Gregor Johann Mendel

This Augustinian priest (1822-1884), abbott of his monastery, is also the Father of Genetics. Though farmers had known for centuries that crossbreeding of animals and plants could favor certain desirable traits, Mendel’s pea plant experiments conducted between 1856 and 1863 established many of the rules of heredity, now referred to as the laws of Mendelian inheritance. During his childhood, Mendel worked as a gardener and studied beekeeping. Later, as a young man, he attended gymnasium in Opava (called Troppau in German). From 1840 to 1843, he studied practical and theoretical philosophy and physics at the Philosophical Institute of the University of Olomouc.

When Mendel entered the Faculty of Philosophy, the Department of Natural History and Agriculture was headed by Johann Karl Nestler who conducted extensive research of hereditary traits of plants and animals, especially sheep. Upon recommendation of his physics teacher Friedrich Franz, Mendel entered the Augustinian St Thomas’s Abbey in Brno (called Brünn in German) and began his training as a priest. In 1851, he was sent to the University of Vienna to study under the sponsorship of Abbot C. F. Napp so that he could get more formal education. At Vienna, his professor of physics was Christian Doppler. Mendel returned to his abbey in 1853 as a teacher, principally of physics. In 1867, he replaced Napp as abbot of the monastery.

Gregor was inspired by both his professors at the Palacký University, Olomouc, (Friedrich Franz and Johann Karl Nestler) and his colleagues at the monastery (such as Franz Diebl) to study variation in plants. In 1854, Napp authorized Mendel for the investigation, who conducted his study in the monastery’s 2 hectares (4.9 acres) experimental garden, which was originally planted by Napp in 1830. Unlike Nestler, who studied hereditary traits in sheep, Mendel focused on plants. After initial experiments with pea plants, Mendel settled on studying seven traits that seemed to inherit independently of other traits: seed shape, flower color, seed coat tint, pod shape, unripe pod color, flower location, and plant height. He first focused on seed shape, which was either angular or round. Between 1856 and 1863 Mendel cultivated and tested some 28,000 plants, majority of which were pea plants (Pisum sativum). This study showed that one in four pea plants had purebred recessive traits, two out of four were hybrid and one out of four were purebred dominant. His experiments led him to make two generalizations, the Law of Segregation and the Law of Independent Assortment, which later came to be known as Mendel’s Laws of Inheritance.

Few people realize that Gregor Mendel also studied astronomy and meteorology, founding the ‘Austrian Meteorological Society’ in 1865. In fact, the majority of his published works were related to meteorology, not genetics.

Mendel presented his paper, “Versuche über Pflanzenhybriden” (“Experiments on Plant Hybridization”), at two meetings of the Natural History Society of Brno in Moravia on 8 February and 8 March 1865. During his own lifetime, most biologists held the idea that all characteristics were passed to the next generation through blending inheritance, in which the traits from each parent are averaged together. Darwin read a summary of Mendel, but didn’t understand it, so he ignored it. Mendel read Darwin and instantly knew Darwin’s “blended” inheritance was wrong. Mendel instead hypothesized that each parent contributes some particulate matter to the offspring. He called this heritable substance “elementen.” It was not until the spring of 1900 that independent duplication of his work by Hugo de Vries and Carl Correns, and the rediscovery of Mendel’s writings and laws, led to the realization of the importance of Mendel’s work. In fact, both of his successors acknowledged Mendel’s priority, and it is thought probable that de Vries did not understand the results he had found until after reading Mendel. The combination, in the 1930s and 1940s, of Mendelian genetics with Darwin’s theory of natural selection (Darwin’s erroneous “blended inheritance” ideas were unceremoniously thrown out), resulted in the modern synthesis of evolutionary biology.

While there was an attempt in the late 1990s to assert that Mendel’s original results had been falsified by Mendel’s “confirmation bias”, subsequent studies in 2008 and later by Hartl and Fairbanks (with Allan Franklin and AWF Edwards) concluded that there were no reasons to assert Mendel fabricated his results, nor was there evidence that Fisher, the man who questioned those results, was deliberately trying to diminish Mendel’s legacy. Reassessment of the statistical analyses disproves the notion of “confirmation bias” in Mendel’s results. This Augustinian priest’s work now stands, untarnished, as the seminal work in genetic inheritance.