Analysis of DNA supports the theory of evolution. The other point is that good science cleaves to the explanation with the least complexity that also covers the obsevred data. All the research of the last ten years on how complex systems evolve seem to support the notion that they are arrived at when a simple set of elements and a small set of rules arrives at a critically large number of transactions.
The explanations which includes all known physical phenomena and from those elements can provide a complete explanation of the phenomena is more elegant and therefore preferable, as science, than that explanation which requires the introduction of additional elements, especially elements which cannot be tested.
Intelligent design as a general concept is interesting and has been argued since the 1800s -- it is not a new concept. But because it is often associated with monotheism -- NOT a necessary concomitant of the ingredient of intelligence and design -- it probably gets shorter shrift than it could. But the biggest problem with it -- as evidenced in Dawkins' popular books -- is that it ain't needed.