Trilobyte, I can't imagine what you're getting at with your incredulity regarding mutations adding up. Tossing out numbers of base pairs is meaningless.

An organism is born with a mutation. That mutation does not kill the individual or prevent it from breeding. That mutation is passed to the next generation. Another mutation occurs in the next generation...

What do you envision that prevents a mutation from being passed to the next generation? What do you envision that prevents mutations from accumulating?

When fascism comes to America, it will be wrapped in the flag and carrying the cross."
--S. Lewis