From Modern Mythology:
Our standard movie monsters deviate from their early folkloric roots in a number of major ways, but the most notable might be the general move from bewitchment to infection: where strigoi, revenants, zombi, and loup-garou are generally the result of targeted curses, post-Universal-era vampires, zombies, and werewolves are created by being bitten.
We might blame this on the general demystification of western culture, where belief in the ability to be cursed by a witch is rare — and where even self-described witches often consider curses prohibitively dangerous to the caster— or on contagion being a more visually interesting mechanism in film, (though I would argue against this, citing the use of curses in J-horror and post-Suspiria Giallo, not to mention high-budget fantasy like Harry Potter). Instead, contagion spread because in an age of mass-media propaganda and heterogeneous populations, it’s a more flexible metaphor for our political anxieties.
This innovation, the idea of monstrous contagion (which probably can be credited to Stoker), has its most interesting manifestation in the zombie apocalypse narrative.
Political ideas are, functionally, heuristics about how best to run the world. Such heuristics can be reasoned about, and we can talk about what kind of world benefits best from certain political positions. Scott Alexander suggests that the set of tendencies we associate with the far Right , (a heavy focus on physical defense and self-sufficiency, careful gate-keeping and control over population, and a distrust of social services), makes the most sense in a dangerous environment, while tendencies we associate with the far-Left, (a heavy focus on equality, including trying to ensure care for the sick and poor), spreads in an environment that’s safe and resource-rich.
In Alexander’s terms, Right-wing values are for surviving in an unsafe environment, (specifically, one with war, disease, and widespread trickery), while left-wing values are for thriving in a generally-safe world, (where things are generally trustworthy and the marginal cost of risky gambles is lower). This form of Apocalypse myth will appeal to people with Right-wing values: they present a rough world where only people with Right-wing values are able to survive. By suggesting that those conditions emerge in the very near future, such as in the first three Mad Max films, they justify a survivalist impulse.
Zombie apocalypse stories are a refinement of this genre, made to appeal to specific, timely ideas. I don’t think that this is necessarily the result of the filmmaker’s ideology; instead, shifts in the political climate have changed what kind of media resonate. Rather than embracing the same kind of 50s family-based patriarchy that you’d see in early nuclear apocalypse movies, (as parodied in Blast from the Past), the new cozy catastrophe features a band of free agents. Repopulating the world is explicitly made out to be a bad idea. We see some of the seeds of this kind of narrative in the more subversive takes on nuclear apocalypse stories that were showing up around the time Night of the Living Dead came out. A Boy and His Dog seems like a particularly good case.
Zombies themselves vary wildly. Sometimes they hunt by smell and other times they hunt by hearing or sight. They exist on a spectrum from totally mindless automatons to merely distracted animals. Sometimes they are dead and sometimes they are merely ill. Sometimes they move slowly and other times they move like lightning. The cross-genre commonalities specifically construct an environment that favors current Right-wing values. (Read the rest at Modern Mythology.)