Of lion manes and human beards: some unusual effects of the interaction between aggression and sociality

Abstract

The function of manes in lions has been a topic of scientific interest since Darwin (1871) suggested that it provides protection in intraspecific fights. Recent experimental studies on wild lions have emphasized the role of female selection, but analyses of specific attack behaviors and targets, and the social consequences of manelessness for lions living in very hot climates suggest that male manes may indeed mitigate the outcomes of intraspecific male attack and thus serve a permissive function for multi-male + female groups, facilitating protection of prides against take-overs and infanticide by nomadic males. Humans also have unusual structural protections for the head, face and neck, areas that are especially accessible during intraspecies attack, and highly vulnerable to damage. One of these, the beard, consists of coarse hairs that grow indefinitely, but only for males, and only during and following puberty; suggesting that it, like the lion's mane, may serve as protection in intraspecies male fights. Such structural protections may reflect a specific combination of lethal weaponry and social life-style, particularly when these are developed so rapidly that they are not accompanied by the evolution of complex attack-inhibiting social behaviors.

Contest competition and men's facial hair: beards may not provide advantages in combat

“…In MMA, the majority of serious injuries occur on the face, particularly the jaw and cheek bones (Lystad et al, 2014), which are the regions where beard growth is most profuse . Blanchard (2009) suggested that the human beard functions like the mane of the male lion in providing protection to the face and neck during fights. We found no evidence that bearded fighters succumb to fewer knockouts than clean-shaven fighters and therefore conclude that facial hair does not provide any protective advantage during male-male contest competition.…”

“…The UFC provides a unique opportunity to test whether beards provide any advantage to fighters or reflect a fighter's performance. While most sports that involve fights, including groups that sanction boxing and wrestling, restrict the growth of facial hair owing to views that it enhances protection against blows (Blanchard, 2009), this restriction does not apply in the UFC. Although beards cannot enhance fighting ability directly, there are two main hypotheses that suggest evolutionary advantages for facial hair during intra-sexual contests.…”

“…First, phylogenetic analyses of the facial structures of ancestral members of the genus Homo suggest that facial structure and musculature evolved, in part, to protect against blows to the head (Carrier & Morgan, 2015). As facial hair develops around the around the jaw, lips and midface, framing and enhancing perceptions of the sexually dimorphic facial regions (Guthrie, 1970), Blanchard (2009) hypothesised that beards are analogous to the male lion's mane in covering the vital parts of the face and neck from costly strikes. Since meta-analyses of MMA bouts revealed that 66-78% of serious injuries are to the head and face (Jensen et al, 2017;Lystad et al, 2014), if the human beard has evolved as a protective organ to blows to the lower face (Blanchard, 2009), then fighters with beards should suffer fewer knockouts and technical knockouts than cleanshaven fighters.…”

The African Lion: A Long History of Interdisciplinary Research

“…The dark-maned males enjoyed greater survival and reproductive success; thus, the lion's mane appears to be an honest indicator of being able to take the heat, rather than as a shield to protect the head and neck against wounding (West et al, 2006). Amusingly, our work inspired several investigations into the function of the male beard in humans (Blanchard, 2010;Dixson and Vasey, 2012).…”

The role of behavior in translational models for psychopathology: Functionality and dysfunctional behaviors

“…Blanchard, 2010; Estes, 1991). However, the laboratory-based study of sociality and species-typical social patterns has generally lagged behind that of more easily manipulated systems such as defense, ingestion, or sexual behavior.…”