Summary

• Humanity lost ability to speak due to nuclear war, radiation exposure, and generations of demoralization in Planet of the Apes lore.
• The Simian Flu in prequels caused loss of speech in humans, furthering apes' dominion due to mankind's arrogance.
• New movie Kingdom of the Planet of the Apes introduces Mae as a human who retains speech and intelligence, hinting at hope for humans.

Between the original classic and the modern prequel movies, the truth behind why humans can't speak in Planet of the Apes is revealed. The classic 1968 film plunged viewers into a nightmarish world in which evolution had been turned upside down, and apes ruled a post-apocalyptic Earth while humans had been reduced to little more than primate-level animals subject to hunting, scientific experimentation, and general brutality. In the first two original films, the remnants of humanity are shown to be incapable of speech or any kind of sophisticated communication.

The humans' inability to talk further reverses the role of the two species with humans turned into grunting beasts while the apes are intelligent vocal creatures. It is an aspect of humanity that plays a big role in the Planet of the Apes franchise. The iconic moment from the original movie of Charlton Heston's Taylor shouting "Take your stinking paws off me, you damned dirty ape!" shows the surprise the apes have in coming across a talking human. However, the reasoning behind the loss of speech differs from the original movie to the new prequels.

How The Original Planet Of The Apes Movies Explains Why Humans Can't Speak

Humanity's Downfall After Nuclear War Led To Them Losing Their Ability To Speak

Discovering the secrets behind humanity's inability to speak in the original Planet of the Apes films involves taking a deep dive into the series' lore. By looking to sources including spinoffs, informational texts, and even the original novel that inspired the movie, a more complete picture of what happened to humankind begins to reveal itself. In the end, the true reason for humans losing their voices comes down to three factors: mutation, subjugation, and demoralization.

As revealed in the finale of the original Planet of the Apes, humanity's end came at their own hands via atomic war. This war, which was fleshed out in multiple comics and short stories, saw much of Earth devastated beyond recognition. Only small pockets of greenery continued to exist, and it was within these pockets that apes began to build a new civilization with the aid of human labor.

[E]xposure to the radiation of the planet's contaminated deserts, or "Forbidden Zones," led to their vocal cords degenerating over time.

As explained in the ending in Battle for the Planet of the Apes, the chimp that led his people to freedom, Caesar, pushed for equality among humans and apes. Unfortunately, this equality was not to be; over the succeeding centuries, the relationship between the two species continued to degrade. Humans went from mere laborers to slaves and from slaves to pets. As explained in the Apes expanded universe, generations of demoralization resulted in less intelligence and willpower among humans.

In addition to this, exposure to the radiation of the planet's contaminated deserts, or "Forbidden Zones," led to their vocal cords degenerating over time. With each new generation, fewer and fewer humans could speak. Eventually, strict religious practices on the part of the apes forced the humans out into the wild, where they further devolved and became more animal-like.

What The Original Novel Reveals About Humanity's Loss Of Speech

The Main Character Of The Original Novel Met A Similar Fate

Although none of this drama has ever been played out onscreen in any of the Planet of the Apes movies, a haunting example of this kind of mental devolution can be found in the book that launched the franchise. French novelist Pierre Boulle's satirical sci-fi classic La Planète des singes (Monkey Planet) was the basis for the 1968 film and featured three astronauts venturing to an alien world populated by intelligent simians.

One of the novel's characters is Professor Antelle, a brilliant scientist and leader of the expedition. After the novel's main character, Ulysse, was captured by the apes, Antelle disappeared, only to reappear near the end of the novel living in a cage, his brilliance stripped away. Now living like an animal, the once-genius man was now little more than a beast. The same disturbing principle, albeit on a planet-wide scale, ultimately robbed the humans in the Planet of the Apes film of their voices.

How The Prequel Movies Address Human's Being Unable To Speak

The Deadly Flu Causes The Humans' Loss Of Speech

The recent Planet of the Apes prequel series that began with 2011's Rise of the Planet of the Apes did offer an explanation for humans being unable to speak: the Simian Flu. While a man-made drug gave apes high intelligence, it also proved to be deadly for many humans with the end of Rise of the Planet of the Apes showing its spread throughout the world, which led to apes becoming the most dominant species on the planet.

Dawn of the Planet of the Apes revealed that the small population of humanity that was left were immune to the disease and attempted to rebuild a semblance of society. However, War for the Planet of the Apes reveals that the disease mutated, further affecting many of the remaining humans and robbing them of their ability to speak. Regardless of the reasoning, both versions of Planet of the Apes come to the same conclusion, that it was humanity's arrogant ambition that led to their downfall and to be replaced by apes.

Humans Can Actually Talk In Kingdom Of The Planet Of The Apes

The Character Of Mae Presents A New Future For Humans

Kingdom of the Planet of the Apes is the latest movie in the franchise and continues to explore the idea of humanity being unable to speak in this new world. The story takes place "many generations" after Caesar's death while focusing on a new group of ape characters. However, it also introduced Mae as the main human character in Kingdom of the Planet of the Apes. Though she initially seems like a feral human, she eventually reveals to the apes Noa and Raka that she can speak and is intelligent.

Mae reveals that there are pockets of humanity left that are not affected by the newly evolved disease and have not lost their speech or intelligence. It is also revealed that some of the apes use these humans to teach them about their ways and to read. On top of that, it is revealed that the remaining humans have found a way to communicate with each other using satellites, suggesting that there is hope for the human race in this version of the franchise.