The so-called races that humans have been grouped into are cultural 
constructs and can not be reliably used to distinguish different 
ethnographic and/or cultural groups and definitely cannot be used to 
separate people into distinct biological groups.  Variations in melanin 
is notoriously variable throughout the world - not specific people of 
African descent.  Anyone that believes racial groupings are valid is a 
racist.  Sam Clemens was a racist, but as he got older the differences 
in the so-called racial distinctions became less important to him - 
except perhaps for a possible sense of guilt.  He most definitely 
maintained that Native Americans were an inferior peoples.

Adventures of Huckleberry Finn remains my favorite all-time book.

-- 
/Unaffiliated Geographer and Twain aficionado/