A pretty broad question, but I get the impression most of us are trying to in some way. A better question might be, in what ways or under what conditions can/do people change for the better?
Studies and sources welcome
In some areas I think yes and others no. I also think as people age and learn from life and past experiences that may cause some change. But a person has to want to change what they or others may dislike about them. Opening minds and educating oneself are other ways people can possibly change in my humble opinion. Sadly, people can also change for the worse and not the better with tramatic life experiences.