Upvote:0
Some busts and statues were made when the person was alive, others were copied from these. So in some cases one can be reasonably certain that there is a close similarity with the original. I suppose this applies to all Roman emperors, for example. Probably to the busts of some famous Greeks, like Pericles, or Greek/Macedonian rulers of Egypt and other Hellenistic states. As a check we have coins with the portraits of many of those personages. Certain faces of antiquity are easily recognizable because of the multitude of depictions of the same person which have a lot of similarity.
Upvote:1
Ancient Egypt
I asked myself this question just the other day and done a little online searching.
According to the Museum of Fine Arts Boston, sculptures displaying true likeness were a rarety in Ancient Egypt.
Sculptures portraying true likenesses of people (rather than highly stylized portrayals) are rare in Ancient Egyptian art, both before and after the creation of Ankhhaf's bust.2
Ancient Egyptian bust, by Lthomas2
Greek and Roman
Overall, Roman portrait sculptures are claimed to be more reliable than their Greek or Egyptian counterparts, though admittedly, there is no source for this claim outside of Wikipedia.
Social and psychological aspect, wikipedia
Unlike the ancient Greek portraits that strived for idealization (the Greeks believed that a good man must be beautiful), Roman portrait sculpture was far more natural and is still considered one of the most realistic samples of the genre in the history of art.