Mendel and the Birth of Genetics

Gregor Mendel, an Augustinian friar, spent the years between 1856 and 1863 conducting meticulous breeding experiments with pea plants (Pisum sativum) in the garden of his monastery in Brno, in the present-day Czech Republic. By tracking traits such as seed shape, seed color, flower color, and plant height across generations of carefully controlled crosses, Mendel identified statistical patterns that revealed the existence of discrete hereditary units, later called genes, which are passed from parents to offspring according to predictable rules. His law of segregation held that each organism carries two copies of each hereditary factor, one inherited from each parent, which separate during the formation of reproductive cells, while his law of independent assortment showed that different traits are typically inherited independently of one another. Mendel also distinguished between dominant traits, which mask the presence of a second, recessive version of a gene, and recessive traits, which only appear when both inherited copies match. He published his findings in 1866 as "Versuche uber Pflanzen-Hybriden," but the work attracted little attention during his lifetime.