Socioeconomic class is basically another culture in terms of influence. These two terms can be used interchangeably as they both have the same effect on the perception of beauty. Your question is something I can answer. It differs across cultures because the minds interpretation of beauty involves external experiences. That is why.
As for your comment about universal rules. Well that's also easy. Universal rules involve symmetry and youth. Possibly more, but those are some of the biggest rules of beauty extend past "culture" so we know it's part of biology.
>Could you create such a rule which is consistent over time?
The answer is no. None of these rules are created by anyone or anything.
>Do you think those rules would have been consistent by era, or would they have varied in times of famine versus times of surplus, and could you create anything consistent across civilization? How about by geographic areas which shaped the city states which served as centers of power in those civilizations, IE how feminine beauty may exist on the steppe vs on the coast, or in the mountains?
These rules vary by culture, culture varies by environmental circumstance and genetics. You're getting into a redundancy here. I think you misinterpreted my post. I DID not say that culture does not influence beauty. Quite the opposite. I said Culture DOES influence someones perception of beauty. Read my post, it is there. However and this is a big "However" you do not have a choice in the matter. You do not choose your culture and you do not choose the ideals that are imprinted onto your brain by that culture. Once imprinted on your brain you cannot change it. If the culture values skinny bombshell models then that ideal will be seared into your brain. There are variations and anomalies but overall it is generally consistent.
It's the same way that a baby bird imprints on the first thing it sees as it's mother. It does not have a choice. Your brain is evolved to assimilate itself into it's environment and culture without conscious choice from you.
That being said outside of this as I previously mentioned there are beauty standards that are universal that are not created by culture, two examples already mentioned are symmetry and youth (for women). We know this because surveys show that these ideals do not shift when observing different cultures. Additionally, quite obviously: men are generally attracted to women and women are generally attracted to men, there is some genetic influence making this opposite sex attraction preference generally consistent across all cultures.
Do not discount these universal rules. They are powerful biological instincts and overall... When in conflict they usually override cultural imprints of beauty.
>Speaking about cold hard truth is challenging when working from a basis of archaeogenetic ignorance. You risk overestimating how universal your priors are.
Except this statement doesn't make sense. If everything I say is logically correct and everything you say has issues with correctness, then who's the ignorant one?