Gregor Mendel was the first person to make precise observation about the biological mechanism of inheritance. This happened a little 100 years ago in Austria, Where Mendel spent his leisure hours performing experiments with pea plants of different types. He crossed them carefully and took notes about the appearance of various traits, or characteristics in succeeding generations. From his observations, Mendel formed a set of rules, now known as the Mendelian Lows of Inheritance, which were found to apply not only to plants but to animals and human beings as well. This was the beginning of the modern science of genetics.