Evolutionarily speaking, neither a failure to make up your mind nor a proclivity to often change your mind would be very effective as a survival strategy. If you are living out on the plains or in the jungles, what you have been eating for the last several years is probably still good to eat, and what you have been avoiding is probably still best left avoided. The animals your parents avoided are probably still best left alone, and the animals your parents hunted are probably still your best bet. We learn new things by relating them to what we already know or think we know. Doing something different from what we have always done carries a risk.