Men have evolved to grow beards in order to protect their jaws from incoming punches from foes, a study has found.
Facial hair is the most evident manifestation of sexual dimorphism — physical differences between males and females — in humans.
But its actual purpose has long remained an enigma, with some researchers claiming its purpose is to appeal to women and enhance their sexual attractiveness.
However, a new study has found the main benefit of a beard is to soften the impact of a punch.
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Facial hair is the most evident manifestation of sexual dimorphism — physical differences between males and females — in humans. But its actual purpose has long remained an enigma (stock)
University of Utah researchers set out to see if they could prove a beard was good at softening blows sustained in a melee.
They created analogues of the human jaw made from epoxy resin and covered it in sheep skin covered in various levels of fur: hairless, trimmed and a full-blown beard.
Skin was kept moist to simulate real skin while the fur, which imitates the beard, was kept dry during the experiments.
Researchers produced 20 of each type and then dropped a 10.3lbs (4.7 kg) metal weight onto the skin which was fixed to an anvil.
Writing in their study, the scientists say the experiment would be improved if they could use actual human skin with facial hair still in place, however admit it ‘was not practical’.
As the weight fell on the imitation human chin a machine detected how much force went through the bone and how much was absorbed.
‘We found that fully furred samples were capable of absorbing more energy than plucked and sheared samples,’ the researchers write in their study published in the journal Integrative Organismal Biology.
‘For example, peak force was 16 per cent greater and total energy absorbed was 37 per cent greater in the furred compared to the plucked samples.’
The energy of an impact, whether from a falling weight on an anvil or a well-aimed uppercut, is spread out by the bushy facial hair
The scientists add: ‘The results of this study indicate that hair is indeed capable of significantly reducing the force of impact from a blunt strike and absorbing energy, thereby reducing the incidence of failure.’
‘If the same is true for human facial hair, then having a full beard may help protect vulnerable regions of the facial skeleton from damaging strikes, such as the jaw.
‘Presumably, full beards also reduce injury, laceration, and contusion, to the skin and muscle of the face.’
A study published earlier this year from the same team of researchers in Utah also found further evidence that male bodies evolved with a focus on hand-to-hand combat, and besting another man in a fistfight.
A new study has found the main benefit of a beard is to soften the impact of a punch. The researchers found that having a beard absorbed 37 per cent more energy from a punch compared to a shaved face (stock)
This study revealed that men throughout all of time have been forced to scrap in order to win the affections of women and have children.
This pressure has caused male bodies to change, becoming more powerful and explosive when throwing a punch.
Over thousands of years, men unable to fight were slowly weeded out of the gene pool and, as a result, modern males are accomplished at hand-to-hand conflict.
The end result is that male bodies became specifically tailored by evolution to be good at punching.
For example, researchers in the US found that the weakest man punches harder than than the strongest woman in tests.
Researchers write in the study: ‘Sexual dimorphism often arises from selection on specific musculoskeletal traits that improve male fighting performance.
‘In humans, one common form of fighting includes using the fists as weapons.’
Men’s average power during a punching motion test was 162 per cent greater than females, they found.
However when it came to spear throwing, the difference was not as great, implying evolution built men to fight, not to hunt.
Professor David Carrier at the University of Utah said: ‘This is a dramatic example of sexual dimorphism that’s consistent with males becoming more specialised for fighting and males fighting in a particular way, which is throwing punches.
‘There are two sides to who we are as a species.
‘If our goal is to minimise all forms of violence in the future, then understanding our tendencies and what our nature really is, is going to help.’