Ernst Haeckel, much like Herbert Spencer, was always quotable, even when wrong. Although best known for the famous statement “ontogeny recapitulates phylogeny”, he also coined many words commonly used by biologists today, such as phylum, phylogeny, and ecology. On the other hand, Haeckel supposedly stated that “politics is applied biology” [Not everyone agrees with this, and it may indeed be a fabrication. – e.Ed], a quote used by Nazi propagandists. The Nazi party, rather unfortunately, used not only Haeckel's quotes, but also Haeckel's justifications for racism, nationalism and social darwinism.

Although trained as a physician, Haeckel abandoned his practice in 1859 after reading Darwin's Origin of Species. Always suspicious of teleological and mystical explanation, Haeckel used the Origin as ammunition both to attack entrenched religious dogma and to build his own unique world view.

Hackel studied under Carl Gegenbauer in Jena for three years before becoming a professor of comparative anatomy in 1862. Between 1859 and 1866, he worked on many “invertebrate” groups, including radiolarians, poriferans (sponges) and annelids (segmented worms). He named nearly 150 new species of radiolarians during a trip to the Mediterranean. “Invertebrates” provided the fodder for most of his experimental work on development, leading to his “law of recapitulation”. Haeckel was also a free-thinker who went beyond biology, dabbling in anthropology, psychology, and cosmology. Haeckel's speculative ideas and possible fudging of data, plus lack of empirical support for many of his ideas, tarnished his scientific credentials. However, he remained an immensely popular figure in Germany and was considered a hero by his countrymen.