Evolution of morality

Morality is like the rules for how people should act. Over time, people have thought about different ways of making these rules. As time passes, we learn from our mistakes and think of better ways to be good to each other. We learn that some things that were once OK (like slavery or not treating women fairly) are now wrong. We also learn that some actions that were thought of as wrong (like helping people who are not part of our group) are now seen as good.