Why do they, in a best-case scenario, spend several hours reading, evaluating, and constructively commenting on a manuscript from a group of authors they might not even know? The reasons are many, oft repeated, and about as varied as the comments that reviewers provide on a single paper, on a scale as broad as the human nature from which they derive. Among the more frequently cited motivations are civic duty (good scientific citizenship), loyalty to a particular journal, probable need to read and critique the paper anyway, once it's published, and a desire to control and influence the presentation of science, for noble or ignoble reasons. Dear ALL!! Please find attaced file!!