Genetic differences between the races can't exist because there hasn't been enough time for them to evolve in the 50,000 to 200,000 years since modern humans first emerged from Africa . The popularity of this argument is bizarre, since genetic differences between the races are written on the faces of the people you see every day. It's particularly amusing to hear paleontologist Stephen Jay Gould assert this since his one major contribution to science has been to document that evolution sometimes occurs at the speed of revolution. A classic example is the gene for lactose-tolerance. It was almost nonexistent until humans started milking cattle about 10,000 years ago.
Race is only skin deep .
Races can differ in any of the ways that families can differ from each other. Most variation is within racial groups, not between racial groups. Two members of the same race are likely to differ from each other more than the average member of their race differs from the average member of another race . No single human category can account for a majority of all the many ways humans differ from each other. Yup, that's true, too.