Does basic human nature change?

 An article in Daily Art caught my eye and I used one of the illustrations as my daily art post on the Off Topic section of Breaking News.

The article concerns the discovery of exotic paintings on the walls of buildings in Pompeii and explicit phalluses carved here and there.  Many of these paintings have been known since the 18th century but have been locked away in the  National Archeological Museum in Naples but the secret museum has now been opened sand all the erotiica is now visible.

Looking through the article with its illustrations I remembered all the other art works, many by the most famous artists, which display nudity and it occurred to me that human nature has remained basically the same for millennia; the most important  things were and still are: food, shelter and sex.

The paintings also made me wonder where is the line between erotica and porn. It's a line which has moved considerably over the centuries. If we look at paintings we can seen that somewhere in the middle of the 19th century the view of the nude changed from being polished, staged and confined to Adam and Eve, goddesses, Greek myth and the like to portrayals of real people with real bodies.

So my questions are:

Has basic human nature changed very much over the millennia?

Where is the line between erotica and porn?

An odd combination I will agree but the latter has been bothering me lately as I look at many paintings online and  many of them are of nude women. That we are beginning to rethink our attitude to these masterpieces (many of them are masterpieces of painting) is summed up by this painting, based on La Grande Odalisque by Jean Auguste Dominique Ingres, 1814.

This Style 10/6 (aka Richard Jones)