Invasion of the Body Snatchers (1956), one of the most successful “B-movies” of all time, has spent the last 60 years under examination as a powerful piece of political allegory. Keenly tuned into the fears of 1950s American society, Invasion of the Body Snatches was, according to Rotten Tomatoes, "one of the best political allegories of the 1950s." In an era when the US feared the spread of communism taking over allies abroad and citizens at home, paranoia naturally permeated many films. Siegel’s picture about vegetable pods from outer space that morph into emotionless replicas of human beings, possessing the bodies of real people while they sleep, seems like an obvious analogy for the nightmare of a strange, deranged ideology taking over our neighbors and loved ones, transforming them into aliens who want to destroy our way of life.

But did the filmmakers actually intend the story as a social parable?

The assumption that Invasion of the Body Snatchers is political allegory is largely unquestioned and well-documented among film resources and criticism. AMC Filmsite writes that the politicized film has inspired interpretations ranging from “paranoia toward the spread of a harmful ideology such as socialistic Communism, or the sweeping mass hysteria of McCarthyism in the 1950s and blacklisting of Hollywood, the spread of an unknown malignancy or virulent germ (read fear of annihilation by 'nuclear war'), or the numbing of our individuality and emotional psyches through conformity and group-think. Yet its main theme was the alien (read 'Communist') dehumanization and take-over of an entire community by large seed pods (found in basements, automobile trunks, a greenhouse, and on a pool table) that replicated and replaced human beings. And it told of the heroic struggle of one helpless but determined man of conscience, a small-town doctor (McCarthy), to vainly combat and quell the deadly, indestructible threat.”

Directed by Don Siegel, Invasion of the Body Snatchers was produced under the supervision of Walter Wanger, who had just been released from prison for attempted murder. Filmed in under three weeks on a menial budget, the film adaptation of Jack Finney’s novel The Body Snatchers was largely ignored by critics on its initial run and only retroactively earned recognition as an influential moment in American cinematic history. The film, which invented the still-used slang term “pod people,” was remade multiple times and has shaped countless films and genres that followed.

Equal parts science fiction and horror, it features little actual science, no monsters and no murders, yet The Missing Slate calls the movie "one of the most multifaceted horror films ever made", arguing that "simultaneously exploiting the contemporary fear of infiltration by undesirable elements as well as a burgeoning concern over homeland totalitarianism in the wake of Senator Joseph McCarthy’s notorious communist witch hunt, it may be the clearest window into the American psyche that horror cinema has ever provided.”

But is all of this neat interpretation merely a retroactive reading that gained popularity with the passage of time? Is the film's story so open-ended and other-worldly that it invites unintended analogies? In an audio interview on the film's 1998 DVD release, the film’s lead actor, Kevin McCarthy, said that he was not aware of any intended political allegory when the film was made. The interviewer on the DVD track claimed that the novel’s author, Jack Finney, also professed no specific political allegory in the original work.

In his autobiography, I Thought We Were Making Movies, Not History, Walter Mirisch defended the film as a piece of entertainment and not a political statement. He said, "People began to read meanings into pictures that were never intended. The Invasion of the Body Snatchers is an example of that. I remember reading a magazine article arguing that the picture was intended as an allegory about the communist infiltration of America. From personal knowledge, neither Walter Wanger nor Don Siegel, who directed it, nor Dan Mainwaring, who wrote the script, nor original author Jack Finney, nor myself, saw it as anything other than a thriller, pure and simple." As an interesting side note, writer Mainwaring was a leftist who was blacklisted from Hollywood at one point during the McCarthy era.

If details in interpretatios vary, most accept that the film is, at least in large part, an allegory for the loss of individual autonomy. What’s perhaps most curious is that Body Snatchers's supposed allegorical message has been linked to both ends of the political spectrum: some have read the film as a reflection of right-wing paranoia about Communists taking over the American way of life, while others see it as symbolic of left-wing paranoia about McCarthyism. It is natural to read what we know of the 1950s into the film: national rhetoric at that time was steeped in anti-communist obsession, and many Americans feared being overtaken by an outside force intent on uniformity. Body Snatchers is easily read as a call to fight back against the mindless conformity of mass society and the soulless aliens who have dialogue like, "Join us - life will be much simpler and better." The general small-town America setting of the film could easily be anyone's home town within the country; thus its image feels distinctly American, rather than belonging to any specific region, and takes on a symbolic resonance for the country as a whole. But while the film is undeniably a portrait of individualism in contest, challenging our national identity and humanity, the social target or political affiliation of the film, if it has any, is not finally clear.

Don Siegel spoke of an existing allegorical subtext but didn’t commit to it being the full purpose of the film. He said, “I felt that this was a very important story. I think that the world is populated by pods and I wanted to show them. I think so many people have no feeling about cultural things, no feeling of pain, of sorrow… The political reference to Senator McCarthy and totalitarianism was inescapable but I tried not to emphasize it because I feel that motion pictures are primarily to entertain and I did not want to preach.”

From the filmmakers' perspective, Invasion of the Body Snatches was meant as good science fiction thriller first. The plot speaks to the themes of mindless conformity and individual automony on a conceptual level, but there is limited evidence to prove that the critique is narrowly aimed at communism, McCarthyism or any particular political philosophy. The story, simple yet haunting enough to support political interpretations from various points of view, arguably speaks to all these ideologies and more. Whatever the filmmakers' original intentions, Invasion of the Body Snatchers was not the first or last film to take on a retroactive social message, but it is undoubtedly one of history's most salient examples of the phenomenon.