This was a period after the Stone Age characterized by the manufacture and use of bronze tools and weapons made by heating and combining and tin. etc, look at the image

Bronze Age

Explanation:

The Bronze Age is the second period in the Three-age system, after the Stone Age, and Before the Iron Age. As the name implies, the Bronze Age is a period in European and Near-Est history, in which the use of bronze became more common, representing an important technological advancement in the use of metallurgy for the cultures that achieved so, so much that those cultures that used bronze tended to be more successful and override those that did not know how to melt it and use.

answer; elasticity of the lungs decreases;