Sadly, all the articles are locked behind a paywall but the video is free to view and has science writer Ann Gibbons discussing how the practice evolved through the ages and how archaeologists have been uncovering the evidence.
If you can’t stump up the cash for what looks like a genuinely fascinating issue there’s more discussion from the latest edition on the podcast where the science of racism and prejudice is explored.
Link to locked special issue.
Link to video.
Link to podcast