Race doesn't exist in human biology. Genetically a caucasian could be closer to an aborigine than another caucasian, what we perceive as race are relatively unimportant and tiny parts of our genetic makeup.

However, race exists as a signifier in social studies, because people experience the world and are treated differently when they have different race-perception. For example black men driving expensive cars will be pulled over more frequently. Hence race exists as a social concept because people treat it like it exists in more than just that.