Why are all races biologically and psychologically equal?

Humans today do not have several biological groups called “races.” However, race is real and it affects all of us. What we call “race” are social categories. They play a role in our life and history. But all races are biologically and psychologically equivalent. Societies construct racial classifications not as units of biology, but as ways to bring together groups of people with different historical, linguistic, ethnic, religious, or other origins. These categories are not static, they change over time as societies grow and diversify and change their social, political and historical courses.