It is, of course, relatively easy to induce mutation in a laboratory. Feed a pregnant momma rat enough chemicals or expose her to enough radiation, and you can create a rat-baby with two heads or with its intestines outside its body.
Mutation, however, is not a very useful technique for creating a faster or smarter rat. In fact, in thousands of years of observing people and animals, only a small handful of positive mutations have ever been observed. These are limited to examples such as the mosquitoes that have developed the ability to digest certain toxins through the production of specialized proteins.
This is not to say that given enough time and the right conditions, rats can't get faster or smarter. If slow, dumb rats get killed off faster than their buddies, then the genetic material that determines speed and intelligence will survive. This is the process of natural selection that Darwin observed. Birds with stronger beaks can live where there are harder seeds. Predators that have super-sensitive noses will be able to out-hunt those who don't. There is nothing in the idea of natural selection that contradicts the Bible. And it makes scientific sense. But natural selection doesn't require mutation. It just requires a certain degree of variation within the normative gene pool. If certain characteristics help creatures sustain larger populations, connect with fertile mates, or respond better to environmental changes, then their genetic profiles will gain dominance.
In fact, mutation is not a great way to improve a species. An overwhelming percentage of mutations are negative -- resulting in defective and/or stillborn offspring. One might even speculate that natural selection would select against susceptibility to mutation, since creatures that are inclined to mutation will see less of their offspring survive. Natural selection, in itself, would lead to the end of mutation-based evolution!
But mutations do occur, and not all of them are fatal. The Bible even makes reference to a few -- such as the giant of Gath who had six fingers and toes (II Samuel 21:20). The problem with evolution isn't the way it explains natural selection within a given species. The problem is the way the theory of evolution explains how all the different species we see today -- including man -- came into existence
