From a 1973 perspective, Soylent Green imagines the world in 2022, where the temperature is stifling owing to the greenhouse effect, and where overpopulation has reached critical proportions.  Only the very rich and well-connected eat what for us is ordinary food, while the vast majority must eat crackers of different colors indicating their quality, with green being the most desirable because it is the most nutritious.  Even water is rationed.  And electric power is unreliable.

Detective Thorn (Charlton Heston) is basically a good cop, but when investigating the crime scenes of rich victims, he does a little looting, mostly taking items of food, like beefsteak, vegetables, and liquor, and he also helps himself to whatever prostitute, referred to as “furniture,” happens to be attached to the luxury apartment.

We see Thorn having to struggle to walk up the steps to his apartment, because there are so many people sleeping on the stairs.  Later, when a riot starts because there is a shortage of Soylent Green wafers, we see dump trucks called “scoops” being used to remove people from the streets.

Thorn investigates the murder of Simonson (Joseph Cotton), which he suspects is an assassination.  Thorn’s assistant, referred to as a “book,” on account of his ability to do research on old written material, is Sol (Edward G. Robinson).  Sol learns a terrible secret and decides to end it all by going to a euthanasia center, where he gets to look at scenes of nature as it once was and listen to beautiful music for twenty minutes before dying from some concoction he imbibed.  Prior to this, he tells Thorn that the plankton used to make Soylent Green is disappearing from the oceans.  As a substitute for the loss of plankton, people that die are secretly processed and turned into the Soylent Green wafers.

The theme of this movie is ick.  Rich men are obnoxious, and we resent the way they are so privileged and arrogant.  The image of old people walking into euthanasia centers to end their lives is creepy.  And the use of human flesh to make edible wafers is disturbing.  Setting aside the fact that cannibalism can lead to the transmission of abnormal prions as in Creutzfeldt-Jakob disease, the main objection to using human flesh for consumption is that the idea of it is repulsive.  But in a world that is overpopulated and in which there is a food shortage, such a solution may actually be rational.  After all, we are not talking about the kind of cannibalism where we have a bunch of savages standing around a pot with a missionary in it.  The people being turned into food either died naturally or, in the case of the euthanasia centers, voluntarily.  So, the worst you can say about such a world is that it makes us feel a little queasy.

Nevertheless, the movie should have simply ended with this revelation about Soylent Green.  Instead, in an apparent effort to make the whole business more insidious, Thorn tells his supervisor, “They’re making our food out of people.  Next thing, they’ll be breeding us like cattle.”  Unfortunately, this line, which is supposed to make us even more horrified by what is going on, only makes us groan at its absurdity.  In a world where there are too many people, it makes no sense to breed more.  You just eat the ones you have.  Furthermore, according to my rough, back-of-the-envelope calculations, you would have to feed people at least five times as much protein to raise them as you would get out of them once you brought them to slaughter.  Because this idea of breeding people is illogical, it turns what would have been a believable, pessimistic vision of the future into something so silly we can only snort with contempt.