I dunno. I was pretty cognizant of most of the A-list stars that were big when I was born or in the generation before me-- Dean Martin, Bob Hope, Fred Astaire, etc. I would think, by the same token, if I was born in 1979, by the time I was 35, I would know definitely recognize most of these. In fact, I think by the time you reach 35, most of these would just be basic knowledge to anyone who's interest in current culture is more than just for the flavor of the day. If not interested, fine, but its not because their spotlight was short. Its because you obviously don't pay much attention to stuff that came before the Biebers. A lot of people do, and always will.