Lots of people are walking around with brain damage. We seem to be able to compensate for quite a bit of it very well, assuming each incident of damage is small and they're spaced out enough.

If the damage associated with age concerns you, you might want to start asking people if they engage in certain very physical sports with high concussion rates.

A new meaning for the "Never trust anyone over 30" slogan...

Just as a heads up, Cato Unbound's latest issue is on IQ. The kickoff is from James Flynn.

Well, if a quarter of vaginally-delivered babies suffer detectable brain bleeds, then I'm going to adjust my view of what a normal brain is, if only for personal comfort as I reach my middle thirties.

Related topic from ScienceDaily:

Several genes with strong associations to schizophrenia have evolved rapidly due to selection during human evolution, according to new research.
...
It also provides genetic evidence consistent with the long-standing theory that schizophrenia represents, in part, a maladaptive by-product of adaptive changes during human evolution - possibly to do with aspects of creativity and human cognition.

I like this theory because it's the same one I conjectured-up years ago based on a loose analogy between the rapid evolutionary development of the human brain, and software development; i.e., if you release it "too early" it'll have more bugs, but if you spend the time fixing the glitches before release, the (buggy) competition will swamp you.