Ernst Heinrich Philipp August Haeckel (German: [ˈhɛkəl]; 16 February 1834 – 9 August 1919) was a German biologist, naturalist, philosopher, physician, professor, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, includinganthropogeny, ecology, phylum, phylogeny, stem cell, and Protista.
Haeckel promoted and popularised Charles Darwin’s work in Germany and developed the influential but no longer widely held recapitulation theory (“ontogeny recapitulates phylogeny”) claiming that an individual organism’s biological development, or ontogeny, parallels and summarises its species’ evolutionary development, or phylogeny.
The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures (see: Kunstformen der Natur, “Art Forms of Nature”). As a philosopher, Ernst Haeckel wrote Die Welträtsel (1895–1899; in English: The Riddle of the Universe, 1901), the genesis for the term “world riddle” (Welträtsel); and Freedom in Science and Teaching to support teaching evolution.
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 ofevolutionary 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.
He was one of the first to consider psychology as a branch of physiology. He also proposed the kingdom Protista in 1866. His chief interests lay in evolution and life development processes in general, including development of nonrandom form, which culminated in the beautifully illustrated Kunstformen der Natur (Art forms of nature). Haeckel did not support natural selection, rather believing in Lamarckism.
Haeckel advanced a version of the earlier recapitulation theory previously set out by Étienne Serres in the 1820s and supported by followers of Étienne Geoffroy Saint-Hilaireincluding Robert Edmond Grant. It proposed a link between ontogeny (development of form) and phylogeny (evolutionary descent), summed up by Haeckel in the phrase “ontogeny recapitulates phylogeny”. His concept of recapitulation has been refuted in the form he gave it (now called “strong recapitulation”), in favour of the ideas first advanced by Karl Ernst von Baer. The strong recapitulation hypothesis views ontogeny as repeating forms of the ancestors, while weak recapitulation means that what is repeated (and built upon) is the ancestral embryonic development process. Haeckel supported the theory with embryo drawings that have since been shown to be oversimplified and in part inaccurate, and the theory is now considered an oversimplification of quite complicated relationships. Haeckel introduced the concept of heterochrony, the change in timing of embryonic development over the course of evolution.
Haeckel was a flamboyant figure, who sometimes took great, non-scientific leaps from available evidence. For example, at the time when Darwin published On the Origin of Species by Means of Natural Selection (1859), Haeckel postulated that evidence of human evolution would be found in the Dutch East Indies (now Indonesia). At that time, no remains of human ancestors had yet been identified. He described these theoretical remains in great detail and even named the as-yet unfound species, Pithecanthropus alalus, and instructed his students such as Richard and Oskar Hertwig to go and find it.
One student did find some remains: a Dutchman named Eugène Dubois searched the East Indies from 1887 to 1895, discovering the remains of Java Man in 1891, consisting of a skullcap, thighbone, and a few teeth. These remains are among the oldest hominid remains ever found. Dubois classified Java Man with Haeckel’s Pithecanthropus label, though they were later reclassified as Homo erectus. Some scientists of the day suggested Dubois’ Java Man as a potential intermediate form between modern humans and the common ancestor we share with the other great apes. The current consensus of anthropologists is that the direct ancestors of modern humans were African populations ofHomo erectus (possibly Homo ergaster), rather than the Asian populations exemplified by Java Man and Peking Man.
“The whole of organic nature on our planet exists only by a relentless war of all against all. … The raging war of interests in human society is only a feeble picture of an unceasing and terrible war of existence which reigns throughout the whole of the living world.”
Kunstformen der Natur