Gorillas are interesting because they actually possess the necessary vocal cords for language, but more recent study using the whole Koko thing, have proven they don't possess the corresponding language centre in the brain. It's like they are waiting to evolve.

More accurately the vocal cords evolved much earlier in evolutionary history for some other, unknown, purpose and were "repurposed" later on for speech when we evolved the language centre in the brain, which tends to happen a lot in evolution.