For 200,000 years before grain agriculture, the human jaw and the size of teeth were basically static. However, for the last 10,000 years or so, which coincides with the advent of agricultural farming, the width, length, and shape of the human jaw have been decreasing and changing slowly while the size of the teeth have changed very little.
So, what is going on?
Although genetics play a role, our environment has been the dominant contributor influencing poor jaw development. There appear to be three major external factors that are affecting the size and shape of our jaws. Two are the results of the onset of agricultural farming, and the more recent factor is the result of how babies are fed. They are:
- Decrease in Nutrient-Dense Foods
- Increase in Soft Foods
- Decrease in Breastfeeding
DECREASE IN NUTRIENT-DENSE FOODS
Nutrient-rich food sources declined after agricultural farming provided a significantly increasing proportion of processed foods to our diets. The lack of necessary nutrients in the acellular carbohydrates of these grain and sugar products compromised bone metabolism.1, 2
Dr. Weston A. Price, a dentist, published Nutrition and Physical Degeneration in 1939. Price documented numerous observational examples of primitive peoples who had healthy dentitions and others who had various dental problems including gum disease, tooth decay, and poor jaw development. He identified that those with healthy dentitions generally ate nutrient-dense foods, and those with unhealthy dental conditions regularly consumed diets high in flour, sugar, processed vegetable fats and processed foods. Price implicated a lack of both fat-soluble vitamins and trace minerals to be the most important deficiencies causing dental problems.
Since then, there have been numerous observations among hunter-gatherer societies who had relatively healthy bodies with little or no chronic disease. Those hunter-gatherers who continued to eat their natural diets had healthy dentitions and those who left their traditional diets and began to eat a “western diet” developed dental problems and jaw shrinking and had offspring with increased dental abnormalities.3
INCREASE IN SOFT FOODS
Soft food sources, which reduced the physical stimuli on the jawbones and muscles of the jaw, increased after agricultural farming.
Processed grains and starchy foods provide a soft diet. Recent research has demonstrated that softer diets created less mechanical stimuli to the muscles and bones of the jaw resulting in a slow decrease in the density and the dimensions of the jaw over the course of time. Jaws didn’t need to be as strong or as large if the foods were less hard and less strenuous to chew. Rather than happening over an evolutionary time-scale, the change to the mandible was happening on an individual level as each child was growing up.4
DECREASE IN BREAST-FEEDING
Breastfeeding decreased after bottle-feeding became commercialized in the 1800s, which had a dramatic effect on the development of the jaw.5
Evidence suggests early humans breastfed until about three or four years of age. In the United States in 2011, 79% of newborn infants started to breastfeed. However, of infants born in 2011, 49% were breastfeeding at 6 months and only 27% were still breastfeeding at 12 months.6
Breastfeeding provides optimal oral mechanical stimulation for the jaw’s normal development. When infants breast-feed, they form a deep latch onto the breast. They open wide and take in enough breast so that the breast is pressing up against their palate. Babies do not merely “suck” the milk out, but instead they use their tongue in a U-shaped curve on the breast. In a wave-like motion they “milk” the breast to receive its nourishment. Two developmental actions take place: (1) a rhythmic action of the tongue “milking” the breast, which presses on the palate, and (2) the subsequent action of swallowing. Both actions play a critical role in proper stimulation and development of the dental arches, palate, jaw and muscles. As the baby grows, the breast continues to conform to the baby’s mouth.7
When bottle-feeding replaces breastfeeding, the unnatural nipple on a bottle does not fill or conform to the baby’s palate, and therefore does not stimulate any widening of the palate to ensure room for future teeth. Also greater suction forces are required during bottle-feeding. This forceful action causes the cheeks to draw in, putting pressure on the gums and alveolar bone, affecting the position of the teeth. As the baby grows, the bottle nipple remains constant and does not adapt to the developing mouth of a growing child, further compromising normal bone and muscle development
These are observational studies, and there is controversy about the significance of the factors I have discussed. But, eating nutrient-dense foods that represent the nutrition of our primal ancestors will enhance our body’s ability to do what it was designed to do. In addition, we should include raw foods as well as crunchy foods like nuts and seeds to stimulate and exercise the muscles and bones of the jaw. We need to chew our food thoroughly. Mothers should breast feed their children for as long as prudent. Our health and our children’s health are dependent on these primal and natural lifestyles.
Dr. Danenberg is a periodontist in South Carolina who has been in practice for 40 years. Within the last 4 years, he has included Laser Periodontal Therapy as his primary treatment for periodontal disease. The procedure is called “Laser Assisted New Attachment Procedure” or “LANAP”. The last two years he has incorporated a lifestyle program for all his periodontal patients including an ancestral diet to enhance their overall body’s health and function. In July of this year he was awarded the designation, “Certified Functional Medicine Practitioner.” For more information, please visit www.DrDanenberg.com.
 Tucker KL (2009) Osteoporosis prevention and nutrition. Curr Osteoporos Rep 7:111–117
 Spreadbury I. (2013). Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity. Diabetes Metab. Syndr. Obes. 5, 175–189
 Am J Clin Nutr March 2000 vol. 71 no. 3 665-667
 Sardi M, Novellino PS, Pucciarelli HM. 2006. Craniofacial morphology in the Argentine Center-West: consequences of the transition to food production. Am J Phys Anthropol 130: 333–343.
 Stevens EE, Patrick TE, Pickler R. A history of infant feeding. J Perinat Educ. 2009;18:32–39.
 CDC. Breastfeeding Report Card. Rep. Atlanta: Center for Disease Control and Prevention, 2014. Print.
 Palmer B. The influence of breastfeeding on the development of the oral cavity: a commentary. J Hum Lact 1998; 114:93-98.