Of Lion Manes and Human Beards: Some Unusual Effects of the Interaction between Aggression and Sociality

Are Beards Honest Signals of Male Dominance and Testosterone?

The male beard is one of the most visually salient and sexually dimorphic traits and a hypothesized potential marker of other traits, such as dominance, masculinity, social status, and self-confidence. However, as men can easily alter their facial hair, beards may provide unreliable information about the beard owner's characteristics. Here, we examined whether beards are honest signals of biological (testosterone levels) and psychological (self-reported dominance) traits. Young (M = 21.29, SD = 1.54) and healthy men (N = 97) participated in the study. Their beards were measured directly (using digital calipers) and by self-report. Participants provided saliva samples before and after acute exercise (to assess their testosterone and cortisol levels) and reported their dominance on a 5-item scale. The results showed that beard length (directly measured and self-reported) was not related to testosterone levels or dominance; thus, no evidence was found to support the hypothesis that beards are honest (or dishonest) signals of the beard owners' testosterone levels and dominance.

Impact Protection Potential of Mammalian Hair: Testing the Pugilism Hypothesis for the Evolution of Human Facial Hair

Because facial hair is one of the most sexually dimorphic features of humans (Homo sapiens) and is often perceived as an indicator of masculinity and social dominance, human facial hair has been suggested to play a role in male contest competition. Some authors have proposed that the beard may function similar to the long hair of a lion’s mane, serving to protect vital areas like the throat and jaw from lethal attacks. This is consistent with the observation that the mandible, which is superficially covered by the beard, is one of the most commonly fractured facial bones in interpersonal violence. We hypothesized that beards protect the skin and bones of the face when human males fight by absorbing and dispersing the energy of a blunt impact. We tested this hypothesis by measuring impact force and energy absorbed by a fiber epoxy composite, which served as a bone analog, when it was covered with skin that had thick hair (referred to here as “furred”) versus skin with no hair (referred to here as “sheared” and “plucked”). We covered the epoxy composite with segments of skin dissected from domestic sheep (Ovis aries), and used a drop weight impact tester affixed with a load cell to collect force versus time data. Tissue samples were prepared in three conditions: furred (n = 20), plucked (n = 20), and sheared (n = 20). We found that fully furred samples were capable of absorbing more energy than plucked and sheared samples. For example, peak force was 16% greater and total energy absorbed was 37% greater in the furred compared to the plucked samples. These differences were due in part to a longer time frame of force delivery in the furred samples. These data support the hypothesis that human beards protect vulnerable regions of the facial skeleton from damaging strikes.

Sexual Selection, Agonistic Signaling, and the Effect of Beards on Recognition of Men’s Anger Displays

The beard is arguably one of the most obvious signals of masculinity in humans. Almost 150 years ago, Darwin suggested that beards evolved to communicate formidability to other males, but no studies have investigated whether beards enhance recognition of threatening expressions, such as anger. We found that the presence of a beard increased the speed and accuracy with which participants recognized displays of anger but not happiness (Experiment 1, N = 219). This effect was not due to negative evaluations shared by beardedness and anger or to negative stereotypes associated with beardedness, as beards did not facilitate recognition of another negative expression, sadness (Experiment 2, N = 90), and beards increased the rated prosociality of happy faces in addition to the rated masculinity and aggressiveness of angry faces (Experiment 3, N = 445). A computer-based emotion classifier reproduced the influence of beards on emotion recognition (Experiment 4). The results suggest that beards may alter perceived facial structure, facilitating rapid judgments of anger in ways that conform to evolutionary theory.

Rethinking Attachment Theory

Bowlby’s attachment theory has stimulated research covering a variety of topics related to individual and relational well-being, such as courtship, mate selection, motivations, emotional responses, cognitions, dreams, values, and psychopathology. This research has contributed greatly to the understanding of individual differences in mental health but at the same time has gradually lost touch with the original evolutionary essence of attachment theory. In this article, we revisit Bowlby’s original conceptualization and argue that although attachment styles relate to many different aspects of people’s lives, their primary function is to promote survival. Accordingly, we present social-defense theory and illustrate how different attachment orientations work in synergy to promote group survival, such that a social group comprising members with different attachment patterns has clear adaptive advantages over a homogeneous group of securely attached individuals. We therefore challenge the axiomatic view of insecure attachment as a psychological liability, contending that each attachment disposition has specific adaptive advantages. In making this argument, we extend the scope of attachment theory and research by considering a broader range of adaptive functions of insecure attachment strategies, and present data to support our argument.

Facing danger: how do people behave in times of need? The case of adult attachment styles

Bowlby’s (1982) attachment theory has generated an enormous body of research and conceptual elaborations. Although attachment theory and research propose that attachment security provides a person with many adaptive advantages, during all phases of the life cycle, numerous studies indicate that almost half of the human species can be classified as insecurely attached or insecure with respect to attachment. It seems odd that evolution left humans in this vulnerable position, unless there are some advantages to individuals or groups, under at least some conditions, of anxious and avoidant attachment styles. I argue that a social group containing members with different attachment patterns may be more conducive to survival than a homogeneous group of securely attached individuals because each attachment disposition has specific adaptive advantages that promote the survival of the individual and people around him or her when facing threats and perils. In making this argument, I extend the scope of attachment theory and research by considering a broader range of adaptive functions of insecure attachment strategies, and present data to support my argument.

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

The history of science has frequently included a problem-based impetus toward research that can be translated expeditiously into solutions. A current problem is that psychopathologies, typically chronic, contribute hugely to the economic and social burden of medical care, especially in the United States. For behavioral neuroscientists a psychopathology-aimed translational research emphasis particularly involves animal models to facilitate the experimental and invasive work necessary to an understanding of the biology of normal and aberrant behavior. When the etiology of a particular psychopathology is unknown, and there are no specific biomarkers, behavioral parallels between the focal disorder and its putative models become crucial elements in assessing model validity. Evaluation of these parallels is frequently neglected, reflecting in part the lack of a systematic conceptualization of the organization of behavior and how this may be conserved across species. Recent work specifically attempting to bridge this gap suggests that analysis of behaviors that are functional - adaptive in crucial situations such as danger or social contexts - can facilitate an understanding of the parallels between behaviors of human and nonhuman species, including the dysfunctional behaviors of psycho pathologies. As research with animal models comes to provide a more systematic analysis of particular behaviors and their adaptive functions, cross-talk between model and focal psychopathology may be advantageous to understanding both.