The 2006 film Children of Men was critically acclaimed for its realism and unusual approach to science-fiction. While the film deviated from the book in several important ways, the film was well-reviewed by both critics and by P.D. James, who wrote the original. There are many detailed analyses of the movie's themes and intent, most focusing on the role of children in modern society and how the need to propagate and continue informs and drives the human species. The loss of children removes any ultimate purpose of humanity, as without children there is nothing to leave humanity's work to; with no future generation to continue working where the previous generation left off, literature, art, and science have no larger purpose than the immediate. Another theme in the film is brutality; without the instinctive drive to protect one's self for current or future children, humanity's instinct for self-preservation vanishes. Without a purpose to survival, humanity reverts to animal instincts, killing indiscriminately because there is no point to survival. Since the Earth's birth rates are dropping every year, both the book and film remain relevant today.