Posted by Chirag Sheth on behalf of Ethan Rohan Ananda-Rajan

An anthropological discussion on the increased prevalence of third molar dental complications in humans as a result of changing diet and food preparation over the past 30 millennia

Human evolution is ongoing.  About 2.4 million years ago in the Pleistocene epoch the first hominids arose, the taxonomic family to which all organisms capable of reading this blog post belong. During this period the branches of our genus’s (homo) evolutionary tree were spreading all over Africa. With the notable arrival of Homo habilis (which literally means handyman) came the familiar humanoid form with the notable differences of a smaller brain, larger teeth, protruding lower jaw and longer arms more adapted for climbing. Soon after, Homo erectus (2,000,000 years ago) and later Homo neanderthalensis (200,000 years ago) arrived on the scene, followed by their contemporary: Homo sapiens. However, following the end of the last ice age 12000 years ago, the Holocene epoch began, and the unchallenged rule of the humans began.

Archaeological investigation of ancient artifacts
Archaeological investigation of ancient artifacts

Since then humans have changed the world beyond recognition

Shaping our surroundings to suit our needs as opposed to adapting ourselves and evolving to suit our surroundings as every other organism has, but even as we mould the world around us for our own convenience the unstoppable drive of natural selection even now continues, humans continue to adapt and change and modern man is indeed still evolving. In this article I will discuss one of the ways in which we are still adapting, through a factor which affects millions of people per year, and which has caused more than a third of the population to lose this body part entirely: the routine operation considered by many to be the most uncomfortable and feared procedure outside of urgent medical interventions, the evasive and notorious third molar.

Cast of skull
Cast of skull of ‘Australopithecus africanus’

We have been evolving since the inception of life to get to where we are now and for the past 3.8 billion years of life on earth change has been gradual but constant. Despite our popular belief and perhaps arrogance in thinking we are the perfectly evolved organisms who shape the world to fit us, we are in fact still changing.

What about the future?

While many anthropologists, futurists, and indeed science fiction writers have speculated that the future of human evolution may involve bigger, more muscular and dextrous thumbs for mobile phone usage or computer chips implanted inside our brains, the real changes appear to be much more mundane, but nonetheless real. The real changes affecting humans in what many may still consider evolution include getting taller, losing the ability to digest milk, sickle cell anaemia and the associated resistance to malaria in Africa, and yes, agenesis of the wisdom teeth.

A panoramic radiograph created with a CRANEX® D digital panoramic X-ray system
A panoramic radiograph created with a CRANEX® D digital panoramic X-ray system

Human ancestors had larger, more prominent jaws, adapted to eating harsher, firmer foods, including raw meat and unprocessed solids. In addition, the larger jaws facilitated the involvement of all 3 molars and frequently would cause the grinding action and attrition of teeth, which gradually migrated forwards to replace those lost, in a phenomenon known as medial drift, an action that, in modern humans causes pathological crowding. In our ancestors however the migration and attrition of more anterior teeth was a natural replacement mechanism similar to that exhibited by many other animals. The loss of teeth of course was not such a problem with the significantly lower life expectancy.

The primary cause in the human jaw shrinking and having less anatomical space to accommodate the full dental arcade is the development in cooking and cultivation. Softer foods due to cooking meat and processing grains in the last 12,000 years made our diets simultaneously more nutritious and softer on our teeth. A smaller demand in more recent times of a robust jaw, masticatory muscles, and wear on teeth is thought to be the chief reason for smaller jaws with less space, and a corresponding problem in the eruption and development of the wisdom teeth.

Agenesis (the complete absence of wisdom teeth) is present in around 35% of the population

This appears to be the natural human adaptation to this problem. Indeed, they may be considered the lucky ones, third molar surgery can be painful and expensive but still less painful and problematic than an impaction or infection caused by an erroneous eruption. As the organ becomes increasingly vestigial, instead of wasting energy in creating and making space for an extra tooth, and having to deal with the possible complications, the body simply develops without it. Third molars are the only teeth to develop entirely after birth, making the lack of development and budding of the progenitor cells much more common.

The third molars develop after birth

Human adaptation appears to be moving away from the development of the third molar. The loss of the third molar is different to other organs becoming vestigial such as the appendix.  While the appendix shows shrinkage there are very few humans who have ever reached mature adult age without developing it completely.

A soft diet may accelerate the evolutionary loss of the third molar

Good or Bad?

So is the increase in incidence of third molar agenesis a good thing or a bad thing? Can we consider those who do not develop the wisdom teeth more evolved? And is the availability of softer, easier to chew and digest food worth the trade off of the loss of a tooth and in many peoples cases the fear and pain of an extraction? Perhaps the soft lifestyle we live now promotes degradation. Or perhaps the ability of humanity to adapt and evolve should include the ways in which we are able to shape our environmental resources to our needs, and the disappearance of the third molar should be considered an evolutionary change as much as the ability to make and process foods to become as soft as applesauce, which caused the loss of M3 in the first place.


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