The notre dame style of polyphony, in which the tenor line was based on a pre existing chant melody and the upper voice moved freely (and more rapidly), was called:

This style of chanting is called organum. Organum is a form of music from medieval times that is based on an existing melody. It includes an added voice that helps enhance the harmony of the music. It is often seen in Gregorian chanting and is one of the earliest types of music.

Photography has changed its subject matter quite a lot over the past few years. in the 1800's, it was considered normal for families to have  post mortem photos of their loved ones, and now that would be completely unacceptable. i think that photographers have always pushed boundaries and have been eager to capture everything, it is just society that changes their boundaries.

Ibelieve the answer is the renaissance