It astonishes me that people can claim with a straight face that it is not. I suspect it is sour grapes or something?
If intelligence isn't measurable, then you would agree that the average frog cannot be reliably distinguished from the average human in terms of intelligence?
Ok, so lets move on from that, and don't give me some painful story about how there are different kinds of intelligence and frogs are 'smarter about eating bugs' or something, please?
Maybe with the benefit of the doubt, you are trying to say that human's are genetically not very diverse, and so you can't find significant differences in intelligence. To that I would say you are certainly not claiming this in good faith, and you have some quasi-political reason to deny something that is obviously true to anyone who has interacted with more than 3 people. (and we can skip the lecture along the lines of 'you can't trust what is obvious and have to pretend that all your beliefs are properly cited or they are invalid')