Fluffy beards: Safeguard or just for show?

Today, the longest beard measures 17 feet, 6 inches. On average, facial hair grows about a half inch per month. To many, the beard is a common feature of a man — one that is rarely looked at when discussing evolution. What is its purpose? Does a beard have specific uses, or is it just a physical trait used for show?

Puffy facial hair is typically seen as a form of masculinity. Sexual dimorphism gives males this trait, which has been used as male competition over the years of human evolution. The question, however, is whether this is the only or best reason for the facial blanket to be where it is anatomically. Some animal features, such as lion manes, are evidence of sexual dimorphism giving males an identifiable trait as well as an edge in higher competitive territories. However, biologists argue the mane of a lion can also be used as a form of protection from attacks to the lower head and neck. In a biology study done in April 2020, researchers from the University of Utah designed an experiment to test whether this theory proved the same with beards of human men, serving not only as a visual difference between men and women but as a development of protection against hits to the head and neck.

In a biology study done in April 2020, researchers from the University of Utah designed an experiment to test whether this theory proved the same with beards of human men, serving not only as a visual difference between men and women but as a development of protection against hits to the head and neck.

The human mandible, or jawbone, is one of the most fragile bones in the body. It is highly susceptible to fractures and breaks when put under stress due to violence. This knowledge inspired the hypothesis that facial hair was developed to minimize the damage of impacts during violence, which was then tested by a University of Utah research team. In their experiment, a mandible and supporting bones were constructed out of a fiber epoxy composite, which was then attached to sheep skin and fleece. While sheep fleece is not a perfect replica, it was approximated to be about the same thickness and density as follicles of facial hair. Using an anvil and striker, the team tested various levels of beard thickness on the mandible. They record the amount of force intake as well as the time the hit took to reach full impact on the mandible. The results showed a variation of data for each level of sheep fleece thickness, the largest variation being in the time it takes for the full force of the striker to reach the mandible. The greatest advantage of protection to male jaws: the amount of force is widely distributed and not absorbed in the same spot, making the force of the hit less likely to cause substantial amounts of damage to the mandible or other facial bones.

The greatest advantage of protection to male jaws: the amount of force is widely distributed and not absorbed in the same spot, making the force of the hit less likely to cause substantial amounts of damage to the mandible or other facial bones.

Of course, the mane of a lion supplies a larger amount of protection than human facial hair, though they still share many common traits that lead biologists to believe their functions are similar. The sexual dimorphism of manes and beards suggests they evolved to be identifiers of the animal’s sex and to be potential tools used during male competition. In a study done by research biologists at the University of Minnesota in 2005, male lions were found to be more likely to die within a year of receiving an injury to the neck or mane area, while females would typically die within a month after receiving similar injuries. Also, in humans, a 1990 paper by Jonathan Shepherd suggests women make up only 8% to 32% of interpersonal violence, meaning, based on evolution theories, they had less need for facial hair protection.

The flip side argues that violence between males is becoming less about environmental competition. For lions, nearly all interpersonal violence between males is a result of male competition for mating, so some argue there is no connection between the two traits. Similarly, some may be skeptical about the data done in the experiment by the University of Utah researchers, as it was done with sheep products and an epoxy composite, rather than true human anatomy. Either way, when arguing the hypothesis that facial hair was developed as a form of protection against violence, it’s hard to argue the findings that it aids in the distribution of forces from violence on top of being a dimorphic trait for show.

Image courtesy of Wikimedia Commons