As I pointed out in a previous post, this is not precisely correct. In plants, where I concede there is evidence for evolution, once genetic mapping of DNA was performed botonists found that they had misclassified many species. In some cases they not only had to move a classified species from one genus to another, they even had to move it from one family to another.
What is not compatible with intelligent design (but is compatible with stupid design) is the existence of shared errors in the dna of related species.
The counter example I give for this comes from software development. It is common practice to borrow extensively from previous designs and programs when building a new system. If there exists a section of code that is poorly written but "works", then time is not spent investigating it (since it works) but it is just copy/pasted and reused. Furthermore, even if there are errors in the copied code, if those exist in logic paths that are not exercised by the new programs then those errors remain. As an example, suppose that the errors occur in code used to print to some printers that are obsolete. Since those printers do not exist in the new environment, the fact that the code has errors in that area doesn't matter. Finally, since projects have contraints, minor errors that do occur are accepted if the value of copy/pasting previous code outways the impact of those minor errors.
It might (or might not) make sense for a designer to make use of common parts - it doesn't make much sense to me that both chimps and apes (to use my favorite example) should have been 'designed' to be susceptable to scurvy, by using the exact same scurvy mutation.
But in fact your example illustrates my point. If chimps and apes live in an environment where they have access to fruits or other vegetation that contains vitamin C, the fact that they are susceptible to scurvy is not that relevant.
A fundamental error, I think, made by those who reject intelligent design is that they assume something like: if speciation is directed by intelligent design, and intelligent design is performed by God, and God is perfect, why then we wouldn't see all this sloppy work. Ergo it was not directed by God, ergo there is no one to do intelligent design, therefore intelligent design is rejected. I suggest this:
In Western culture for all of recorded history there was a belief both in angels and "nature spirits". In Eastern culture for all of recorded history there was a belief in devas. (Devas might be considered to have the attributes of both angels and nature spirits.) The purpose of nature spirits was, in fact to guide and protect the growth and population of plants and animals.
One could hypothesize that for intelligent design, God simply subcontracted the work to angels (designers), who in turn had the nature spirits do the actual modifications (coders). And as someone who has extensive project experience and understanding of project constraints on the final result, one would absolutely expect errors, DNA coden reuse for new functionality, defects (mutations) that provide advantages but with damaging limitations, and so on.
Actually, evolutionary theory and intelligent design are not that far apart. The major difference is that evolutionary theory says "well, given enough time and geographical isolation it just happens" and intelligent design says "except what just happens is guided."
That not gonna go over well with the "God Doesn't Make Any Junk" bumpersticker crowd.
So our planet lucked out and got Clarence for its guide.
In most cases the errors found in the human genome are notlinked to nor are required in any way for the functionality of the "working" parts.
The major difference is that evolutionary theory says "well, given enough time and geographical isolation it just happens" and intelligent design says "except what just happens is guided."
This sounds more reasonable to me, and would be consistent with a common ancestor and shared errors observed. But it is no more falsifiable than the theory that angels guide the planets around the sun in addition to the natural gravitational forces.