that low amount
NO, this is again ambiguity. Their is no low amount of DNA that account for "race" difference. Their is low amount of DNA that account for physical traits, but these little amounts are not distributed within a "race". - please watch "The power of an Illusion!"
Although race is a social construction, it is also true that race has real consequences because people do perceive race as something real.
Yes
The reasons for doubting the biological basis for racial categories suggest that race is more of a social category than a biological one.
It is not doubting the biological basis... it their is no biological basis... please be more clear! It is ok, we know that science is also context based, it uses scientific method but what is studied, how it is questioned, framed, funded is context dependent. The goal of science is to have theories, and constantly question them... it is a social construct to think of science as the proved truth, it is not the purpose of science... So it is not saying science is not worth to say that the "theory of race" was a fraud and that current research have proven with many means it is not based on facts and evidences. People that say that if we question the biological base of racism it means we have que question science are, to my mind, misunderstanding what science is.
human race began thousands and thousands of years ago in sub-Saharan Africa
OK it is written here.... but the previous paragraphs, to my, are hiding this last paragraph in euphemism about the concept of race. There is NO scientific evidence that it is based on biology - let's be more clear about that!