Do you ever think about how different you were 1 day ago, 1 month, 1 year ago? We are constantly in a state of change. Your personality is a result of, what you've eaten or drank, the temperature, people you interact with, every stimuli around affects our very being every second of every day. Its through this life experience that evolves us as human beings. We make mistakes, we learn from them, and naturally we become better, more efficient. Think about every skill you have ever learned in your life, you were never good at them initially but through many many iterations of doing the same task we eventually master what seemed to be impossible at first. This changing, learning, and ultimately growing is the theory of evolution at work in your everyday life.