Our ancestors ate a wide range of foods with wisdom teeth, also known as third molars. But as they evolved, wisdom teeth became vestigial organs like the appendix, coccyx, muscle of ear, semilunar fold of cornea of eye, and body hair.
Wisdom teeth erupt commonly between the ages of 18 and 21. But in some people, it may erupt as early as 13 years old or as late as 25 years old. In total, there are four wisdom teeth, one in each quadrant of the oral cavity. They erupt partially in some people and not at all in others, resulting in an "impacted third molar." Wisdom teeth get impacted when they don't have enough space to erupt.
In his book, "The Descend of Man, and Selection in Relation to Sex" published in 1871, Charles Darwin mentioned many vestigial organs, which included the wisdom tooth.
How did our wisdom tooth become a vestigial organ?
Early humans' diet included roots, nuts, foliage, seeds, and raw meats. By the time they reached their late teens or early twenties, their first and second sets of molars may have already experienced significant wear and tear. Due to this, their body compensated by producing a third set of molars.
Over the centuries, humans have developed new techniques for preparing and processing food. The advent of agriculture about 10,000 years ago made humans consume soft foods. As a result, their teeth underwent less wear and tear, and the use of third molars decreased. Aside from that, the diet change resulted in less forward growth of the jaws and difficulty incorporating third molars.
To comprehend the process of evolution, it is necessary to recognize the importance of wisdom teeth in genetics and evolutionary biology.
Agenesis of wisdom teeth
Agenesis is the lack of development of an organ. Wisdom tooth agenesis differs from situations in which the tooth does not typically erupt or stays impacted within the jaw. Wisdom tooth agenesis prevalence varies among populations, reaching over 100% in Mexican Indians and being essentially nonexistent in Tasmanians. Some research has found that wisdom tooth agenesis is attributed to genetic variations among populations. In today's population, at least 53% of people have at least one wisdom tooth.
Wisdom teeth in modern humans
Along with evolving into a vestigial structure, the wisdom tooth has become a source of concern for many people today. Despite changes in the human genome that have led to smaller mouths, the genes for wisdom teeth have not yet been completely eradicated. Hence, it became difficult for smaller mouths to incorporate wisdom teeth, which often results in impaction, partial eruption of wisdom teeth, and crowding in the entire dentition. Impacted teeth cause painful ulcers in many people. Similarly, partially erupted wisdom teeth can also cause a variety of problems. Many dentists recommend wisdom teeth extraction as a solution to these issues.
Clinical significance of wisdom teeth
Wisdom teeth are the most commonly impacted teeth in the human oral cavity, which increases the risk of dental caries and periodontal disease. If the wisdom tooth completely erupts, then its treatment for caries and other diseases is the same as any other tooth in the mouth. Pericoronitis, or inflammation of the tissue surrounding the tooth, is more likely when it is partially erupted or impacted. It can cause severe pain and discomfort in affected individuals. The treatment of pericoronitis includes oral antibiotics and operculectomy. If it is severe, then extraction is advised.
Other pathologies include pulpitis, pericoronitis, cysts, and abscesses
Extraction of wisdom teeth
Around 5 million people get their wisdom teeth removed every year. The people who mostly undergo wisdom tooth removal are late teenagers and young adults. The extraction of wisdom teeth is not required if they have fully erupted and are healthy. But when they have partially erupted, cleaning becomes difficult, which results in infection. And if they are impacted, then it can cause cysts or abscesses. These conditions can be painful, and even if antibiotic treatment is given, there are high chances of recurrence. Hence, in these cases, extraction is advised. The extraction of wisdom teeth is also advised in some orthodontic cases to gain space in the dental arch.
The frequent impaction, decrease in size, and agenesis of wisdom teeth could be the final step towards their complete elimination from our oral cavity..
