The History of The Beatles as told by their hair can be found at the always inventive FlowingData web site.
Can you guess which head belongs to which Beatle?
It’s remarkable how much the Beatles changed their looks in such a short period of time.
The History of The Beatles as told by their hair
Smart People I Know 
From left to right
John Lennon – He’s the only one that wears those kind of glasses
Paul McCartney – since he was the only clean shaven one in the 70s
George Harrison – by process of elimination
Ringo Star – because this has the smallest head.
Not only are you right, but your logic is impeccable.