The Greco-Roman period refers to ancient Greek and Roman rule. During this time, nude sculptures were very popular; the Greeks were especially intrigued with the beauty of the human form, and artists welcomed the opportunity to depict the human body in movement.
For instance, the Parthenon sculptures included figures representing priests, soldiers, maidens, and nobles (all in various stages of movement). Both Greeks and Romans reveled in depicting gods and goddesses in all their physical perfection. Nude sculptures like the kouroi (nude male youths) and kore (clothed female figures) were extremely popular in the Greco-Roman world. The initial kouroi statues were rigid and sterile in terms of "flow." Later, Greek sculptors resorted to using marble to depict ever more realistic figures. With marble, a sculptor could more accurately depict the flow of a garment or the intricate expression on the face of a figure.
Nevertheless, Greek and Roman sculptors concentrated mainly on depicting the beauty of the male and female form. On the other hand, sculptors and painters during the Middle Ages depicted the human body as a visual metaphor for sin or righteousness. For example, in the 15th century Martyrdom of Apollonia, Saint Apollonia was depicted as a white figure of sanctified purity, while her attackers were depicted with darker-hued skin tones. Basically, the darker skin demonstrated the depravity of the attackers' human natures.
During the Middle Ages, relics consisting of body parts of saints were revered by many in the Catholic Church. Each body part became a religious statement of sorts; the clergy profited from the trade in sacred relics and the church coffers were filled with pilgrim cash. Unlike the Greco-Roman preoccupation with physical beauty, the depiction of the human body was largely religious or political in nature during the Middle Ages.
Nudes were not unusual during the Middle Ages, but they were always portrayed as part of a religious statement. For example, nudes of Eve often depicted her as an ambivalent figure. She was both portrayed as beautiful and dangerous. As the crown of all creation, Eve was a thing of beauty; however, as the one who first partook of the forbidden fruit, she was also a dangerous figure. Thus, the message was this: as a danger to humankind, women needed to be simultaneously tamed and protected; indeed, they were constantly subjected to masculine authority.
The human body was also depicted in other ways during the Middle Ages. While the male body was used to depict the power of the state or government, female figures were used to portray the citizenry. The female body was always depicted in a posture of subservience during the Middle Ages (in both religious or secular art).
So, while the Greco-Roman artists concentrated on depicting accurate proportions and physical perfection (art for art's sake), artists during the Middle Ages were largely consumed with using the human body to make religious or political statements.