Until about 35 years ago, linguists (and, if we're being honest, us laypeople as well) believed that for the last 300,000 years, human beings were able to communicate much like we do today. Well, at least from a physical standpoint. The human mouth hasn't changed a ton. However, in 1985, linguist Charles Hockett posited that for the longest time our Neolithic ancestors weren't able to make "f" and "v" sounds, both of which contain some of the funnest verbiages for fornicating.
As it turns out, our meat-loving ancestors' mouths were shaped so that our top incisors rested atop our bottom ones. which is great for chomping into festering wildebeest carcass, but makes it impossible to form these sounds known as labiodental consonants. Go ahead, align all your teeth and then say: "Victoria fried a fresh fish in a vat of fat." Congratulations, you just sounded like a ridiculous caveman.
So what changed? Food did. Hockett first observed that these labiodental sounds were more prevalent in societies that ate a lot of soft food, something we as hunter-gatherers couldn't pronounce, let alone produce. But when most of mankind sold out and went agrarian, there was no longer a need to be able to chew through a week-old buffalo butt. Over time, or lower jaw started to shrink and develop an overbite, the ideal dental position for telling someone to go eff themselves through a mouthful of pudding.