Slower body development over the course of life, as well as smaller jaws and retracted faces in humans than in chimpanzees, may explain why molar teeth grow much later in humans than in our cousins, a new study suggests. study finds.
While chimpanzees get adult molars – the chewing teeth towards the back of the mouth – when they are about three, six and 12 years old, humans grow into adulthood at around 6, 12 and 18 years of age.
For many decades, scientists have known the close relationship between the rate at which adult molars reach their mouths with the overall rate of body growth in primates.
According to anthropologists, modern humans grow very slowly and their adult molars erupt very late in life, later than any other living or extinct primate.
“One of the mysteries of human biological evolution is how the precise synergy between molar emergence and life history came about and how it is controlled,” study lead author Halszka Glowaca of the University of Arizona said in a statement.
In the present study, published in the journal Science AdvancesIn this study, scientists analyzed primate skulls and developed a model that explains the coordination between facial growth and the mechanics of chewing muscles.
Because of a delicate dance between the speed of facial growth and the emergence of molars, they state that these chewing teeth come in only when sufficient “mechanically safe” space is created.
If the molars erupt “prematurely,” the researchers say, the teeth will disrupt the fine-grained function of the entire chewing apparatus and damage the jaw.
They say this understanding could help predict not only the conditions in the mouth where adult molars erupt but when they do.
Since the molars do not erupt until a point when sufficient facial growth has occurred, the scientists believe that “better details of the model to help understand the occurrence of impacted wisdom teeth in humans may be explored in more specimens”. May go.”
In the research, scientists created three-dimensional bio-mechanical models of skulls in nearly two dozen different species of primates ranging from tiny lemurs to gorillas.
These models also included the attachment position of each major chewing muscle during the growth period in these primates.
By simulating jaw growth at different rates in each of these primate models, scientists can understand the way in which each emerging molar syncs up with the growing and moving chewing system of the jaw.
“The precise biomechanical relationship between growing faces and increasing chewing muscles is a close and predictive relationship between dental development and life history,” the scientists said in a statement.
In humans, they say, delayed molar eruption is the result of the development of overall slower facial growth coupled with smaller jaws and faces located directly beneath our brains.
“It turns out that our jaws grow very slowly, possibly due to our overall slow life history and, in combination with our small faces, a mechanically safe space – or ‘sweet spot’, if you will – to be available. But there is a delay, resulting in the emergence of our very late molars,” says another co-author of the study, Gary Schwartz.
Scientists believe the findings may help advance the clinical understanding of wisdom teeth.
Credit: www.independent.co.uk /