"ARe there any biologcial differences in African Americans as a group that would prevent them, if they worked very hard, to achieve equality with whites as a group in terms of wealth, education, poltical representation, ect?"
Absolutely not! The biggest thing I see holding it back is the culture and those who try to excel at those things being labeled as acting 'too white' or a traitor to their race/culture. Holding back their own culture from advancing then blaming everybody else for the consequences. And I'm talking about today, not talking about 40+ years ago.