Africans naturally have curly, kiny, and ziggly types of hair. So to go from having naturally curly hair, to the hair that sprouts from your roots..."naturally" to be "eccentric" is quite a theory. "How can something that's natural be eccentric"(80)?
(like, there's an entire scale and everything)
Of course during the 50s and the 60s, Black women were known to have pressed/straightened hair. I know that as both time and society have evolved, Black hair and its societal standards will evolve too, as they have.
Here's where it gets interesting...
At the start of slavery, to possess Euro-centric features was acceptable, and Black women began to abandon their cornrows, and their fro's to transition into a new do' that wasn't curly, or that did not resemble their original heritage. Which began the assimilation into White or European culture- Which is also exactly what Beneatha is challenging in this altercation between George and Ruth.