In the original (1968) Planet of the Apes movie the humans are depicted as if they can't speak any language. Is that plausible?
How can humans lose their ability to speak? One can see that humans have lost all their knowledge - science, technology, language, culture, etc. Even if they have lost their knowledge of language, wouldn't they pick up language/words from the Apes and imitate them?
Actually, they could speak. That was shown in Beneath the Planet of the Apes when Nova shouted out Taylor's name.
They had just been treated like animals, probably bred (when in captivity) for stupidity and obedience and had lost their knowledge of language.
As TangoOversway already pointed out, the humans in Planet of the Apes did have the capacity for speech (i.e. making noises with their mouths). This is illustrated by Nova shouting Taylor's name. However, it should be noted that a loss of the capacity for human language is quite plausible when you consider the phenomenon of feral children:
They often seem mentally impaired and have almost insurmountable trouble learning a human language. The impaired ability to learn language after having been isolated for so many years is often attributed to the existence of a critical period for language learning, and taken as evidence in favor of the critical period hypothesis.
So, if the apes isolated human children during the first few critical formative years of their life, it would be nearly impossible for them to subsequently acquire any significant degree of language. This would not be due to a lack of the ability to speak, since they would still have vocal cords, etc. It would be a result of underdevelopment of the cortical brain regions providing support for understanding and producing language. In other words, they would be able to make or mimic noises, but wouldn't really have much understanding at all of what those noises mean.
It's hard to say exactly why the humans in Planet of the Apes didn't speak much. Perhaps they had been so thoroughly conditioned by the fear of the repercussions for speaking (i.e. punishment by the apes) that they just never did. Or perhaps many or all of them were "feral" and incapable of language, with Nova being an exception in that she understood the concept of identifying individuals by spoken names. Either way, the loss of the capacity for human language is plausible given what we know from modern neuroscience.
For something like this to happen through evolution as at least inferred in the movies, the conditions would need to be right so that communication with each other becomes a trait that is adverse to survival. While some regression may be possible perhaps even likely though programs that reduce education requirements and our need to learn and provide for ourselves, I find it highly unlikely that we could ever get to a point where that continues enough for Homo-Sapiens to naturally evolved to that state.
However It could be possible for the apes to evolve and take control of the Human population. Then through selective breeding terminate those humans that are intellegent and those that are not are breed. Through restriction of calories and protien that would create a situation where those traits thrive as minimized protien would promote reduced brain growth. As our language center is a large part of our brain then it would make sense that its function would be reduced.
It also makes sense that if after this period of thousands of years some outliers would still have gene combinations that would allow for speech but with out a large base able to communicate it would be hard for a sophisitcated language to emerge on its own. So mimicry of the apes language is likely to be the result.
I remember from the first book that the shame of having committed the atrocity of a global thermonuclear war has made the survivors abandon all technology and speech - isn't mentioned in the films, as I recall.
If apes have evolved to the point of being a somewhat dominant species then humans would also have to have evolved to something else as well. It doesn't make sense that evolution happens for apes but not people.
Also Pierre Boulles' book was satire and not considered sci-fi so the script writers probably had to invent a lot without really explaining everything.
I had a cat who used to make sounds as if he was trying to make words - he used to do it for 30 minutes at a time and was very, very vocal. I used to talk to him to encourage it also since it was cute. :) He used to have an "F*** you" sound that always made me laugh - a very short and loud, "merw".
Look at the movie, Nell. Isolate a child like that and the child will probably not have any means to learn how to speak, or if they adapted over time after not really talking, then they would never really learn how or know it was normal.
No. It's a Hollywood movie. In the 'real' world humans dominate and the other great apes are an endangered family. Non-human apes cannot and never will speak because they lack human tongues and voice boxes. If non-human apes are still around in the future, and have developed human-like tongues and voice boxes, they will have evolved into new species and probably look nothing like their present day cousins. The same for humans: if we were to lose our human tongues and voice boxes in some far distant future, we would no longer be humans but some other strange looking hominids. However, I cannot envisage this ever happening as humans are social animals and cannot survive without a complex language to pass on information and knowledge.
