To clarify, I didn't mean to say that everyone with a national identity from an African country is "black". Of course there are a lot of people of primarily non-African ancestry, such as the Dutch and Arabs, who have settled on the African continent over the centuries. What I was referring to was a biologically (indigenous) African identity, much like you would consider Native Americans to be biologically (indigenous) Americans. And with few exceptions, pretty much all peoples whose ancestry is by and large biologically African are dark-skinned. They don't express the genetic alleles for lighter skin that you see in Europeans, Asians, Native Americans, Polynesians, etc.
This is not true at all. And this has been disproven in multiple studies. The caste system can't be racist because it's based on birth, not skin color. That means that caste are inherited almost always. If a darker indian has a lighter child, they are STILL apart of a caste. They don't automatically move out of it because of skin color.
I never intimated upward mobility in caste system, it is still based on skin tone regardless. And bigotry, racism regardless if it is inherited, is still wrong, it is what it is regardless.