Brain energy
The article on why humans can't get smarter does an adequate job of defining a problem, but is way too negative. If brains need more energy to get smarter, than the answer is to get them more energy--that's simply a biomedical problem of the sort we've solved many times before. I have no doubt some scientists are already saying, "oh yeah, we can too get smarter." Seems to me there should be a way to increase the oxygen-carring capacity of blood which would increase the energy nourishment of the brain. Or perhaps an external energy source could be attached to the skull in a hat that would feed micro-jolts of electrical energy into the brain via a few key electrodes. This brain problem is a relative limit, not an absolute one.
