racial discrimination

A man from Nigeria was declined employment in the steel company in Belgium because of racial discrimination. A manager of this company said his dog bited people who were not white because the dog was racist. A man said he was barked by the dog when he arrived at the company. The manager said he declined his employment because there was danger his dog bited the man. The authorities regarded the manager as a racist and robbed him of right of employment. But, the man said he had experienced such things many times in Belgium. I can't believe occurrences like this in Japan. Why people discriminate because of only the difference of skin's color? What color is the best? I think there is no answer and I also think there can't be answer.