Over the long haul, I'd say that bassists have a substantially higher aggregate IQ than other instrument players.
I know, I know...it's hard to believe with the noisy gristleheads that seem to take up most of TB's bandwidth, but I really think it's true overall and nobody I know watches people harder than I do.
They have a lot of stuff that descends from that, like thinking more and saying less, more serious, less spontaneous, geekery of all varieties, alienation from the rest of the group, personal obsessions that drive everyone nuts, zero charisma, etc.
Exceptions everywhere, of course, but we're talking tendencies.
Hey, you ever do this?:
You look at bunches of those sad little promo pictures of unsigned, struggling bands and ask, "which member doesn't fit?"
Y'know, there's the one guy who really doesn't belong there? Everybody looks like they're in the band and reading the same script...except for...him. The guy who gets kicked out of the band if they ever get real management and a label's artist-development coach?
About 80% of the time it's the bass player.
No, I'm not kidding. Up to that point he's been invaluable because he's the only consistently reliable guy in the band, but when the band gets serious, it's not enough.