From the eyes and brain to the heart or skin, almost every detail of the human body has a correspondent in the animal world. But there is a feature that belongs to us exclusively, Homo sapiens, and which no other mammal has: chin. The mystery of its origin and function has confused decades in a row on anthropologists and evolutionary biologists, who acknowledge that there is no clear evidence to explain.
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Chin, exclusively human feature
If for many body structures we can identify recurrent models, the chin remains a singular case. It does not appear in other mammals, not even in the close men of man, Neanderthalia.
This uniqueness transforms it into a controversial topic for anthropologists and biologists.
Professor Max Telford at University College London points out that the research limit is here: in the absence of a convergent phenomenon, we have no test criteria.
The assumptions are not missing. Some believe that the chin would have strengthened the jaw in the physical confrontations in prehistory. Others see it as an aesthetic artifice, meant to enhance the male beard.
There are also theories that bind its appearance with changes in the diet: with the invention of cooking and the transition to softer foods, the jaw would have reduced, and the chin would have remained as a non-function vestiu.
However, none of these explanations have solid experimental evidence. Unlike other features, there are no similar examples in nature that allow assumptions to test. Without convergent evolution, the chin remains a mystery.
Telford explained to The Conversation that “As the chin is a specific feature to Homo Sapiens, although several theories about its function have been proposed, there is no comparison mechanism, such as convergent evolution, which will allow us to check which is correct.”
Chin, a mystery that exceeds science
The study of convergent evolution shows how much we can understand about the function of a feature when nature repeats it independently.
The examples abound: the size of the testicles in the monkeys, the way the birds were wrong as close relatives, or common adaptations to marine and terrestrial mammals. These parallels turn biology into a huge laboratory where models can be tested, writes BBC.
In the case of the chin, however, everything stops. It is unique to our species and has no evolutionary correspondent. Therefore, the explanations remain at the hypothesis stage, without experimental evidence.
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