I think it is all perspective. What you and others see as I decline in actual individual IQ's whatever that is, could be perceived as a number of things, including but not limited to more individual expressive freedom, and that much more knowledge abounding to make the individual look less knowledgeable and therefore less intelligent.
Culturally, up until a hundred years ago white people would do imitations of African-Americans, in a very patronizing manner, accentuating blissful ignorance, the culmination being the black-face performances of white vaudevillian artists, and radio shows such as Amos and Andy. Today we show the same thing with reality bites on Youtube. In fact, I see where the Census Bureau is just now stopping the use of the term Negro, which was a slaveholder term.
I am more than willing to go Downtown Toledo, and put together a video with UMC white folks, those that work the top level government and legal jobs, on basic civics that my kids need to know, and they would look stupider than shiit. (I know this because it wasn't that long ago that my seventeen year old and her class mates did it. There was a great story about an ex-mayor getting assaultive with a kid on a similar mission.)
I believe actual worldwide IQ rates are increasing because of additional nutritional advantages. I believe aspartame, high fructose corn syrup are working against us, but I think basically people are the same dumb shiits they have always been. I remember after basic training having a conversation with my dad and great uncle. They laughed at my questioning the intelligence of my fellow recruit. My basic had very naive folks from certain areas; my father who did his basic just before Pearl Harbor, talked about the number of recruits that could not read or write; my great uncle talked about the number of recruits that could not even speak English, and had no comprehension of those issues facing them (WWI era.) The stories were incredible!