As I said, perhaps there could be more efficient ways to make a brain. Evolution is unlikely to do it for us in any appreciable amount of time. Maybe direct genetic manipulation could, but that's a technique that would serve future generations.

The people with hydrocephalus, and people with brain damage who end up more or less functional, are benefitting from that brain plasticity that I was talking about. Different parts of the brain picking up the slack. Hydrocephalus is also often associated with behavioral and emotional problems, so it's not like a perfect compensation.

I'm not arguing that there is no possible alternative, only that, things stand now, artificial expansion of the brain is the most likely way increase human cognitive ability of existing humans.

If someone comes up with a way to make a human with 50x neuron density, I'm happy to be the experimental papa to that kid.