IntroductionDuring the American Civil War, and at about the time Darwin was proposing his theory of evolution (see Chapter 20), a monk in what is now the Czech Republic was growing peas in the Abby gardens. Gregor Mendel was using them to unlock the secrets of inheritance.
No one prior to Mendel had undertaken a systematic study to gain insight into how traits are passed from one generation to the next. Breeders of plants and animals were well aware of certain characteristics of inheritance, but there was no theory or explanation of how traits were transmitted from parent to offspring. Mendel advanced our knowledge of the field tremendously, and his principles and theories have been shown to be valid over and over again. We still use his methodologies today.
Mendel was successful for several reasons. First, his choice of the garden pea provided him with an ideal model system. The traits Mendel observed in the peas were easy to score and only had two variations; for example, flowers were either white or purple, plants were either tall or short, and seeds were either wrinkled or round. Plants with different traits could be interbred and huge numbers of progeny could be obtained for analysis. But, perhaps more importantly than his choice of a model system, Mendel kept meticulous records, and he used mathematics to analyze his data.