Austrian monk Gregor Johann Mendel (1822–1884) performed experiments with pea plants from 1857 to 1865 that eventually led to his discovery of the laws of heredity. Gathering 34 different kinds of peas of the genus Pisum (all tested for their purity), he attempted to determine the possibility of producing new variants by cross-breeding. By self-pollinating the plants—and covering them over so there was no unplanned cross-pollination—he determined the detailed characteristics of their offspring, such as height and color.

A simple Mendelian matrix.

Prior to Mendel, scientists believed that heredity characteristics of a species were the result of a blending process, and that over time various parental characteristics were diluted. Mendel showed that characteristics actually followed a set of specific hereditary laws. He worked out what can be described as a mathematical matrix of the characteristics, thus determining what characteristics were dominant and recessive in the plants. (For more about matrices, see “Algebra.”)

But Mendel had a hard time getting his results published. Even after publication by a local natural history society, his work was ignored. Mendel gave up both gardening and science when he was promoted to abbot. Coincidentally, and amazingly, by 1900 three different biologists working in three different countries—Hugo de Vries in the Netherlands, Erich Tschermak von Seysenegg in Austria, and Karl Correns in Germany—determined the hereditary laws independently. But they all knew about Mendel’s work, graciously giving the credit for the findings to him. Mendel, rightfully, is now commonly considered the “father of genetics.”