The Role of Violence in Evolution

From evolutionary biology comes a new study that suggests the shape of our face is actually a result of violence in our prehistoric ancestors.  Researchers from the latest study say that human faces evolved to minimize the impact of injury from punches to the face.  The team, led by biologist David Carrier and physician Michael H Morgan, focused on our australopith ancestors.  These are human-like primates who lives in Africa between 6 and 1.2 million years ago, and strongly resemble the modern-day chimpanzee.  Australopiths had a mix of both human and ape traits, walked on two legs, had small brains and small canine teeth, although their cheek teeth were quite large.


An artist’s renditioning of the Australopith.

The most widely-known example of an australopith is “Lucy”, a well-preserved fossilized skeleton from Ethiopia that dates to about 1.2 million years ago.  Previously, the most prominent hypothesis held that the evolution of our ancestors’ faces was a need to chew foods that were difficult to crush, such as nuts.  However, Carrier says that australopiths had traits that could have boosted fighting ability, such as hand proportions that allowed them to make a fist, which is effective for striking others.  If indeed the evolution of our hand proportions were associated with selection for fighting behavior, then you might expect the primary target, the face, to have undergone evolution to better protect it from injury.  Even nowadays, when humans fight with their hands, they typically aim for the face.

What Carrier and his team 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.  He further explains that such bones are part of the skull that exhibits the biggest difference between both australopith and human men and women.  In other words, male and female faces are different because the parts of the skull that break in fights are bigger in males.  Most importantly, however, he notes that such facial features are found in the fossil record around the same time that our ancestors developed the hand proportions that allowed them to make a fist.  The observations suggest that many of the facial features that characterize early hominins may have evolved to protect the face from injury during fistfights.

The team added that their study adds to the continuing conversation about the role that violence played in our evolution, and their work suggests that violence played a much larger role in human evolution than many anthropologists accept.  Morgan believes that the science behind this is strong, and fills some longstanding gaps in the existing theories as to why the musculoskeletal structures of our faces developed the way that they did.  Such research into the evolution of our human ancestors is relevant, as it provides insight into how and why we evolved into what we are now.  Carrier says that the new research not only provides a different reason for the evolution of our faces, but also addresses the controversial question of how much a role violence played in the early days of our ancestors.  This question goes back to the French Enlightenment philosopher Rousseau, who argued that before civilization corrupted mankind, our ancestors were “noble savages”, an idea that remained strong in social sciences.