Human evolutionary tree by Haeckel, 1895. In his studies on evolution, German naturalist Ernst Haeckel (1834-1919) incorrectly gave the impression through various forms of evolutionary trees that mammals in general, and humans in particular, are the most highly evolved organisms. He also incorrectly applied this principle to different human cultures and groupings, as shown here. This page is from Haeckel's 'Systematische Phylogenie' (Systematic Phylogeny, 1895).