When it comes to our growth, we humans prefer to be patient. Only chimpanzees are able to extend the time between developmental milestones.
Even chimps can get down with a full set if they are sexually mature. Homo sapiens do not grow their final teeth until they are almost out of their teenage years.
Despite their critical role in evolution tracking, the mystery of the molars remains a difficult one to solve. Researchers at the University of Arizona, USA think they may have solved the mystery.
Halszka Glowacka, an anthropologist and author, says that one of the most mysterious aspects of human biological development is the exact synchrony between life history and molar emergence.
Glowacka was assisted by Gary Schwartz, a paleoanthropologist at the University of Arizona's Institute of Human Origins. He helped to collect examples of skulls from different locations so that they could be compared.
Researchers were able to turn the bones and teeth from 21 primate species into 3D models to show that the timing of our adult malocclusions is influenced by the delicate biomechanics of our skulls.
The adult teeth that we use to grind food into paste usually emerge from our gums at six, twelve, and 18 years old (give or take).
Some primates have their adult molars sooner than others. The chimpanzee (Pan. troglodytes), gets its molars at three, six and twelve years. The yellow baboon (Papio cynocephalus), has its last adult molars by age seven. Macaca mulatta, the rhesus macaque, is done by six.
Space is an important factor that will affect when your teeth appear. Space is a key factor in the timing of when teeth can appear. If your jaw is not large enough to accommodate a full-sized adult-sized set of dental implants, it's best to squeeze them in.
Humans don’t have much mouth space. Impacted wisdom teeth are a problem for many species. This doesn't explain how they appear so late in life, nor why they seem to be causing more problems.
It's not a good idea for a tooth space to grow if it isn't already there. Teeth can't just crunch on their own. There are a lot of muscles and bones supporting them. This ensures that enough pressure can safely tear up and grind our food.
It's the'safety factor' that is responsible for our slow growth of teeth.
Schwartz says that "it turns out that our jaws are very slow, probably due to our slower life histories and, combined with our short faces delays when a mechanically secure space, or a sweet spot', is available. This results in our very late ages for molar emergence."
Primates' back molars are located just in front two temporomandibular joint, which together form a hinge between the skull and your jaw. The two pivots must work in perfect sync, unlike other joints in the body. To get you chewing and biting, they must transfer some force to one or more points.
This three-point process is called the constrained-level model in biomechanics. If you place a tooth in an unsuitable spot, the forces generated by this model can cause damage to a jaw that isn't large enough to handle it.
The time it takes to create a proper structure for teeth near the muscles is shorter for species with longer jaws.
Humans with significantly smaller faces have no luck. They must wait until their skulls are developed enough to resist the force of each set.
This will allow us to assess dental conditions such as impacted teeth. It could also help paleontologists better understand the evolution and evolution of jaws in our hominid ancestors.
Glowacka stated that "this study provides a powerful new way to view the long-known links between dental development, skull growth, and maturational profiles."
Science Advances published this research.
