A new study, published in Biological Reviews, points out the possibility that human facial features evolved over time to better withstand punching.

Over time, the human face became more robust in order to protect it against repeated impact by smaller objects like another person’s fist, the research said. “When modern humans fight hand-to-hand the face is usually the primary target,” David Carrier, co-author of the study, said in a press release. “What we found was that the bones that suffer the highest rates of fracture in fights are the same parts of the skull that exhibited the greatest increase in robusticity during the evolution of basal hominins.”

Facial features are some of the most sexually dimorphic parts of the human skull — meaning they contain the biggest physical differences between males and females. The authors believe that the protective buttressing hypothesis also coincides with the notion that “modern humans can accurately assess a male’s strength and fighting ability from facial shape and voice quality,” which explains why a powerful neck and jawline are popularly considered attractive or a sign of strength, the Medical Daily reported.

Carrier and his fellow researcher, Michael H. Morgan, both from the University of Utah, have examined the role of violence in evolution. They believe that violence plays a larger role in human evolution than accepted. Carrier explains in the press release:

The debate over whether or not there is a dark side to human nature goes back to the French philosopher Rousseau who argued that before civilization humans were noble savages; that civilization actually corrupted humans and made us more violent. This idea remains strong in the social sciences and in recent decades has been supported by a handful of outspoken evolutionary biologists and anthropologists. Many other evolutionary biologists, however, find evidence that our distant past was not peaceful.

Morgan ultimately believes their research is about human nature and peace: “Our research is about peace,” he said in the press release. “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."