You may get to this later in your (awesome) article, but I read (and I can't remember where) that the genes that govern cognition and behavior developed far earlier than those that govern skin color - skin color simply lightened when people migrated to cloudier places so people could get enough vitamin D or absorb calcium or whatever. Thus, distinctions between the "races" are only skin deep. Any behavioral distinctions are mostly due to environment, eg the stress brought on by being in a racist world and subjected to racist policies, and those arose because we're such visual creatures - we think because something looks different, it is different.

Anyway, I've thoroughly enjoyed reading this so far. Thank you.