryngeal nerve is a remarkable piece of unintelligent design. The nerve starts in the head, with the brain, and the end organ is the larynx, the voice box. But instead of going straight there it goes looping past the voice box. In the case of the giraffe, it goes down the full length of the giraffe's neck, loops down one of the main arteries in the chest and then comes straight back up again to the voice box, having gone within a couple of inches of the voice box on its way down. No intelligent designer would ever have done that.
Having never built a giraffe evolutionists do not actually know whether or not their recurrent laryngeal nerve is a shoddy design. In fact, it may well be that there are good reasons for the devious routing of the nerve.
But that is beside the point. Evolutionists forfeit nothing if the giraffe's recurrent laryngeal nerve has some reason to go down and back up its long neck. Regardless of the functions that are discovered, it obviously isn't efficient or elegant--it isn't an intelligent design.
Do you see the metaphysics that is deeply embedded in evolutionary thought? Regardless of how you feel about such designs, put yourself in the place of the evolutionist for a moment. Pretend that you genuinely believe that biology is an endless trail of hodge podge designs. That no creator or designer, otherwise capable of designing such incredible machines, would insert such clap traps into his designs. It would be like finding the steering wheel on backwards in a Ferrari. It makes no sense.
There are many scientific problems with evolution, but evolutionists are not in a position to contemplate any other possibility. Evolution--in one way or another--must be responsible for what we find in biology. Evolutionists have no other choice, regardless of the evidence. If you are convinced that "No intelligent designer would ever have done that" then guess what you will believe about evolution?
This argument from bad design may seem to rebuke the intelligent design theory, but it doesn't. ID is an appeal to the design in nature, not to the quality of those designs. The word "intelligent" is not a claim that the designs are smartly made--it is merely used to distinguish true design from apparent design.
We may not like a design, but that does not mean it was not designed. There may be evidence for evil or inefficiency, but that does not counter the evidence for design. Snake venom may be deadly, but it also is complex.
Judgments of the quality of a design can certainly be scientific. The efficiency, according to some metric, can be computed. The toxicity can be measured. But the use of such findings to determine whether a designer would have designed what we find in nature is necessarily not scientific. Such determinations require metaphysical assumptions.
The point here is not that evolution or ID are good or bad theories, or are true or false. The point is that, regardless of how one judges these ideas, evolution is a metaphysical theory whereas ID is an appeal to the empirical data and our scientific knowledge. This is why evolutionists are certain their theory is true. There is no way to conclude that evolution is as certain as gravity without non scientific premises at work.
Religion drives science and it matters.