In many ways art is evolutionary: most artists build upon and extend the cultural and artistic legacy they’ve inherited. But what the Ancient Greeks achieved was revolutionary not evolutionary: they created a new art form distinct from everything they’d seen before; one that transcended their specific culture to influence many, many generations of future artists.
The Romans took the nude directly from the Greeks, but the form died out with the Roman Empire. It took a thousand or so years for the form to re-emerge: re-discovered, re-interpreted and re-vitalised by Renaissance artists. And these two highly significant eras were a fundamental force behind much of 19th and early 20th Century Western nude art. For example, the nudes outside the New York Public Library can clearly trace their heritage to Ancient Greece via Renaissance Italy (but no further than Ancient Greece).
By contrast, the many representations of partial or complete nudity and sexuality created in other times and places throughout history have generally been culture-specific. Once the specific culture has disappeared the artistic form has died too.
My understanding is that it’s slightly different with Oriental (e.g. Chinese and Japanese) art, in that the nude as a subject didn’t appear until relatively recently – perhaps as a Western influence. In traditional Oriental art, naked people were depicted as part of scenes of everyday life but not as subjects in their own right. If I’m wrong then I’d be more than happy for someone to educate me about this.
(Vaughn: as an aside, if the “horndog to robot” continuum had been my original idea I would probably have used different words too. But it wasn’t so I didn’t.)