http://www.sciencemag.org/news/2018/07/monkey-inspiration-dr-seuss-s-lorax

Theodor “Dr. Seuss” Geisel’s beloved picture-book ode to environmentalism is set in a fictional land of thneeds and truffula trees, but The Lorax may have a real-world counterpart. The orange, mustachioed titular character (left) may have been based on the now-threatened patas monkey (Erythrocebus patas, right), scientists report today.

Geisel wrote 90% of The Lorax while visiting the Mount Kenya Safari Club in Nanyuki, Kenya, a region inhabited by patas monkeys. The researchers have no direct proof that the author encountered the animal during his stay, but his autobiography mentions that he likened the shape of Kenyan trees to his own style of illustration. He also included an illustration of what could be a whistling thorn acacia (Acacia drepanolobium) in The Lorax—a tree which the patas monkeys depend on for more than three-quarters of their diet.