The basis for the movie “Soylent Green” was Harry Harrison’s story “Make Room, Make Room” which was published in 1966 two years before Paul Ehrlich’s 1968 “Population Bomb”.
Thanks for the correction, if indeed it is correct (never heard of a base story for the movie).
The movie had Malthusian themes. Malthus’ “An Essay on the Principle of Population” is of course much older than all of this (published 1798).
The movie COINCIDENTALLY came out around the big environmental nuttiness of hippies, when Malthusianism was the big thing. Morphed into Earth Day, Gaia Hypothesis, you name it. Of course by the 1970s it was GLOBAL COOLING that was going to kill us all.