I know some guys hear are historians and u/AlfredicEnglishRules is an anthropologist. I was listening to a podcast and someone brought up some groups in America use slang predominately because their biology makes English difficult for them. I'm wondering how biology affects language? Is it just an IQ thing, or are there subtle differences in vocal chords? Or is it bullshit?

I can understand cultural differences shaping languages. And I've heard evolutionary differences, like early men having to increase their vocabularies to include dogs in their hunting.