Although people are better at making resources and can make enough for everyone now, many people still want to use some sort of hierarchy. Those people cling to the idea of race and that some races have certain behaviors and personalities that are less then other races. They try to group bad behaviors to one or more races to justify not treating everyone the same, so that their race can have more power, money or privileges. 
Not everyone sees physical difference as the most important difference among people. In many places cultural difference is more important in defining people. This is perhaps because people look very difference among each other within very little land area. For example, a group of people who think of themselves as one people could have a lot of physical difference, but are one group because they share the same culture. Since they vary physically within their group, they might see other physical differences as not that important. They might see others as different based on culture instead. 
The reason why there is biological difference among people today is that people adapted biologically and culturally to the different environments. Without such adaptions, all people would not have survived long enough to make anything we take for granted today. Biologically adaption was the only thing keeping us alive until our ancestors were capable of making clothes and tools to survive in the elements.
 One such adaption is skin color, or how much melanin is in one’s skin. Close to the equator there is more ultraviolet light, so skin needs more melanin and is thus darker to protect from sunburn and skin cancer. If one is far from the equator there is less ultraviolet light, which is needed to make vitamin D. So as a biological adaption, skin started to have less melanin and got lighter the farer from the equator one traveled. This adaption helped to absorb ultraviolet light better, so people could still make enough vitamin D. 
In my opinion, no matter how you try to group or classify people, there is no collection of people that is pure good or pure bad. I think that the things people are born with do not make a person one way or another. What makes a person have good behavior or bad is how that person is raised and what that person is taught when he or she is young.  You can’t just look at someone and know what kind of person he or she is, and I think most people are good no matter where they are born. I think people should get to know someone before thinking anything about that person, because personality and what kind of person someone chooses to be is more important then anything else.
