Yes. I don't want to start a relaxer debate, so please bear with me:
My mother was one of those women who had GORGEOUS, thick reddish brown hair back in the 70's and 80's. In the early 90's, she was still a young woman, so it wasn't that her hair was thinning. Here's what I think happened: the changing ingredients in relaxers or box perms. I think the chemicals became harsher. Also, I think many women of the 60's, 70's and 80's [excluding public figures] pressed their hair instead of relaxed it. I think pressing is less stressful on the hair than relaxing. My mother, who STILL relaxes her hair, even agreed that she thinks relaxing has caused a lot of thinning in black women's hair as well...