Is it true that most mutations produce negative effects??...

[Anomalocaris]

This is what I've heard from someone who is a Creationist-that most mutations are harmful, and that's why he doesn't "buy" evolution. I have also read the argument that mutations don't result in different species-ie, a fly is still a fly, even with mutations.

Mutation is an pseudo-random event. Success in life depends on the organism's many characteristics - things that mutations can randomly change - remaining in relatively narrow range that would confer viability onto the organism. Take for example the level of activity of some endocrine glands - make the pituitory gland too active, and you grow into a clumsy giant unlikely to escape a charging predator. Make it too inactive and you can't reproduce. The lesson is if they fall outside that range, the organism either becomes sufficiently uncompetitive that it dies without producing an offspring, or produce offspring of diminished vitality. Either way the change is harmful from the point of view of evolution. Since the possible range of characteristics is large while the range of viable characteristics is small, random mutation indeed much more likely to produce an mutation that falls outside the viability range, and is therefore harmful, then one that falls within, and is therefore only potentially beneficial. For your creationist friend, so far so good. But from this point on he miss the point utterly and is full of shit.

The point is while mutation is random, the result of mutation is not. It doesn't matter if mutation that makes one stronger and faster is a thousand times less likely than one that make you blind or give you misshapen legs. In nature, the possessor of the the stronger or faster gene is more likely to survive, while the blind and genetically cripppled is sure to die. Bad mutations systematically die off. indifferent mutations systematically makes no difference, while good mutations systematically prosper at the expense of others. So all the mutations that makes one stronger or faster accummulate in the gene poor generation over generation, while those that blind you or make you a cripple is deleted from the gene pool almost as soon as it arise.

This is evolution. Evolution only requires mutation. It is not mutation. Evolution is the systematic sorting of the outcomes of mutation, discarding the bad, encouraging the good. Bible besotted creationists miss the point, one suspect willfully, lest they must grow up beyond 1000 BC.

What followed is another instance of creationists confidently missing the key point. When creationists say no mutation has been observed to change a fly to a non-fly, that is the sort of moronic truism akin to saying no single person has been observed to make a better spouse. A species is by definition a group of organisms capable of interbreeding and producing fertile offspring. A single mutation does not a group make. Creationists talk about species with supreme confidence in a way that betray the fact that they are utterly devoid of the most rudimentary grasp of what a species actually is.

When one look at a group of organisms [/i]capable of interbreeding and producing fertile offspring across multiple generations, one does indeed observe how of mutations through multiple generations can lead to the gradual formation of sub-populations of organism that are genetically more and more different from each other. Examples are literally everywhere, but the notable ones popularized by text books or every day examples range from Darwin's finches to the different breeds of dogs that strut around in a make-belief world of pet virtue. It is only a matter of time before sufficient genetic difference accummulate between subpopulations such that they are no longer capable of interbreeding between each other. When this happens two species have arisen out of what was formerly a single species. Gradual accummulation of beneficial mutations through generations in parts of a formerly genetically unified population until that part can no longer interbreed with the rest of the former population, and must now interbreed only amongst itself, this is how evolution create new species out of old. That creationists with their world view pivoting about infantile fantasy of of divine annointment of a single individual should fail to see the worthlessness of such notions in the real biological world is all together not unexpected, but it still betrays utter ignorance and intellectual dishonesty and lethargy.