How does Serkis’ version differ from the original one? What mistake did Serkis find in the original version?

W: Welcome to our show, Andy. You know the audience is interested in comparing the two versions of King Kong. The original King Kong didn’t exactly take a scientific approach to portraying gorilla behavior. Why go to such lengths to get it right this time?
M: I don’t think the film makers in 1933 were out to understand gorillas. In a sense, Kong was just a monster to them. The difference is that our film is not really a monster movie. Early on we decided we did not want a Disney-filed-humanized version of Kong. My job as an actor was to observe as much as I could and bring those observations to the character.
W: What did the original get wrong?
M: In the 1933 version, Kong walks around on two feet beating his chest with clenched fists. Actually, gorillas walk on their knuckles and feet and cup their hands to beat their chests when they are angry. Also, in the original, Kong goes around chewing people’s heads off. Now we know that gorillas’ diet is vegetation.
W: So the new Kong is a vegan wimp.
M: Not quite. Gorillas are still wild creatures. That’s made very clear when you observe them in nature. They charge and perform other displays that are terrifying by design. But they don’t attack unless they feel threatened.
W: What makes gorilla watching such a profound experience?
M: There is something about seeing this totally peaceful society that has its own order and seems to work perfectly were it not for interference from humans. It’s like sitting around with a chilled-out load of hippies. They’ll just have something to eat and then crash out for a bit and then have a little walk. You’re supposed to keep a seven meter exclusion zone so that they don’t catch diseases. But gorillas go where they want, so they go all around you. It’s absolutely thrilling.