Tim Schoon / University of Iowa
Comparison of Homo Sapiens (left) and Neanderthal (right) skulls. Homo sapiens has chin, the Neanderthal does not.
A fundamental difference in development can explain why modern humans have smaller and flattened faces than neanderthals and chimpanzees.
The facial bones of the Homo sapiens grow more slowly and stop growing earlier than those of Neanderthals, whose faces continue to develop until the beginning of adulthood, according to a new study, on the 24th in the 24th Journal of Human Evolution.
The study analyzed the skulls of 174 individuals of three species – modern, neanderthal and chimpanzees – in various phases of development, from childhood to adulthood. The investigation focused on the medium-sided region and resorted to 3D models and microscopic bone analysis to follow growth standards.
“These two human species followed different development trajectories of their facial bones, ”said Alexandra Schuh, a postdoctoral researcher at the Max Planck Institute of Evolutionary Anthropology to.
The study concluded that neanderthals, such as chimpanzees, had a consistent bone formation since the beginning of life, which resulted in larger and more protruding faces.
In the case of modern humans, they had a much higher degree of bone resorption, A natural process in which bone tissue is decomposed that limits growth and leads to the characteristic smaller human face.
This development difference seems to be exclusive to the Homo sapiens.
“The cessation of earlier growth is a distinctive characteristic of our species,” said Schuh: “We have identified a unique development pattern observed exclusively in Homo sapiens.”
The reason why Neanderthals have developed large faces continues to be debated, with theories ranging from adaptation to cold climate and higher metabolic needs to food requirements and the use of teeth as tools. However, the evolution of smaller human faces may be linked to factors such as cooking, which reduces chewing needsor increased brain size, which can alter the shape of the skull.
Although the study does not explain exactly why humans have developed smaller faces, it gives us strong clues about how change happened.
