How Chewing Shaped Human Evolution

Chewing also known as mastication has evolved over the years 

The differences between our chewing habits and those of our ancestors offer insights into human evolution.

Their ability to effectively acquire, process, and consume food was key to their survival, and changes in how we get and consume our foods has had an effect on our masticatory system which has played a key role in our own evolution. 

The need to optimize feeding, and find more  food sources without wasting it on processing costs, is one of the main driving forces behind the evolution of mastication. 

With the invention of tools, food processing, cooking, and agriculture, modern humans have been  liberated from the lengthy time of daily chewing. 

Our  ancestors spent way more time chewing their food and  the very act of chewing requires us to expend energy. Chewing, in addition to keeping us from choking, makes the energy and nutrients in food accessible to the digestive system. The more we chew the more energy it requires the better for our digestive system jaws, teeth and muscles. Adaptations to teeth, jaws and muscles all play a part in how efficiently humans chew.

The agricultural and industrial revolution changed our foods. Which has changed our craniofacial respiratory complex affecting how we grow and develop. Our foods are now softer and more processed, as a result we are seeing more crooked, crowded teeth and smaller airways. 

It has been  suggested that before the onset of cooking and sophisticated extra-oral processing, the mastication of food could have required a much larger proportion of daily energy.

These differences can be seen when comparing apes that chew considerably more than humans, ranging from 4.5 hours  to 35 minutes a day for humans.

Chewing used to expend as much energy as walking or running because we were  chewing tougher food that takes significantly more energy. 

Studies suggest that the metabolic costs of chewing may have played an important role in our evolution. Making food easier to process through cooking, mashing food with tools and growing crops optimized for eating might have dialed down the evolutionary pressure for us to be super-chewers. Our evolving chewing needs may have even shaped what our faces look like now and explain why we no longer have room for our wisdom teeth, have more crowded teeth and smaller airways.

Kevin Boyd is a board-certified pediatric dentist with over 20 years experience. Dr. Boyd also holds an advanced degree (M.Sc.) in Human Nutrition and Dietetics and advanced education in orthodontics and dentofacial orthopedics for growing children. He is recognized as a leading clinician in the Chicago area for diagnosing and treating interferences to normal growth of the teeth, jaws and face.

He explains that compared to our ancestors, our facial skeletons are changing our craniofacial respiratory system with jaws, teeth and chewing muscles that are developing relatively small. All this is a reflection on reduced  forceful chewing from a change in diet. 

Knowing about the environmental,  societal and dietary causes that led us to get here, 

from the time that teeth begin to develop, parents can see patterns in how the child’s jaw and mouth are developing.

 What many parents do not realize is that this is a perfect time for the child to visit an orthodontist. Since the child is so early on in their oral development, the mouth is easier to manipulate and fix. 

A Chicago Orthodontist can not only see problems that are happening in your mouth in real time, but can predict future problems as well. Early orthodontics is greatly recommended for children with problems such as overly narrow bites, cross bites, and over/ under bites. 

It is much easier to fix at a younger age and can be corrected in a shorter period of time when the child is younger because the jaw bone is still growing and malleable.

A narrow arch is another problem that can be fixed effectively in younger children. A narrow arch is when the upper jaw makes a sharp “U” shape instead of the preferred wider, ovoid shape that an airway orthodontist would recommend evaluating as early as the age of 2 or 3 years old..  Narrow bites can cause many problems for patients including crowding of teeth and irregular alignment of teeth. This problem is much harder and can take far more time to repair in an adult patient.

Pediatric dentists can now observe and predict much easier how to fix these malocclusion concerns when the child is younger and is still developing. Treatment for such problems at a younger age can reduce the time spent correcting the mouth and can also reduce much of the pain that comes in treating jaw problems after the bones are already set and formed.

An essential outcome of chewing is the comminution of a food into small particles, lubricating them with saliva,  promoting the formation of a bolus (a ball of particles bound together by saliva) that can be swallowed easily and then digested. 

