Other asians like phillipinos score significantly less (around 90).  It is difficult to explain how the environment, racial bias, etc. could explain these consistent differences which show up all across the world.  Rushton continues this line and says that there are other traits which differ between groups.  He dichotimizes it into 3 races to make a point.  He could as easily done it with 4, 5, 6 , 7 or infinite races.  As humans we need to categorize things because that is the only way we can make sense of the world.  Technically every organism in the world could in theory be it's own "race" since everyone differs slightly from the next.  No two creatures are exactly alike (for the most part).  Putting things into categories is arbitrary because every living thing is related to each other by differing degrees.  Fish, birds, mammals etc. all had a common ancestor and are all related to each other by varying degrees.  It is only in the human mind that there are clear demarcations between anything.  However, in the real world these differences are meaningful to us and categorization is necessary.