Mendel :

Mendel, Gregor Johann (1822-1884), Austrian monk, whose experimental work became the basis of modern heredity theory.
Mendel was born on July 22, 1822, to a peasant family in Heinzendorf (now Hynèice, Czech Republic). In 1843 he entered the Augustinian monastery at Brünn (now Brno, Czech Republic), which was known as a centre of learning and scientific endeavour. He studied science as well as theology, and later attended the University of Vienna. On his return to Brünn he taught for a time at the local technical school and became actively engaged in investigating variation, heredity, and evolution in plants at the monastery’s experimental garden.
Between 1856 and 1863 Mendel cultivated and tested at least 28,000 pea plants, carefully analysing the inheritance patterns of seven pairs of seed and plant characteristics. He had an interest in hybridization, and was probably experimenting to determine whether new plant species could be obtained through hybridization. From an early stage in his work, he came to believe that characteristics are not inherited through a simple blending of paternal and maternal attributes. To account for the inheritance patterns observed between generations, he enunciated two generalizations that later became known as the laws of heredity. The first was that there were hereditary units (now known as genes) that often expressed dominant and recessive characteristics. When egg and sperm unite, forming a gene pair, the dominant gene masks the recessive gene. The second generalization was that hereditary units did not blend, but remained unchanged from one generation to another, and that the expression of a hereditary unit for any single characteristic is usually not influenced by the expression of another. See Mendel’s Laws and Genetics.

Mendel published his important work on heredity in 1866. Despite, or perhaps because of, its descriptions of large numbers of experimental crosses that allowed him to express his results numerically and subject them to statistical analysis, this work made virtually no impression for the next 34 years. Only in 1900 was his work recognized more or less independently by three investigators, one of whom was the Dutch botanist Hugo De Vries, and not until the late 1920s was its full significance realized, particularly in relation to evolutionary theory. As a result of years of research in population genetics, investigators were able to demonstrate that Darwinian evolution can be described in terms of the change in gene frequency of Mendelian pairs of characteristics in a population over successive generations.

Mendel himself published only one further scientific paper after 1866. This concerned his inconclusive hybridization experiments with the hawkweed Hieracium, although he continued an important correspondence with the botanist Carl von Naegeli. In 1868 Mendel was elected abbot of his monastery, and he spent the last years of his life carrying out his administrative duties.