>>81697659 (OP)Young people haven't lived a long time, and thus haven't really experienced changes, so, from their perspective, a lot of things are "static". This means that, among other things, they see age groups as something permanent, basically different species. Young people are always young, adults are always adults, and the elderly are always elderly. Logically, they know that this isn't how things are, but their lack of experience means that this is how they subconsciously perceive reality.