Word geekery: Something I've always wondered:

How did the meaning of the English word "Nut" evolve from: "a hard, indehiscent, one-seeded fruit, as the chestnut or the acorn" to: "a foolish, silly, or eccentric person"?

Did the word somehow get filtered through the word "Squirelly"?

'Cause I can understand how "Boy, he's sure a squirrelly fellow, ain't he?" can mean "he's a foolish, silly person," because squirrels (from our p.o.v) seem to run every which way in a nervous, nonsensical fashion. And squirrels are associated with nuts.

Or is it that "nut" is also a slang term for "head?"

Anyway.

I'm wondering this because the other night, I found I'm a Nut, by Leroy Pullens (1966), on YouTube. And it's been running through my head ever since*:

[Chorus]
I'm a nut, I'm a nut
My life don't ever get in a rut, whoop-whoop-whoop-whoop
The head on my shoulders is sorta loose
And I ain't got the sense God gave a goose
Lord, I ain't crazy, but ...I'm a nut

Is is wetter under water, if you're there when it rains?
Is it shorter to New York, than it is by a plane?
Between myself and I, I wonder who's the dumber
Is it hotter down south, than it is in the summer?


*help me! -- If you dare, here's a vid:

http://www.youtube.com/watch?v=EYu7gnLo688. Most vids of this song are just slide shows of semi-related Google hits. But this one actually shows four women line dancing to this song, so it actually has a modicum of creativity and effort.