Hair by Sally Hershberger.

If any haircut has its roots firmly planted in the fertile fashion soil of rock ‘n’ roll, it’s the shag. Think back to the ’70s, picture Mick and Keith, Rod Stewart, Bowie…and there it is. Later, consider, the boys and their hair bands—K.I.S.S., Alice Cooper, Ozzy Osbourne; their shags were as “regulation’ as their skin-tight pants and sky-high boots.

Then the ladies got into it, putting a fashionable spin on the layered look. Jane Fonda kicked it all off in “Klute;” the cut went on to…