from numbness and nausea to paralysis — particularly of the muscles of the diaphragm — unconsciousness, and death, but do not include a stiffened gait or a deathlike trance. According to psychologist Terence Hines, the scientific community dismisses tetrodotoxin as the cause of this state, and Davis' assessment of the nature of the reports of Haitian zombies is viewed as overly credulous. Social Scottish psychiatrist R. D. Laing highlighted the link between social and cultural expectations and compulsion, in the context of schizophrenia and other mental illness, suggesting that schizogenesis may account for some of the psychological aspects of zombification. Particularly, this suggests cases where schizophrenia manifests a state of catatonia. Roland Littlewood, professor of anthropology and psychiatry, published a study supporting a social explanation of the zombie phenomenon in the medical journal The Lancet in 1997. The social explanation sees observed cases of people identified as zombies as a culture-bound syndrome, with a particular cultural form of adoption practiced in Haiti that unites the homeless and mentally ill with grieving families who see them as their "returned" lost loved ones, as Littlewood summarizes his findings in an article in Times Higher Education: Modern archetype evolution Pulliam and Fonseca (2014) and Walz (2006) trace the zombie lineage back to ancient Mesopotamia. In the Descent of Ishtar, the goddess Ishtar threatens: She repeats this same threat in a slightly modified form in the Epic of Gilgamesh. One of the first books to expose Western culture to the concept of the voodoo zombie was The Magic Island (1929) by W. B. Seabrook. This is the sensationalized account of a narrator who encounters voodoo cults in Haiti and their resurrected thralls. Time commented that the book "introduced 'zombi' into U.S. speech". Zombies have a complex literary heritage, with antecedents ranging from Richard Matheson and H. P. Lovecraft to Mary Shelley's Frankenstein drawing on European folklore of the undead. Victor Halperin directed White Zombie (1932), a horror film starring Bela Lugosi. Here zombies are depicted as mindless, unthinking henchmen under the spell of an evil magician. Zombies, often still using this voodoo-inspired rationale, were initially uncommon in cinema, but their appearances continued sporadically through the 1930s to the 1960s, with films including I Walked with a Zombie (1943) and Plan 9 from Outer Space (1959). Frankenstein by Mary Shelley, while not a zombie novel per se, foreshadows many 20th century ideas about zombies in