Pisum sativum (Illustration taken from Mendel’s book on inheritance).

“One of the most fascinating aspects of Mendel’s paper is his success in describing the patterns of inheritance, without having any knowledge about the biological mechanisms responsible for those patterns. Although it was well-known by 1865 that peas, like all plants and animals, were made up of cells, Mendel had no knowledge of what the genetic material of the cell could be. More importantly, perhaps, he didn’t have the language of genetics to reason about such things.

Mendel’s use of mathematics (the combination series in particular) is important in this respect, because mathematics made it easy to avoid questions of biological mechanism. When he was forced to go beyond mathematics and to use natural language to describe what he saw, his description problems became more difficult. A nice example of the difficulty is seen in his use of the strange phrase “must impress their peculiarity upon” (Eigentümlichkeit aufprägen müssen), to describe dominance.”–Via.

The following videos, three of them, summarize Mendel’s most important claims on inheritance. Many of his discoveries, as you will notice while watching these videos, are still useful to understand important things about ourselves, such as our blood type: