Intelligent design is less robust and adaptable than evolution by mutation and natural selection.
That said, I'd like to start accelerated human evolution by upregulating PEPCK-C. If you're curious what this does to a mammal, you should watch this video (and turn the volume down so you don't have to hear Creed):
These mice eat 60% more than the average mouse, but never get fat, are fucking ripped, have triple the equivalent endurance of an Olympic athlete, live up to five times as long, stay fertile throughout their lifespan, and don't suffer any of the traditional effects of a high-fat, high-cholesterol diet.
Why don't we have this mutation already? Likely, because of the 60% larger diet thing; human evolution has been a process driven primarily by starvation, it seems.