Taking the "different kind of intelligence" a step further, I'm thinking about the evolution of brain function. Humans are soft on the outside, vulnerable to damage. Early man developed shields, then armor, and metallurgy became an important science, figuring out how to melt and smelt combinations of metals to make them stronger or more pliable. Theories of alchemy emerged and people dreamed of changing lead into gold, and finally scientists discovered that each metal has its own atomic number, that being the number of protons and electrons in an atom.
An alien with a diamond-hard exoskeleton might have the same IQ as a human, but they don't give a rat's behind about metallurgy, so they never pursued it, thus, their brains evolved differently.
