Paul Howe Shepard, Jr. (June 12, 1925 – July 27, 1996) was an American environmentalist and author best known for introducing the "Pleistocene paradigm" to deep ecology.
He went on to earn a doctorate from Yale, and his 1967 book Man in the Landscape: a Historic View of the Esthetics of Nature was based on his thesis.
Based on his early study of modern ethnographic literature examining contemporary nature-based peoples, Shepard created a developmental model for understanding the role of sustained contact with nature in healthy human psychological development, positing that humans, having spent 99% of their social history in hunting and gathering environments, are therefore evolutionarily dependent on nature for proper emotional and psychological growth and development.
Drawing from ideas of neoteny, Shepard postulated that many humans in post-agricultural society are often not fully mature, but are trapped in infantilism or an adolescent state.
[2] Some of his most influential books are The Tender Carnivore and the Sacred Game, Nature and Madness, Coming Home to the Pleistocene, Where we Belong, and the Others.