The face is probably the most important physical feature of humans. While it is known that the human face changes with age, scientists found that diet and social structure also play a vital role in its evolution.

A new research from the Arizona State University discovers that the face is actually a mirror to the past. It reflects the changes that happened through time, and says a lot about the most unique features that we use to recognize each other.

"We are a product of our past," says William Kimbel, study author and director of the Institute of Human Origins and Virginia M. Ullman Professor of Natural History and the Environment in the School of Human Evolution and Social Change.

Kimbel adds that by analyzing the processes of how humans evolved into the way they are allows them to look at the human anatomy with awe, and to ask what the different parts of the body contributed to the history of humans leading up to the modern times.

Structural Development Through Time

About 4.5 million years ago, human ancestors stood on two legs and were able to walk upright. After this, the skeletal structure of the now-bipedal creature formed really well. People started to develop longer limbs, and were able to stabilize the functionality of bipedal locomotion.

The structure of facial bones also had a fair share of changes. In fact, the scientists think that the skull and teeth provide a good resource for tracking history and describing evolution of species. Among the important factors of the changing skull are growing brain and adjustments to breathing and energy demands. The most vital keys for skull changes, however, are the changes that happened to the jaw, teeth, and face as people adapted to changes in diet and eating behaviors.

Diet Is A Vital Key

Diet played a huge role in explaining the changes that happened to humans' facial features. In the early days, ancestors used to eat hard plant-based food that necessitate big jaw muscles and cheek teeth to break down food. Moreover, faces back then were broad and deep, with parts of huge muscle attachments.

The environment changed through time, and the dry and less wooded conditions made the early Homo species to use tools to break down food or cut meat on a routinely basis. With this, the jaw and teeth were relieved of large pressure, and the face subsequently became more delicate, with a flattering expression.

Social Structure And Emotional Changes

Aside from diet and lifestyle, the research team also found that non-physical things also contributed to facial changes. After all, the face is highly involved in social interactions, emotion, and communication. As more challenges come along their way, ancestors were able to learn how to make different facial expressions, enhancing nonverbal communication.

Through time, they became more cooperative and social. People became less aggressive, and so did the large brow ridges and sharp canine teeth.

The study was published in the journal Nature Ecology and Evolution.

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