Has mankind really evolved more empathetic? Well, slavery still exists. The west has totally become more empathetic for a variety of reasons, like guilt, and human rights movements.

You can argue that this empathy has existed for a long time. In the 1500s, Charles V outlawed slavery in his new world colonies against the natives. The Pope also outlawed slavery of the natives of the Americas, and of all people anywhere.

Slavery in the Americas was awful by all accounts. It was referred to as "chattel" slavery, where slaves are treated like property. Other forms of slavery that previously existed weren't quite as awful. Slaves in the past were at times elite military forces, educators, and had other prominent roles. Several cultures dating back to ancient times had outlines for treating slaves humanely, such as the Sassanid Persians.

The empathy has always existed.