Sure you have a big brain; it's the hallmark of Homo sapiens. But that doesn't mean that you've cornered the market on intelligence. Admittedly, it's difficult to say, since the very definition of the term is elusive. Depending on what we mean by intelligence, a certain aquatic mammal is not as smart as we thought (hint: rhymes with "caulpin") … and your rhododendron may be a photosynthesizing Einstein.
And what I.Q. means for A.I. We may be building our brilliant successors.