The general argument is that the upper classes of Rome and Greece were Northern Europeans, while the middle and lower classes were darker-complected whites. There is an unvariable claim that miscegenation caused the decline of the patrician families and so the decline of Rome.
Hi! I discussed at least one version of that argument here.
Huntington argued that Romans (of all classes, not just patricians) were originally similar to virtuous Nordics that thrived in a cold climate, but when the Mediterranean warmed up, the population adapted and became like the sluggish Spaniard or African, and that loss of moral vigor caused both the end of the Republic and the fall of the Empire.
It's astounding and absurdly argued.
Hi there!
Please remove the link that is included in your expanded text. We don't want to give white supremacists a platform in this sub and thus ask users to remove links to their propaganda material.
Thank you!
To add on to what /u/LegalAction said, I would direct you to look at the Wikipedia page of the Severan Tondo here. It is a contemporary depiction of the emperor Septimius Severus, along with his wife and two children (Caracalla on the right, and Geta, on the left without a face), who was one of Rome's most successful and powerful emperors. You can see that he has quite a dark complexion.