To reject biorhythms, some might say, is to totally ignore science. In the same way, the theory of evolution is based on observable scientific fact. Specifically, some variation in existing species can, and does, occur through selective breeding. This is called microevolution. No creationist organization that we know of denies the existence of microevolution.
Microevolution is just as much a part of reality as menstruation is.
Many incorrect conclusions are based on true foundations. Biorhythm calculators and the theory of evolution are two examples. We don t want to spend too much time debunking biorhythms. That isn t our goal. But we do need to show how the logic behind the development of the biorhythm theory is similar to the logic behind the theory of evolution, and why both are incorrect.