In 1961, Leonard Hayflick and his colleague cytogeneticist Paul Moorhead conducted a series of definitive experiments in which they were able to demonstrate that normal human somatic cells have a finite number of replicative cycles. Today this phenomenon is known as the Hayflick Limit. In order to rule out any technical errors due to methodology or contamination, the two scientists mixed equal numbers of male cells, that had replicated many times, with female cells that had only replicated a few times. Unmixed cell cultures were used as controls. Once the male control cells stopped replicating they examined the mixed population of cells and found only female cells left. The results of this experiment disputed accepted dogma of the time that all normal vertebrate cells grown in culture were immortal and to this day there are still some skeptical scientists. In fact, the paper that resulted from their work was...