The New York Times had an article this week about how smart fruit flies have shorter lives than their more Bevis and Butthead counterparts (heh heh). (My age showing any?)
Absolutely. Intelligence doesn't give much of an evolutionary advantage.
Proof 1: "Smarter people" (defined in terms of IQ, troubling, but we're not going there for this post) have fewer babies in the modern world. I can't find the cites right now; I'll keep looking. But, basically, you may recall that there was quite the brouhaha awhile back stating that birth order affected IQ--successively younger children were less intelligent than their earlier-born siblings. However, it turned out that the difference was not in birth order, but rather in the intelligence of the entire family; to wit, larger families were less intelligent than smaller ones. For the record, I'm the oldest of seven.
Proof 2: Ashkenazi Jews, who actually appear to be smarter (again, defined in terms of IQ) than the rest of us, seem to owe that intelligence to mutations that also cause them to have extremely higher rates (59% of the population heterozygous for at least one) of various troubling diseases, specifically, the sphingolipd storage diseases Tay-Sachs, Gaucher, Niemann-Pick, and mucolipidosis type IV. (Much more info here.)
Proof 3: There's lots of variability in IQ in human populations; traits that are beneficial propagate pretty evenly. Again, can't find cite--will keep looking. But this should be pretty obvious.
So, Oh Brave New World--American Idol, and whatever that show is that make people eat insects for, uh, cash prizes? here I come!