The shape of the human skull has changed significantly over the last century. This is the conclusion reached by Japanese researchers who compared the cranial structures of people from the early 20th century with those of our contemporaries. The results of the study were published in the American Journal of Biological Anthropology (AJBA).

The scientists analyzed computed tomography (CT) scans of skulls from individuals who died between 1900 and 1920 and compared them with scans of modern Japanese individuals who died between 2022 and 2024. For precision, they utilized 161 anatomical landmarks on three-dimensional models.

The analysis revealed that over the past hundred years, the skull has become more rounded; modern humans are less likely to have an elongated head shape. Furthermore, facial features have shifted: cheekbones have narrowed, the upper jaw has widened, and the nose has become thinner and more prominent. Scientists also recorded a shortening of the forehead and an increase in the bony protrusions behind the ears (the mastoid processes).

According to study lead Shiori Usui, these changes are occurring too rapidly to be explained by evolution alone. Most likely, they are linked to lifestyle factors: improved nutrition and health during childhood, as well as a transition to softer foods, which require less chewing effort and influence the formation of facial bones.

An unexpected finding was the widening gap in sexual dimorphism. Men were found to have more pronounced brow ridges, larger bony protrusions, and more prominent facial features compared to women. This contradicts the assumption that a convergence in lifestyles should have smoothed out such differences.

The authors note that similar trends may be occurring in other countries, though additional research is needed to confirm this globally.