In chapter seven the author discusses dialects, how different regions can generate linguistically-distinct words, grammar and pronunciation.
She talks about AAE, African American English, sometimes derogatorily referred to as Ebonics. Surprisingly AAE is remarkably consistent across many regions, and shares some grammatical features with West African languages, supposedly.
I've always had a problem with it myself. People who speak AAE who are not Black are roundly criticized, which signals to me that it's not a real dialect. Many of the phrases and words signifying AAE are simple mispronunciations, like "axe" for "ask" or "libary" for "library" or "doze" and "dem" for "those" and "them." Others are misuse of verb tenses, like "Frank be running" or "Tyrone work at the bar." Others are dropped articles, like "she my sister" or "he got game."
These strike me as less dialectical, and more propagated errors. At what point does lack of education cross over into being a legitimate dialect?
Poor people in Appalachia (of any color) are often unintelligible to outsiders. If they wish to conduct business with the wider world however they quickly learn to modulate their speech.
Huckleberry Finn and Porgy and Bess parodied Negro speech patterns of the time, and it was widely recognized as evidence of the poor education of the descendants of slaves. When did this become a valid dialect?
I suspect, without having researched it, that the purported ties to West African languages were created after the fact. I somehow doubt that any vestiges of their native tongue remained ten generations later.
Mrs NoCo pointed out that highly educated African Americans, such as you see hosting nationwide television shows, can lapse in Ebonics quite easily when interviewing people from a lower educational bracket. Maybe learning to speak "the Queen's English" is a requirement for their job, but there should be no shame in lapsing into dialects when appropriate.