Haeckel, Ernst Heinrich Philipp August (1834–1919)

German zoologist and philosopher. His theory of ‘recapitulation’, expressed as ‘ontogeny repeats phylogeny’ (or that embryonic stages represent past stages in the organism's evolution), has been superseded, but it stimulated research in embryology.

Haeckel was born in Potsdam, Prussia, and studied at Würtzburg and Berlin. He was professor at Jena 1865–1909.

In 1866, the same year that he met Charles Darwin, Haeckel introduced a method, still used today, of representing evolutionary history, or phylogeny, by means of treelike diagrams.

Haeckel tried to apply Darwin's doctrine of evolution to philosophy and religion. He denied the immortality of the soul, the freedom of the will, and the existence of a personal God. His view that the origin of life lies in the chemical and physical factors of the environment, such as sunlight, oxygen, water, and methane, has been shown to be likely. He coined the term ‘ecology’, and published best-selling general scientific works such as Welträtsel/The Riddles of the Universe (1899).