July 20, 1822 (a Saturday)

The earliest known photograph of Gregor Mendel.

On this date, Gregor Johann Mendel was born (the day he was baptized, July 22nd, is often given erroneously as his birthday). He performed a series of beautifully designed experiments on pea plants over a period of seven years, from 1856 to 1863, to discover the principles of heredity. His studies were the first to focus on the numerical relationships among traits appearing in the progeny of hybrids; and his interpretation, clear and concise, was based on material hereditary elements that undergo segregation and independent assortment. Mendel delivered two lectures on the results of his experiments at the meetings of the Society of Natural Sciences in Brünn, Austria on February 8th and March 8th in 1865. He turned these lectures into a (long) paper, published in the 1866 issue of the Proceedings of the Society, but it received little notice. Mendel apparently even sent one of his scientific papers to Darwin, but Darwin never bothered to read it. Mendel abandoned his experiments in the 1860s after he was appointed abbot of his monastery and his time was taken up in administrative duties.

The importance of Mendel’s work was not recognized until about thirty years after the publication of his seminal paper, when Hugo de Vries in 1900 in Holland, William Bateson in 1902 in Great Britain, Franz Correns in 1900 in Germany, and Erich Tschermak in 1901 in Austria were all to acknowledge Mendel’s legacy, and hail him as the true “father” of classical genetics.