An average brain weight by ethnicity/nation

True. There are people who have much of their brain as a void due to some sort of congenital issue. They aren't less intelligent than others.

They are often less intelligent. The loss of brain tissue is not without significance, for example, in old age we simply become stupider.

Says who?

What about all the experiences made?

The experience is like driving to work. You drive mindlessly, always on the same road. This is what the cerebellum does, not the brain. The brain is used to solve new problems.

What problmes are you solving, kaffir?

I only advise, that's my job