Only a “purely evolutionary perspective” would fail to see that the primary reasons for the survival of old women are intelligence and culture. Some old women are useful; some are not. But intelligence causes most of them not to avoid stupid situations where they just get killed (the way an animal might). And cultural values, carefully nurtured by the old women themselves, cause their survival to be valued. Treat this sort of evolutionary biology the way you would treat grievance studies. Be polite.