Johannes Reinke

Among the German biologists, theoretical biology was initially associated with philosophy of nature, with epistemology and metaphysics, rather than with the formulation of scientific hypotheses.

The botanist Johannes Reinke, who coined the term theoretical biology in 1901 to differentiate it from empirical biology, was himself a proponent of the revived philosophy of neo-vitalism.

Jakob Johann von Uexküll's theoretical biology, published in 1920, was to a large extent also a philosophical work.

Best known for introducing the notion of Umwelt, Uexküll was one of the pioneers of the field of biosemiotics, which studies communication within and between living organisms in terms of signs and codes conveying distinct interpretable meanings.