Tiedemann devoted himself to the study of natural science, and upon moving to Paris, became an ardent follower of Georges Cuvier.

On his return to Germany, he advocated for anatomical research and aligned himself with the emerging field of experimental natural science.

His staunch empiricism placed him at odds with contemporary adherents of romantic Naturphilosophie, such philosopher Friedrich Wilhelm Joseph von Schelling and naturalist Lorenz Oken.

He further contested the notion that "there is any innate difference in the intellectual faculties of these two varieties of the human race" and attributed the perceived inferiority of black people to the deleterious effects of slavery and colonialism.

[10] Science historian Robert J. Richards has written that Tiedemann "joined the basic notion of species evolution, of a Lamarckian flavor, with the proposition that higher animals in their embryological development recapitulated the morphological stages of those lower in the scale.

"[11] Writing in 1913, Hans Gadow noted that Tiedemann in 1814 had identified a basic function of sexual selection in preventing less fit males from propagating, and fossils as showing gradual metamorphosis of species over geological time.