Can anyone explain me the end of "the planet of the apes"?!

Can anyone explain me the end of "the planet of the apes"?

I've watched this movie thousands of times and i still don't know what happens in the end. I'm talking about the version starring by Mark Wahlberg, where he goes back to washington from a planet where humans are the apes's slaves, yet when he gets there the lincoln memorial is not longer lincoln's but another ape's one. I've thought of it and i can't figure out what happened. what do you think?

It's hard to say what exactly happened but Mark Wahlberg didn't travel back in time but traveled forward in time to a futuristic Washington. In this future, the apes have taken over Earth and now control the human race. Throughout the whole movie, Wahlberg was actually in the present time but he was in another solar system where there was a planet overrun by apes. In the end, when he thought he was going back to Earth, he was in fact transported into the future where something happened and the apes somehow took over planet Earth. The cause of how the Apes suddenly overran the human race is not certain.

I hope that helps.