Teeth break foods down mechanically in the oral cavity. The energy needed to reduce food particles from their ingested size down to what is swallowed defines the efficiency of the process. Variation in diets is thought to have driven the evolution of chewing and malocclusion.

Studies show that chewing on slightly tougher material requires markedly more energy. Spending less time on mastication may go hand in hand with human evolution,  and not in a good way.

Chewing, biting, clenching, grinding and oral health are interconnected aspects of the mouth and its functions. 

Biting: Biting refers to the action of bringing your teeth together to cut or tear food. Proper biting involves an alignment of the upper and lower teeth, allowing for efficient and comfortable biting. Misalignment or malocclusion can lead to difficulties in biting, speech problems, and potential oral health issues.

Chewing: Chewing as we discussed earlier is the process of breaking down food into smaller pieces using your teeth and jaw muscles. It’s an essential part of digestion and allows for easier swallowing and digestion. Chewing also stimulates saliva production, which aids in oral hygiene by neutralizing acids and washing away food particles.

Chewing is important for your health and digestion for several reasons:

  1. Mechanical Breakdown: Chewing breaks down food into smaller, more manageable pieces, making it easier to swallow and digest. Properly chewed food increases the surface area available for digestive enzymes to act upon, enhancing the digestion and absorption of nutrients.
  2. Saliva Production: Chewing stimulates the production of saliva, which contains enzymes that begin the digestion process. Saliva helps moisten food, making it easier to swallow, and contains antibodies that can fight harmful bacteria in the mouth.
  3. Nutrient Absorption: Thorough chewing aids in the release of nutrients from food. Breaking down food into smaller particles improves its digestibility and allows for better absorption of nutrients in the digestive tract.

The number of times you should chew before swallowing can vary depending on the type of food, its texture, and your personal preference. However, a general guideline is to aim for around 20 to 30 chews per bite. Softer foods may require fewer chews, while harder or fibrous foods may require more. Chewing slowly and thoroughly allows for proper mixing with saliva and digestion to occur. 

Since becoming a myofunctional therapist and assessing chewing tongue function and swallowing the average chew time is 4-6 chews before swallowing. 

Missing teeth, crowded teeth, open bites, and crossbite are making it harder for us to chew our food and break them down before swallowing, creating a ripple effect in our body.

An open bite is a dental condition where the upper and lower teeth do not meet properly when the mouth is closed. It results in a visible gap between the upper and lower teeth when biting down. Here are some potential consequences or issues associated with an open bite:

  1. Difficulty in Biting and Chewing: An open bite can make it challenging to bite and chew food properly. The lack of contact between the upper and lower teeth can affect the efficiency of the chewing process and may result in difficulties with eating certain types of food.
  2. Speech Impairments: The gap caused by an open bite can impact speech patterns and articulation. It may lead to lisping, difficulty pronouncing certain sounds, or other speech-related issues.
  3. Temporomandibular Joint (TMJ) Problems: An open bite can cause strain on the temporomandibular joint (TMJ), which connects the jawbone to the skull. The misalignment can result in TMJ disorders, leading to symptoms like jaw pain, clicking or popping sounds, headaches, and limited jaw movement.
  4. Tooth Wear and Sensitivity: With an open bite, certain teeth may bear excessive pressure or contact during biting and chewing, while others may not touch at all. This imbalance can cause uneven wear on the teeth, leading to enamel erosion, tooth sensitivity, and an increased risk of tooth decay.
  5. Esthetic Concerns: Open bite can affect the appearance of the smile. The visible gap between the upper and lower teeth can impact self-confidence and may make individuals self-conscious about their smile.

Treating an open bite depends on its underlying causes, severity, and the age of the individual. Treatment options may include:

  • Orthodontic treatment: Braces or clear aligners can be used to correct the position of the teeth and align the bite properly.
  • Tooth extractions: In some cases, removing specific teeth may be necessary to create space and allow for proper alignment.
  • Jaw surgery: In severe cases or when skeletal discrepancies are present, orthognathic surgery may be required to reposition the jaws.
  • Myofunctional therapy: This involves exercises and techniques to improve tongue posture, swallowing patterns, and overall oral muscle function.

