There's an interesting mini-article here tracing the line "look at those cavemen go" to an old comic strip called Alley Oop. A commenter on that site added a tidbit that was incorporated into the article:
In reply to:
My mum's first boyfriend was a certain David Jones (a fact I've dined out on for years), circa 1964-5 or so. I can confirm that he was a comics fan, particularly the new wave of American comics that were starting to filter through - certainly Fantastic Four. He showed my mum the Galactus saga, which got her hooked. She, in turn, got me interested in comics. So, in a roundabout way, you could say that David Bowie is responsible for getting me into comics...
This stuff geeks me out. By the way, I've talked before about Bowie being a big fan of Watchmen. I wonder if he keeps up with this stuff at all.