Why are modern humans the only species that has a chin or chin? According to research from the University of Iowa, it is not due to the action of mechanical forces, such as chewing, but to purely evolutionary reasons: as our face has become smaller, it has tended to expose a bony prominence at the bottom of the head .
If you look at the skull of a primate or a Neanderthal and compare it with the modern human, you can see that they lack that trait that defines us. “Although it seems a trivial question, the chin is interesting because no other species has it “, says Nathan Holton, one of the authors of the work and an expert in craniofacial and mechanical features of the aforementioned university.
This evolutionary adaptation that has been changing the shape and size of the face is possibly related to changes in hormonal levels as as a species we became more social and domesticated . If this finding is confirmed, it can shed light on the process of formation of that distinctive trait.
Through biomechanical analyzes and facial and cranial measurements of 40 individuals, young children and adults of various ages, the team from the University of Iowa concluded that the action of mechanical forces such as chewing does not seem capable of producing the resistance necessary to create new bones in the body. lower jaw.
Rather, it would be said that the appearance of the chin in modern humans was produced by pure geometry . As we evolved from archaic hominids to modern humans, the size of the face was greatly reduced – ours is 15% smaller than that of Neanderthals – and the chin was left as a bony prominence, the adapted emblem at the bottom of the face.
Robert Franciscus, an anthropologist at the University of Iowa, believes that the human chin is a side effect of the change in our lifestyle , which began about 80,000 years ago and accelerated 20,000 years ago with the migration of modern humans from Africa.
Since these evolved from groups of hunter-gatherers disconnected from each other to gradually form larger cooperative communities and social networks of greater scope throughout the territory, this expanded their forms of artistic and symbolic expression .
Males, in particular, became calmer, less likely to fight incessantly for territory and belongings, and more in favor of forging alliances and exchanging fruitful goods and ideas for individuals and the collective. This change in attitude was coupled with a drop in hormones such as testosterone, which produced alterations in the craniofacial region, prompted a reduction in the size of the head and led to the emergence of the chin .
According to Franciscus, “for socialization to be possible, males had to tolerate each other. They should express curiosity rather than aggressiveness, and that’s what facial architecture is for ”.
