A thick beard appeared in men, probably to protect the lower jaw from fractures, and write in Integrative Organismal Biology. This is indicated by the results of experiments on models of the jaws with the hair on them. Samples with artificial beard 30 percent more efficiently absorb the energy of impact with a blunt object. Perhaps the presence of dense vegetation on the person in ancient times was an advantage in fights, including social status, due to which the prevalence of thick beards men grew.
In humans, compared with many other mammals, are not very strongly expressed sexual dimorphism — the difference in appearance of male and female individuals. However, it has a place, and one of its most visible manifestations — the density of hair on the face. In women, the normal there are almost none, while almost all the men they grow up. Bearded sometimes seem more powerful, aggressive and masculine compared to shaved.
In addition, the hair on the face of the person located about the same place where the mane of the lion, and could perform the same function — protection from damage during fights. In aggressive encounters men usually labeled the enemy in the head and lower jaw where a beard, often break. Probably, the presence of a beard greatly softens the blows, and in the past, when interpersonal conflicts are often resolved by the use of physical force, not by negotiations, the presence of facial hair can increase the chances of male survival and ultimately increase his status in the group.
The assumption of a protective role of the beard checked by the researchers from the University of Utah led by David Carriera (David R. Carrier). They planned to conduct experiments with these fragments of the lower jaw, obtained from corpses, but did not gain enough samples whose skin would be evenly and completely covered with hair. Therefore, scientists have created models of the jaws made of fiberglass and glued them to the pieces of sheepskin.
On some skins wool (its length was approximately 8 cm) was left untouched, others have trimmed it, leaving only half a centimeter, on the third plucked. Although the hair on the sheep skin are much tighter than in the skin of a human face (6000 follicles per square centimeter compared to 70), human follicles deeper into the skin, and due to this the volume occupied by hair, beard and unshorn fleeces about the same.