Very simple, the ancient Greek culture embraced their sexuality and idealized the human form in their artwork. Throughout the ages, a muscular male form was desireable because it exudes strength, while a voluptuous female form was desirable as it exuded fertility.
The Christians however, chided sexuality and preached repressing natural urges. Thus, all male and females are, for the most part, depicted in heavy clothing and asexual body features, typically just enough to distinguish the sexes.
It is highly unlikely the actual appearance of the ancient greek and ancient christians were different, it was simply the ideals favored by the cultures.
Spartacus Blood and Sand - friggin awesome show.
