"Evolution" is emblazoned across the publicity for the rebooted Planet of the Apes prequels, but is that label justified by their plots? One challenge for screenwriter Mark Bomback was to show why the apes needed to develop the ability to speak. It has been theorised that speech evolved because of the survival benefits of imparting information to large numbers of individuals at once. When the former San Francisco mayor Dreyfus (played by Gary Oldman) addresses a crowd of human survivors we see this benefit come into play, but we also see it when the chimpanzee Caesar holds court in his ape community. Wars can only be won or lives defended if those in the ranks are united through shared information.

Of course, humans and chimpanzees have distinctive anatomies for vocalisation, which presents further challenges. Chimps have a vocal air sac, for example, but humans don't. When I interviewed Andy Serkis last week, I asked him whether he was coached to get the correct breathiness? "No, I instinctively arrived at the voice, Caesar's urgency to express his thought, plus the expulsion of air through the larynx created the voice. If the emotion behind the word was anger or frustration the words were physically easier to produce. But if it was a reflective observation those words were harder to achieve."

In the latter part of Dawn, Caesar becomes increasingly philosophical and his self-reflection causes him sadness. When I tell Serkis that Keri Russell's line to Caesar, "Try not to speak", made me want to applaud, he laughs, "Yes, it's very smart dialogue."

Another problem with portraying language in the film is that different ape species and different individuals will have different capacities for speech. "The biggest fear for me was that we all start fluently talking and we fail to show the steps in the acquisition of language," said Serkis. "The premise was the apes all had their individual vocalisations and Caesar taught sign language to some of them. Some apes have had the intelligence drug coursing through their veins longer than others and are more advanced. We figured the older apes wouldn't be able to learn sign language as easily as the younger apes, as it is with humans learning [language].

"This phenomenon is seen in intelligence studies with captive female apes that are suckling an infant. The mother ape is the pupil but unbeknownst to the researchers unintentional hothousing of the infant takes place, eventually resulting in an exceptionally smart adult ape. Chimpanzee Ai in Japan and bonobo Kanzi is the US are both examples of this.

"We went through the whole script and had American sign language (ASL) for every single line of dialogue, then we stripped it back. We needed the apes to develop a mix of facial expression, gesture and the spoken word. As the apes respond to the effects of the drug the overall ape communication is pushed from reality."

With Dawn on cinema screens, Serkis plans to continue mining this rich seam of close-to-life animal performances made possible by motion-capture technology. Orwell's Animal Farm and Kipling's Jungle Book are on the slate at Imaginarium, his motion-capture studio at Elstree. "I think performance capture has applications in demonstrating different species through serious observation and via the way the human body is re-targeted into the character map. We can assign different parts of an actor's body to the animal's joints, so you are driving them and eventually you can calibrate it, it's very authentic."

What is he working on right now? "A project about Neanderthals. It's possible to digitally recreate a Neanderthal from the genome sequences, so we are doing an experiment to show how motion capture can bring extinct species to life."

All the great ape species that inspired Pierre Boulle to write the original Planet of the Apes novel 52 years ago are now threatened with extinction. When they no longer exist in the wild possibly the only way future generations of children will see new footage of apes will be via actors and motion capture. "Motion capture does have an educational role," said Serkis. "The bushmeat trade and loss of habitat is tragic."

In Dawn, the ape Utopia started well with "Ape shall not kill ape" as its guiding principle. But with war brewing, can such ideals survive? They haven't fared well among humans. Personality tests on chimps reveal that they share all our traits except for "openness to experience" and "neuroticism" (though there is some debate about the latter). Caesar appears to have developed openness to experience, but what if he or the other apes were to become neurotic?

No ape in his or her right mind would want those around to develop the pathological disorders of narcissism, excessive greed, sadism and callousness. People with these personality traits lack empathy, but it could be argued that others on the same spectrum have their uses in an advanced society.

This type of mind is described as systemising. Those highly skilled, or extreme, in systemising may be on the autistic spectrum, with neurosis and zero empathy at its extreme. Represented in all walks of life they tend to cluster in professions that follow rule-based repetitive systems, as found in academia, languages, law, politics, technology, banking and engineering.

If Caesar wants to build a society based on the human model, this brain type will need to be represented in the ape population. Can apes learn from the mistakes of humans? My recommendation would be for Caesar to emulate the way of the bonobo, promote the female of the species and forgo nuclear fission. In human society, there is an empathy gender divide, with females tending to exhibit higher levels of empathy. Among other apes, the bonobo is a matriarchal ape and far less aggressive than patriarchal chimps.

In spite of the chimp's increasing sophistication, the climactic, vast and trunkless Statue of Liberty, buried in sand and defining human civilisation as a forgotten colossal wreck, remains many winters away. Happily, several more films will be needed to get us there.

I pushed Serkis to comment on the next film's plot, but he gave little away, apart from confirming that Caesar will be facing many more dilemmas.