Gregor Johann Mendel

1822-1884

Austrian Monk, Biologist and Botanist

In the quiet setting of a monastery garden, Gregor Mendel bred pea plants in an attempt to understand heredity, or how characteristics are passed from parent to offspring. After more than seven years of research, Mendel deciphered the basic principles governing heredity (now called Mendelian laws). Although Mendel's work was not appreciated until 16 years after his death, the results of his experiments and his interpretation of those results ultimately provided the foundation for the field of genetics, and he is considered the father of the discipline.

Gregor Mendel was born Johann Mendel in Heinzendorf, Moravia, in 1822. He was the second child of Anton and Rosine Mendel, who were peasant farmers. In order to be educated, Mendel joined an Augustinian monastery in Brünn, Austria (now Brno, Czech Republic) in 1843, and there he took the name of Gregor and became an ordained priest in 1848. Mendel left the monastery briefly to study mathematics, physics, and science at the University of Vienna from 1851 to 1853.

Despite Mendel's intellect and the lasting significance of his future findings, he repeatedly failed the tests required to obtain a teaching certificate (although he did serve as a substitute teacher at local schools and taught experimental physics and natural history at the Brünn Modern School for 14 years). This failing, however, did not discourage his love of the natural world around him. He was an amateur scientist with interests as diverse as meteorology, botany, and theories of evolution, and he read the scientific literature of the day. He was an astute observer and grew curious about how plants in the monastery garden obtained unusual characteristics. With questions about inheritance in mind, Mendel began in 1856 the experiments for which he is now famous.

That plants and animals could be bred to produce hybrids with desirable characteristics was known long before Mendel came along. However, Mendel's quantitative approach to studying heredity, in which he carefully designed experiments and mathematically analyzed the data, was new; it was this approach that allowed him to recognize the patterns underlying heredity and to develop a theory to explain them. His decision to study pea plants also was crucial to the success of his work. The pea plant normally self-pollinates, meaning that male gametes fertilize female gametes from the same plant; this feature meant that Mendel could carefully control reproduction and artificially cross plants with different characteristics. Mendel's pea plants also had a number of clearly defined and measurable traits (e.g. seed color, stem length), seven of which he studied in a logical progression of experiments in which he crossed plants with different sets of traits.

After spending years studying more than 21,000 pea plants, Mendel recognized that he could predict the outcome of breeding in successive generations based on mathematical probabilities. Mendel did not know about genes, chromosomes, and DNA, but from his experiments he deduced that two hereditary "units" (now known to be genes) determine a given trait, that one comes from each parent, and that one exhibits dominance over the other. What came to be called Mendel's law of segregation states that every individual carries pairs of factors for each trait and that members of the pair separate during gamete formation. Mendel also found that different traits were passed to offspring independently of one another, which led to the law of independent assortment. This law states that members of each pair of factors are distributed independently when gametes are formed.

Mendel published his manuscript, Experiments with Plant Hybrids, in the Proceedings of the Brünn Natural History Society in 1866, but it remained unappreciated during his lifetime. Mendel spent the remainder of his life devoted to the monastery, where he became abbot in 1868. It was not until the turn of the twentieth century that three scientists independently discovered the significance of Mendel's work as an explanation for how inheritance works. Since then, geneticists have shown that there are many exceptions to Mendel's rules. However, Mendel's discoveries hold true for the inheritance of many characteristics in plants and animals and provide the foundation for our current understanding of genetics.

LYNN M.L. LAUERMAN