The title of this post is also a title of a book by Noel Ignatiev, referenced earlier on this blog. Razib Khan (on UnHerd) has resurrected it to describe the time around 4500 BC, when Neolithic farmers invaded Ireland and displaced an earlier hunter-gatherer culture. According to Khan, genetic analysis reveals these hunter-gatherers were “dark skinned and light-eyed” (like the Cheddar Man) while the invaders were “light-skinned and dark-eyed.” Apparently the “light” genes for both skin and eyes ultimately triumphed in the Irish phenotype, although many subsequent invasions contributed.