Natural selection requires positive mutations (mutations that increase the probability of a creatures surviving and reproducing). The argument attempts to disprove natural selection and thus evolution by saying there are no positive mutations to act on. Of course, its wrong.

Mutations can be positive, negative (decreasing the probability of a creatures surviving and reproducing) or neutral (having no effect positive or negative). Over multiple generations positive mutations build up in a population while negative mutations due to them decreasing the probability of a creatures surviving and reproducing are ultimately weeded out of the population. This process is called natural selection^[1].

We know positive mutations occur. There are multiple examples of positive mutations.

• Bacteria can and have developed resistance to antibiotics. A mutation that gives bacteria resistance to antibiotics would increase its chances of survival and reproduction. Where other bacteria would be killed off by antibiotics it and its descendants of it would survive, live on and continue its infecting the host.^[2]
• Nylon is a synthetic polymer that does not exist in nature, it is solely made by humans^[3]. Because nylon is purely synthetic no organism was able to digest it and use it for food until a team at Department of Fermentation Technology at Osaka University discovered a strain of Flavobacterium living in ponds containing waste water from a factory that produced nylon, they discovered that the Flavobacterium had evolved the ability to use nylon-6 as food^[4]. It was found that this ability to digest nylon-6 evolved though gene duplication with a frame shift mutation^[5].
• Sense 1988 Richard Lenski has led a study into evolution known as the E. coli long-term evolution experiment. The study took 12 initially identical strains of E. coli and has monitored them for 22 years. Every 75 days (500 generations) a sample of each population would be taken and preserved then the scientists examine the relative fitness of the strains.
  In 2008 Lenski reported that one of the populations had developed the ability to metabolize citrate something that non of the populations before could do nor any strain of E. coli can do. In order for the population to evolve the ability to use citrate as food the population required multiple mutations all but that last neutral.^[6][7][8]
• Sickle-cell anemia or sickle-cell disease is a blood disorder where the red blood cells are a sickle shape rather than round like normal red blood cells^[9]. Sickle-cell anemia reduces average life span to 42 to 48 years^[10]. Sickle-cell anemia is a genetic disease caused by a mutation in the hemoglobin gene^[11].
  Sickle-cell anemia sounds like it would be bad (and it is) but sometimes evolution sucks. People with sickle-cell anemia are resistant to malaria^[12]. Malaria infects 350 to 500 million a year and over a million people die of it each year, mostly children^[13]. As a result in places with high rates of malaria people with sickle-cell anemia are actually more fit despite the lowered life span.
• Humans are the only animals that drink milk after we stop nursing and the only animals who drink the milk of other mammals.
  Humans started drinking animal milk after domestication of goats but theres a problem with drinking milk; lactose. Lactose is a sugar found in milk^[14]. Most mammals lose there ability to digest lactose but some humans are different. Most people start loosing there ability to digest lactose at age 2^[15] and genetic evidence has shown that five thousand years ago people did not have the mutations needed to be able to digest lactose into adulthood^[16].
  After the domestication of goats humans has access to the milk of the goats (later cows and water buffalo). Milk has needed nutrients and people who could drink milk would have access to those nutrients thus a mutation that gave people tolerance to lactose into adulthood would be positive and increase there fitness.
• HIV (human immunodeficiency virus) is an STD that causes AIDS (acquired immunodeficiency syndrome) a horrible fatal disease of the immune system.
  Not every one is equally susceptible to HIV. People who have a mutation in the CCR5-delta32 gene are resistant to HIV and people who inherit the mutation from both parents are virtually immune to HIV^[17].

Positive mutations are a fact. We know they happen.
© 2009 all rights reserved

Sources
1. Evolution part 6: Mutation, natural selection and genetic drift
2. The Rise of Antibiotic-Resistant Infections
3. the history of nylon
4. Utilization of a Cyclic Dieter and Linear Oligomers of
ƒÃ-Aminocaproic Acid by Achromobacter guttatus KI 72
5. Birth of a unique enzyme from an alternative reading frame of the preexisted, internally repetitious coding sequence.
6. Wikipedia - E. coli long-term evolution experiment
7. E. coli Long-term Experimental Evolution Project
8. New Scientist - Bacteria make major evolutionary shift in the lab
9. What is Sickle Cell Disease?
10. Mortality In Sickle Cell Disease -- Life Expectancy and Risk Factors for Early Death
11. How Does Sickle Cell Cause Disease?
12. Malaria and the Red Cell
13. CDC - Malaria
14. Wikipedia - Lactose
15. Lactose Intolerance
16. Understanding Evolution -Got lactase?
17. The Evolving Genetics of HIV Can genes stop HIV?

<-Part 7 | Part 9->