Effect of Varying Doses of Caffeine on Life Span of Drosophila Melanogaster

To the Editor: Despite a considerable interest in the effect caffeine has on metazoan life span, the extent, as well as the direction, of this effect is still unclear. One of the most extensively used metazoan models in longevity studies is the fruit fly Drosophila melanogaster (1). There are a number of studies on the effect of caffeine on Drosophila, most of them conducted using natural populations. However, flies derived from natural populations for longevity studies display substantial variations in longevity (2), most likely brought about by heterogeneous population-specific genetic background. In addition, the genetic instability brought about by an unbalanced genetic background can significantly affect the outcome of a longevity analysis. A good scientific experiment requires fixing of all variables except for the one under investigation. A control-experiment comparison analysis cannot be adequately achieved in longevity analyses involving natural populations due to their inherent genetic variability and, thus, varying genetic background of organisms involved in the study.