sentences:  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"