Ernst Haeckel

Ernst Heinrich Philipp August Haeckel (1834–1919) was a German zoologist, naturalist, philosopher, physician, professor, marine biologist, artist, and eugenicist. He named thousands of new species, created a genealogical tree linking all life, and introduced terms like ecology, phylum, phylogeny, ontogeny, and Protista. A key promoter of Darwin’s ideas in Germany, Haeckel formulated the recapitulation theory—often summarized as “ontogeny recapitulates phylogeny”—which he later expanded into his “Biogenetic Law.” This law incorrectly claimed that an organism’s development mirrors its species’ evolutionary history, supported by drawings of human embryos that may have been intentionally falsified or simply poorly executed. Haeckel’s *Kunstformen der Natur* featured over 100 detailed, multicolored illustrations of animals and sea creatures, influencing the Art Nouveau movement. As a philosopher, he wrote *Die Welträthsel* (1895–1899), which popularized the term “world riddle,” and *Freedom in Science and Teaching* to advocate for teaching evolution. He also coined the “Biogenetic Law.” Haeckel promoted scientific racism and Social Darwinism, and in 1914 he became the first person to describe the Great War as the “first” World War. Born in Potsdam, Prussia, in 1834, Haeckel attended the Domgymnasium in Merseburg before studying medicine in Berlin and Würzburg under notable figures like Albert von Kölliker, Franz Leydig, Rudolf Virchow, and Johannes Peter Müller. He earned his medical doctorate in 1857 and a license to practice, but found the work unfulfilling. After studying under Carl Gegenbaur at Jena, he habilitated in comparative anatomy in 1861 and became a zoology professor there, a post he held for 47 years. From 1859 to 1866, he worked on radiolarians, sponges, and segmented worms, naming nearly 700 radiolarian species during a Mediterranean trip. In 1866–1867, Haeckel traveled to the Canary Islands with Hermann Fol, then visited Charles Lyell, Thomas Huxley, and Charles Darwin in England. He married Agnes Huschke in 1867; they had three children. He later researched in Norway, Croatia (living in a monastery on Hvar), and Egypt, Turkey, and Greece. In 1907, he built a museum in Jena to teach evolution, retired in 1909, and left the Evangelical Church in 1910. His first wife, Anna Sethe, died in 1864; he named beautiful jellyfish species after her. Agnes died in 1915, after which Haeckel became frail, breaking a leg and arm. He sold his Villa Medusa in 1918 to the Carl Zeiss foundation, which kept his library. He died on 9 August 1919. Haeckel advocated monism—a pantheistic, impersonal view that God is in all things—in *Monism as Connecting Religion and Science* (1892). He co-founded the Monist League in 1906, which opposed philosophical materialism and promoted a “natural Weltanschauung”; it lasted until 1933 and included members like Wilhelm Ostwald and Helene Stöcker. Politically, Haeckel blended German Romanticism with a form of Lamarckism, seeing social sciences as “applied biology”—a phrase later used in Nazi propaganda.