Human facial structure evolved to tolerate punches to the head, according to new research that suggests our ancestors spent a lot of time fighting.
Such ancestors likely included the australopiths, which lived 4 to 2 million years ago in Africa.
"The australopiths were characterized by a suite of traits that may have improved fighting ability, including hand proportions that allow formation of a fist; effectively turning the delicate musculoskeletal system of the hand into a club effective for striking," David Carrier, lead author of the study, said in a press release.
"If indeed the evolution of our hand proportions were associated with selection for fighting behavior you might expect the primary target, the face, to have undergone evolution to better protect it from injury when punched," added Carrier, who is a University of Utah biologist.
The researchers found that bones that suffer the highest rates of fractures in fights are the same parts of the skull that exhibited the greatest increase in sturdiness during the evolution of our early human relatives. These bones are also the parts of the skull that show the greatest difference between males and females in both australopiths and humans today.
"In other words," Carrier said, "male and female faces are different because the parts of the skull that break in fights are bigger in males. Importantly, these facial features appear in the fossil record at approximately the same time that our ancestors evolved hand proportions that allow the formation of a fist."
He continued, "Together, these observations suggest that many of the facial features that characterize early hominins may have evolved to protect the face from injury during fighting with fists."
"Our research is about peace," Morgan explained. "We seek to explore, understand, and confront humankind's violent and aggressive tendencies."
"Peace begins with ourselves and is ultimately achieved through disciplined self-analysis and an understanding of where we've come from as a species. Through our research we hope to look ourselves in the mirror and begin the difficult work of changing ourselves for the better."
