Final answer:
Ancient Greek sculptures were typically made from bronze, but most surviving examples are Roman marble copies. While bronze was frequently melted down, Roman replicas reflect the Greeks' artistic achievements. The change of material from bronze to marble led to differences in the sculptures' support structures and artistic presentation.
Step-by-step explanation:
The original sculptures created by the ancient Greeks were usually made from an alloy called bronze, composed of copper and tin. The marble copies that survive today are predominantly Roman recreations of these original bronze works. Due to the practical and commercial value of bronze, many of the Greek sculptures were melted down over time to repurpose the material, notably into weapons.
The Romans greatly admired Greek art and collected marble replicas, considering them a symbol of status and erudition. As such, our understanding of Greek sculpture is largely based on these Roman copies. The transition from bronze to marble required additional structural support in the sculptures, due to the different physical properties of marble compared to bronze, often resulting in the use of cleverly designed support elements like struts disguised as natural forms within the sculptures.
It is important to note the artistic differences that emerged due to the material change. Bronze, being lighter and stronger, allowed for dynamic poses that marble could not so easily support. The scarcity of surviving Greek bronzes means that much of what we know comes from these later Roman marble interpretations, providing insight into ancient Greek aesthetics albeit through a Romanised lens.