I received this comment from an Intelligent Design creationist.
>> Shared pseudogenes in chimps and humans is not evidence
>> for evolution because humans design with common components.
There are many problems with the "shared components" argument of ID advocates.
First, some of those shared components are failed components. For example, pseudogenes in chimps and humans don’t work. That's why they are called "pseudogenes". Intelligent human designers don't reuse components that don't work in multiple designs. It would be irrational to do that.
Second, there are only shared components in places where evolution would predict that they would be shared.
Example: dolphins and porpoises share the same environment as sharks and are comparable in size. So why don't they share the component we call "gills"? Being able to breathe in the environment in which you live is surely an advantage over having to return to another environment frequently. Imagine humans being required to stick their heads in a bucket of water every hour or so.
In fact, if dolphins are unable to return to the surface, such as when they are caught in fish nets, they drown. Sharks don't drown.
So why didn't the "designer" reuse the gill "design"?
Evolution has an explanation for this. That explanation is that cetaceans (whales, porpoises and dolphins) evolved from land mammals that had lungs. Cetaceans developed adaptations for living in water - such as the movement of the "nose" to the top of the head and the ability to "hold their breath" for very long times. But to redevelop gills like those in a distant common ancestor would have required far too many specific mutations to expect that it could ever happen.
In other words, gills in cetaceans would falsify evolution.
But we don't see gills. You would presumably expect an "intelligent designer" to reuse that component.
Third, one of the reasons that human engineers reuse components is in order to save costs. If Chevrolet engineers reuse the same bolts as Cadillac engineers General Motors can purchase those bolts in larger quantities, thereby lowering the cost per bolt.
There are no demonstrated cost savings in using different DNA nucleotide sequences. So this would not be a factor.
Fourth, the ONLY other reason that human engineers reuse components is because of reliability. If you use a component over and over again, eventually it is "burnt in" and just about all design flaws have been removed. So if you reuse that component it will most likely work reliably.
But in fact, all engineers that I've known would prefer NOT to reuse components under these circumstances. If an engineer is instructed to reuse a component You generally will hear a very unenthusiastic comment like, "I suppose I can get that to work". In the electronics industry the switchover from vacuum tubes to transistors and other solid state components was delayed longer than it should have been simply because the engineering managers were reluctant to switch to new components when they had components that had been "burnt in" over many years.
If it was up to the engineers themselves, the switchover would have taken place much sooner.
An "intelligent designer" - especially if that "designer" is an omnipotent, omniscient God - would not be constrained by this factor either.
The bottom line - we would EXPECT to see very few reused components in nature if it is intelligently designed. The ones we see can all be explained by evolution and only by evolution.