If you suspect you have an open bite or are experiencing any related issues, it’s best to consult with an orthodontist or a dentist who specializes in bite problems. They can evaluate your condition, determine the underlying cause, and recommend the most suitable treatment approach for you. If you have already had braces and our bite has shifted your habits could be the reason.

There can be an underlying connection between clenching, grinding (bruxism), and airway issues. This association is often seen in a condition known as sleep bruxism, where grinding and clenching occur during sleep. Here’s how airway problems can relate to bruxism:

  1. Obstructive Sleep Apnea (OSA): Obstructive sleep apnea is a sleep disorder characterized by repetitive partial or complete blockage of the airway during sleep. When the airway becomes obstructed, the body may respond by clenching or grinding the teeth as a subconscious effort to reopen the airway and facilitate breathing. This can lead to bruxism episodes during sleep.
  2. Sleep-Disordered Breathing: Sleep-disordered breathing encompasses a range of breathing problems during sleep, including snoring, upper airway resistance syndrome (UARS), and mild to severe cases of obstructive sleep apnea. The disrupted airflow and oxygen supply during these conditions can trigger clenching or grinding as a reflex to alleviate airway obstruction.
  3. Anatomical Factors: Certain anatomical factors, such as a narrow airway, enlarged tonsils, or a deviated septum, can contribute to both airway problems and bruxism. These structural issues can lead to increased resistance to airflow, and the body may respond with clenching or grinding motions to try to clear the airway.

It’s important to note that while there may be a connection between airway issues and clenching/grinding, not everyone who clenches or grinds their teeth has an underlying airway problem. Bruxism can have multiple causes, including stress, anxiety, malocclusion, and other factors.

If you suspect that airway problems may be contributing to your bruxism, it is advisable to consult with a healthcare professional, such as a sleep specialist or dentist with expertise in sleep-related disorders. They can assess your symptoms, evaluate your airway function, and recommend appropriate diagnostic tests, such as a sleep study, to determine the underlying cause of your bruxism and guide the most suitable treatment approach.

  1. Oral Health: Oral health encompasses the overall condition of your mouth, including teeth, gums, and other oral structures. Maintaining good oral health is crucial for overall well-being. Here are some key points:
    • Regular dental care: Schedule routine dental check-ups and cleanings to monitor and maintain your oral health.
    • Proper oral hygiene: Brush your teeth twice a day with fluoride toothpaste, floss daily, and use mouthwash to remove plaque and prevent gum disease and cavities.
    • Balanced diet: A healthy diet with limited sugary foods and drinks helps prevent tooth decay and supports oral health.
    • Mouthguards: If you engage in activities such as contact sports or teeth grinding, wearing a mouthguard can protect your teeth from injury.
    • Stress management: Finding healthy ways to manage stress can help reduce clenching, bruxism, and associated oral health issues.
    • Orthodontic treatment: In cases of misaligned teeth or malocclusion, orthodontic treatment may be recommended to improve biting, chewing, and overall oral health.

If you don’t have enough or any teeth to chew, it can pose challenges to your ability to chew food properly. Consulting with a dentist or a nutritionist can help you find appropriate solutions and suggest suitable dietary modifications based on your specific needs and oral health conditions.

Remember, if you have concerns about your oral health, it’s best to consult with a dentist or dental professional who can provide personalized advice and treatment options tailored to your specific needs.

I am always here to help answer any question and schedule a 15 minute call with me. If  I can not help, I can get you to a provider that can.


  1. W. Lucas, Dental Functional Morphology: How Teeth Work (Cambridge Univ. Press, 2004).,+Dental+Functional+Morphology:+How+Teeth+Work+(Cambridge+Univ.+Press,+2004).&ots=t7L3qjgV9r&sig=AroeB92wt4zS4R-9jkepLaFAkUA#v=onepage&q=P.%20W.%20Lucas%2C%20Dental%20Functional%20Morphology%3A%20How%20Teeth%20Work%20(Cambridge%20Univ.%20Press%2C%202004).&f=false