Head to Toe - Daniel Lieberman tracks the evolution of the human head.

By: Jonathon Shaw

         Interesting article explaining some of the reasons why modern-day humans  have smaller jaws than our ancestors. As we know, smaller jaws lead to smaller airways, worse nasal breathing, dental crowding, etc.  The article explores the work of Daniel Lieberman- one of my favorite anthropologist whose book, Evolution of the Human Head, I highly recommend. 

    "Lieberman wondered whether the modern diet of soft food might be a contributing factor. As bones grow, their size and shape respond to biomechanical stresses, so he decided to study the effects of chewing hard versus soft food on the growth and development of the skull in various animal species. In one experiment, he fed soft food to one group of pigs, hard food to another. The stresses of chewing made the upper and lower jaws of the pigs eating hard food grow larger. The study suggested that there is a link between smaller jaws and regularly chewing very high-quality soft food. And humans, he points out, have never had greater access to high-energy processed food than they do now. “I think many people today never have to actually chew anything all day long,” he says. “You can see the effects of that shift in our heads now in terms of molar impactions”—small faces and jaws leave too little room for teeth."

Source: Harvard Magazine
https://harvardmagazine.com/2011/01/head-to-toe