Serkis is a jungle VIP

You've played an ape before in King Kong, but Kong was a very different beast. How do you get inside the mind of a chimpanzee?

You just approach it from an acting point of view. Caesar and King Kong couldn't be further apart in terms of character. Kong was this psychotic old hobo who was, every day, trying to survive and never had any form of connection with any other living being until he met Ann Darrow. At that point his life was transformed and he began to feel things again.

With Caesar, the challenge is playing not only a chimpanzee, but also one who has been subjected to this drug that has altered his intelligence and made him super smart. In the early stages - because I play him at every stage from an infant to a revolutionary leader - it was about anthropomorphising this chimpanzee. He's like a gifted child. He's a 15-year-old child in a four-year-old's body.

Did you base him on research you'd done on real chimps?

I based him on a real chimpanzee called Oliver who, in the 70s, was known as a "humanzee." He was the subject of a lot of experiments because he was believed to be the progeny of a human and a chimpanzee. He's an extraordinary ape because he's bipedal. He totally related to humans and associated himself with human beings, and he was never in the company of other apes.

So I was playing this Frankenstein's monster who thinks of himself living happily with James Franco's character Will and his father, played by John Lithgow, in this strange nuclear family until he reaches an age of self-awareness. An event happens where they can't keep him at home anymore and he gets chucked into this sanctuary.

It's almost as if he's suddenly surrounded by all these strange creatures who look like him, but behave in this completely different way. There's no cultural interface between them because he's been brought up as a human being.

It was a very, very interesting character. And this is what performance capture, at its best, does, is that it gives you a skin that you think you recognise, but actually I wasn't just doing ape movements, I was playing this very confused, conflicted character within that.

It's the tension, really, between the manifestation on screen and the tension going on inside that hopefully will make it an interesting, layered character.

Has performance capture technology advanced much since you played Gollum?

Absolutely. I've also established such a strong working relationship with Weta Digital. I've now been working with them for 10 years. Joe Letteri, who's the visual effects supervisor at Weta, is just pushing the envelope every single time. And so are the motion capture team, which is lead by Dejan Momcilovic who's the world's best performance capture supervisor.

At the core of it, the thing is they have always understood that it's all about character and story and that the technology serves that.

I don't think there's any other visual effects studio in the world that really gets it as much as Weta does. But also, working with director Rupert Wyatt was great.

There were a couple of very important things that happened on Rise that hadn't happened up until this point.

One is that we were shooting on live action sets, so all the performance capture was done in one hit.

It wasn't the case, as it was with Lord of the Rings and King Kong, that I would be shooting on set and then I'd have to go and recreate it all on the motion capture stage.

This was all shot in the moment, and so all the stimulation, all of the communication between James Franco, Rupert and myself on set was very instant. Because it's all happening in reality, it has that level of truth that you have to try and manufacture on a motion capture stage.

Is performance capture better accepted by other actors these days? Wasn't it true that on LOTR that some of the other actors were rather bemused by what you were doing?

Absolutely, and I think it is becoming more understood. There really was life before and after Avatar, because it really took people like James Cameron and Jon Landau to say, "Look, these are actors' performances here. They are serving the story as an actor would do." These aren't animated characters - you wouldn't be able to achieve the level of emotional connection.

Drama is what happens between two actors; not what one person is giving off. You can't fake that. I think there still is a bit of a lack of understanding from the acting community. But I just don't see any difference whatsoever and I never have done. I can play Ian Dury or Caesar and I don't think there's anything weird about the latter - it's just another character.

James Franco, to his credit, it took him about half an hour to get over it, but once you're looking into the eyes of an actor who's in character, the rest of it is irrelevant. And he totally got into it and believed in the scenario and the relationship and it just worked.

I loved working with him; I just thought he was amazing.

He seems to have a unique perspective on the world.

I think he's a real outsider, James. And he's so intelligent as well. He's going off to Yale to do a Masters in English or something like that. He's a very, very bright man, and very deep thinking.

He's multitalented. He's an artist, a poet, and an actor. I think people underestimate him and what he's about. He's got a lot going on. He's very interesting and eclectic.

This film fits into the incredible history of the Planet of the Apes franchise, but do you think the fact it's set in the modern day will make it feel slightly different from what's come before?

For the vast majority of the younger audience, they will not have heard of Planet of the Apes. You're looking at a totally fresh audience.

I've shown the trailer to my kids, and they were mesmerised by it. It is this very powerful cautionary tale, in the same way that the sensibility of the 1968 Charlton Heston film dealt with issues of prejudice and racism and oppression and so on.

This is very much about the rights of one species over another and supremacy and a kind of arrogance, really. The arrogance humanity has that the planet is there for the plundering.

Hopefully we'll realise that the planet's going to be here forever and we're not. It's dealing with those sorts of questions and it is a fable, really, even though it's set in the modern day. I think it will really resonate to a younger audience.

For older audience members who are fans of the original Planet of the Apes movies, I think it equally works, because it has that sensibility of an older science fiction film.

I once said that it didn't feel like a visual effects film. And it's full of visual effects, obviously, but what I meant by that was that it actually feels more akin to Close Encounters of the Third Kind and the early Planet of the Apes movies, where the level of believability is very high. You don't think, "Gosh, I wonder how they did that?" You're really drawn in by the power of the story.

A lot of it is actually quite domestic. It's about very direct personal relationships as opposed to concepts. And it's about animal rights as much as anything.

Rupert Wyatt has talked about this film as being something of a prelude to war - have you had conversations about where this might go in film two?

Between us we've had conversations. You can't help but think about where it might go.

If there is a next film, it will be incredibly fertile territory, really - the whole formation of a society, what Caesar might retain of humanity from his experience of being brought up by human beings. Whether it's all bad or whether only some of it's bad.

In every species there'll be aggressors and I imagine it will reflect human society in that way. That's what's interesting; whatever species takes over the planet, they're going to be facing the same problems we are.