There has been many examples of beneficial mutations - the peppered moth being the standard example of observed evolution on a quick scale.
With regards to beneficial mutation in humans, see the following link and note bullet points 3 and 4 in the below paragraph
http://www.talkorigins.org/indexcc/CB/CB101.html
2.Beneficial mutations are commonly observed. They are common enough to be problems in the cases of antibiotic resistance in disease-causing organisms and pesticide resistance in agricultural pests (e.g., Newcomb et al. 1997; these are not merely selection of pre-existing variation.) They can be repeatedly observed in laboratory populations (Wichman et al. 1999). Other examples include the following:
•Mutations have given bacteria the ability to degrade nylon (Prijambada et al. 1995).
•Plant breeders have used mutation breeding to induce mutations and select the beneficial ones (FAO/IAEA 1977).
•Certain mutations in humans confer resistance to AIDS (Dean et al. 1996; Sullivan et al. 2001) or to heart disease (Long 1994; Weisgraber et al. 1983).
•A mutation in humans makes bones strong (Boyden et al. 2002).
•Transposons are common, especially in plants, and help to provide beneficial diversity (Moffat 2000).
•In vitro mutation and selection can be used to evolve substantially improved function of RNA molecules, such as a ribozyme (Wright and Joyce 1997).
With regards to beneficial mutation in humans, see the following link and note bullet points 3 and 4 in the below paragraph
http://www.talkorigins.org/indexcc/CB/CB101.html
2.Beneficial mutations are commonly observed. They are common enough to be problems in the cases of antibiotic resistance in disease-causing organisms and pesticide resistance in agricultural pests (e.g., Newcomb et al. 1997; these are not merely selection of pre-existing variation.) They can be repeatedly observed in laboratory populations (Wichman et al. 1999). Other examples include the following:
•Mutations have given bacteria the ability to degrade nylon (Prijambada et al. 1995).
•Plant breeders have used mutation breeding to induce mutations and select the beneficial ones (FAO/IAEA 1977).
•Certain mutations in humans confer resistance to AIDS (Dean et al. 1996; Sullivan et al. 2001) or to heart disease (Long 1994; Weisgraber et al. 1983).
•A mutation in humans makes bones strong (Boyden et al. 2002).
•Transposons are common, especially in plants, and help to provide beneficial diversity (Moffat 2000).
•In vitro mutation and selection can be used to evolve substantially improved function of RNA molecules, such as a ribozyme (Wright and Joyce 1997).
