Ernst Heinrich Philipp August Haeckel (; German: [ɛʁnst ˈhɛkl̩]; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms and coined many terms in biology, including ecology, phylum, phylogeny, ontogeny, and Protista. Haeckel promoted and popularised Charles Darwin's work in Germany and developed the disproven but influential recapitulation theory (summed up by the dictum "ontogeny recapitulates phylogeny"), later generalizing it into the so called "Biogenetic Law". He wrongly claimed that an individual organism's biological development, or ontogeny, parallels and summarizes its species' evolutionary development, or phylogeny, using incorrectly drawn images of human embryonic development to derive the law. Whether they were intentionally falsified, or drawn poorly by accident is a matter of debate.
The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures, collected in his Kunstformen der Natur ("Art Forms in Nature"), a book which would go on to influence the Art Nouveau artistic movement. As a philosopher, Ernst Haeckel wrote Die Welträthsel (1895–1899; in English: The Riddles of the Universe, 1900), the genesis for the term "world riddle" (Welträtsel); and Freedom in Science and Teaching to support teaching evolution. He also coined the "Biogenetic Law".
Haeckel promoted scientific racism and embraced the idea of Social Darwinism. He was the first person to characterize the Great War as the "first" World War, which he did as early as 1914.
Ernst Haeckel was born on 16 February 1834, in Potsdam (then part of the Kingdom of Prussia).
In 1852, Haeckel completed studies at the Domgymnasium, the cathedral high-school of Merseburg. He then studied medicine in Berlin and Würzburg, particularly with Albert von Kölliker, Franz Leydig, Rudolf Virchow (with whom he later worked briefly as assistant), and with the anatomist-physiologist Johannes Peter Müller (1801–1858). Together with Hermann Steudner he attended botany lectures in Würzburg. In 1857 Haeckel attained a doctorate in medicine, and afterwards he received the license to practice medicine. The occupation of physician appeared less worthwhile to Haeckel after contact with suffering patients.
Haeckel studied under Carl Gegenbaur at the University of Jena for three years. In 1861 he earned a habilitation in comparative anatomy and became a professor of zoology at the University of Jena, where he remained for 47 years, from 1862 to 1909. Between 1859 and 1866, Haeckel worked on many phyla, such as radiolarians, poriferans (sponges) and annelids (segmented worms). During a trip to the Mediterranean, Haeckel named nearly 700 new species of radiolarians.
From 1866 to 1867 Haeckel made an extended journey to the Canary Islands with Hermann Fol. On 17 October 1866 he arrived in London. Over the next few days he met Charles Lyell, and visited Thomas Huxley and family at their home. On 21 October he visited Charles Darwin at Down House in Kent. In 1867 he married Agnes Huschke. Their son Walter was born in 1868, their daughters Elizabeth in 1871 and Emma in 1873. In 1869 he traveled as a researcher to Norway, in 1871 to Croatia (where he lived on the island of Hvar in a monastery), and in 1873 to Egypt, Turkey, and Greece. In 1907 he had a museum built in Jena to teach the public about evolution. Haeckel retired from teaching in 1909, and in 1910 he withdrew from the Evangelical Church of Prussia.
On the occasion of his 80th birthday celebration he was presented with a two-volume work entitled Was wir Ernst Haeckel verdanken (What We Owe to Ernst Haeckel), edited at the request of the German Monistenbund by Heinrich Schmidt of Jena.
In 1864, his first wife, Anna Sethe, died. Haeckel dedicated some species of jellyfish that he found beautiful (such as Desmonema annasethe) to her.
Haeckel's second wife, Agnes, died in 1915, and he became substantially frailer, breaking his leg and arm. He sold his "Villa Medusa" in Jena in 1918 to the Carl Zeiss foundation, which preserved his library.
Haeckel died on 9 August 1919.
In Monism as Connecting Religion and Science (1892), he argued in favor of monism as the view most compatible with the current scientific understanding of the natural world. His perspective of monism was pantheistic and impersonal. The monistic idea of God, which alone is compatible with our present knowledge of nature, recognizes the divine spirit in all things. It can never recognise in God a "personal being," or, in other words, an individual of limited extension in space, or even of human form. God is everywhere.
Haeckel became the most famous proponent of monism in Germany.
In 1906 Haeckel belonged to the founders of the Monist League (Deutscher Monistenbund), which took a stance against philosophical materialism promoting a "natural Weltanschauung". This organization lasted until 1933 and included such notable members as Wilhelm Ostwald, Georg von Arco (1869–1940), Helene Stöcker and Walter Arthur Berendsohn.
Haeckel's affinity for the German Romantic movement, coupled with his acceptance of a form of Lamarckism, influenced his political beliefs. Rather than being a strict Darwinian, Haeckel believed that the characteristics of an organism were acquired through interactions with the environment and that ontogeny reflected phylogeny. He saw the social sciences as instances of "applied biology", and that phrase was picked up and used for Nazi propaganda.
He was the first person to use the term "first world war" about World War I.
However, Haeckel's books were banned by the Nazi Party, which refused Monism and Haeckel's freedom of thought. Moreover, it is worth mentioning that Haeckel had often overtly recognized the great contribution of educated Jews to the German culture.
Haeckel was a zoologist, an accomplished artist and illustrator, and later a professor of comparative anatomy. Although Haeckel's ideas are important to the history of evolutionary theory, and although he was a competent invertebrate anatomist most famous for his work on radiolaria, many speculative concepts that he championed are now considered incorrect. For example, Haeckel described and named hypothetical ancestral microorganisms that have never been found.