Plant evolutionary tree by Haeckel, 1874. This evolutionary tree describes the evolution of plants through prehistoric time (timescale down left). In his studies on evolution, German naturalist Ernst Haeckel (1834-1919) incorrectly gave the impression through trees like this that mammals in general, and humans in particular, are the most highly evolved organisms. This page is from an 1874 edition of Haekel's work 'Naturliche Schopfungsgeschichte' (The History of Creation), first published in 1868.