On the function of facial muscles in different behavioral situations. A study based on muscle morphology and electromyography

The anatomy and function of the facial muscles of Macaca cyclopis, M. fuscata, M. irus, M. mulatta, and M. nemestrina have been correlated and analyzed by means of electromyograms made by a 12-channel electromyograph. We made records only of those areas where there is one layer of facial muscles. Morphologically the muscular differences among the species are insignificant for the recording of EMGs. Functionally, the facial muscles moving the eyebrows and ears differ under certain conditions. There is no muscle activity during sleep: during dozing, only a slight lowering of the eyebrows was noted and sometimes an extremely low level of watching behavior. The ear and eyebrow movements during the watching responses differ among the species. The basis for threatening behavior is watching: but most species raise the ears and eyebrows more extremely in threat, and other muscle activities differ among the species. In all species, the facial muscles are contracted in fear to a greater or lesser degree. Some muscular responses, too brief to be detected by observers but recorded by the EMG, can thus be analyzed and compared with the expressions of observed behavior.     

Early cortical specialization for face-to-face communication in human infants

This study examined the brain bases of early human social cognitive abilities. Specifically, we investigated whether cortical regions implicated in adults' perception of facial communication signals are functionally active in early human development. Four-month-old infants watched two kinds of dynamic scenarios in which a face either established mutual gaze or averted its gaze, both of which were followed by an eyebrow raise with accompanying smile. Haemodynamic responses were measured by near-infrared spectroscopy, permitting spatial localization of brain activation (experiment 1), and gamma-band oscillatory brain activity was analysed from electroencephalography to provide temporal information about the underlying cortical processes (experiment 2). The results revealed that perceiving facial communication signals activates areas in the infant temporal and prefrontal cortex that correspond to the brain regions implicated in these processes in adults. In addition, mutual gaze itself, and the eyebrow raise with accompanying smile in the context of mutual gaze, produce similar cortical activations. This pattern of results suggests an early specialization of the cortical network involved in the perception of facial communication cues, which is essential for infants' interactions with, and learning from, others.     

Browplasty and browpexy: an adjunct to blepharoplasty

Surgical approaches to the eyelids and eyebrows have been refined by application of their anatomy and appreciation of their pathophysiology. Sexual variations in eyebrow appearance can be attributed in part to the eyebrow fat pad. In females, the eyebrow is generally arched and above the level of the supraorbital rim. The male eyebrow is flatter and at the level of the supraorbital rim. The eyebrow fat pad is more prominent in the male, producing a fuller appearance in the lateral brow area. Many women are concerned about the flatter, full lateral brow, which assumes a masculine quality. The authors describe a surgical technique that permits identification of the brow fat pad and then the ability to debulk the eyebrow (browplasty). In addition, the brow can be elevated by internal plication suture to physically elevate the eyebrow (browpexy). This procedure is designed to utilize an eyelid crease incision, and it reduces the indications for more involved procedures to eliminate brow ptosis, such as midforehead or coronal approaches.     

Social smiling in normal and down syndrome infants: A comparative study

The aim of this work has been to compare social smiling in Down syndrome (mongolism) and normal infants, attending especially to the brow movements that appear before it. Facial responses of eight Down syndrome and eight normal infants from three to five months were analized by means of an anatomically based measurement technique during face-to-face interactions with their mothers. Despite their mental retardation, Down syndrome infants showed identical muscle movements as normal infants before and during smiling. However, some differences were found in smile frequency and leght, as well as in the brow movements frequency before smiling. Results are discussed in terms of the psychophisiological dysfunction of Down syndrome infants that are originated by a chromosome imbalance.     

Cultural differences in preferences for facial coloration

Effects of facial coloration on facial attractiveness judgments are hypothesized to be “universal” (i.e., similar across cultures). Cross-cultural similarity in facial color preferences is a critical piece of evidence for this hypothesis. However, only two studies have directly compared facial color preferences in two cultures. Both of those studies reported that White UK and Black African participants showed similar preferences for facial coloration. By contrast with the cross-cultural similarity reported in those studies, here we show cultural differences in the effects of facial coloration on Chinese and White UK participants' facial attractiveness judgments. While Chinese participants preferred faces with decreased yellowness to faces with increased yellowness, White UK participants preferred faces with increased yellowness to faces with decreased yellowness. Chinese participants also demonstrated weaker preferences for facial redness and stronger preferences for facial lightness than did White UK participants. These results suggest that preferences for facial coloration are not universal.     

Subperiosteal brow lifts without fixation

Most surgeons today advocate an endoscopic subperiosteal brow lift for surgical correction of the upper third of the face. At the author's clinic, this operation has been performed since 1994 and the subgaleal bicoronal brow lift is no longer used. In earlier investigations, the author showed that the subperiosteal approach (n = 60) gives a better result than the subgaleal method (n = 60) when compared 1 year after surgery. In the literature, however, there are no published data regarding the long-term results of subperiosteal brow lifts. The author took material from his earlier investigations and looked at the same patients 5 years postoperatively. He compared the subperiosteal approach (n = 30) with the subgaleal brow lift (n = 15) and found that after 5 years the brows of the subgaleal patients were on the same level as they were before surgery, but in the group of subperiosteal brow lifts, almost all of the brows were higher 5 years after surgery than they were 1 year after surgery, with a mean increase in height of 2.5 mm. These findings led the author to the question whether scalp fixation was necessary at all when performing a subperiosteal brow lift. He performed 20 subperiosteal endoscopic brow lifts where scalp fixation was not used at all, relying only on changing the balance of muscle vectors around the eyebrows. Using a computerized instrument, measurements were made of the distance between the medial canthus and the top of the eyebrow, the midpupil and the top of the eyebrow, and the lateral canthus and the top of the eyebrow. All patients were measured before and 1 year after surgery. The author found an increase of the vertical height from the midpupil to the top of the brow, with an average increase of 3.9 mm. There were no differences between patients who had only a brow lift and those who had a brow lift and an upper blepharoplasty at the same time. The author concludes that for most cases where an increased vertical height of the brows of more than 4 mm is not needed, it is not necessary to use scalp fixation to achieve a natural result.     

Correction of lateral brow ptosis: a nonendoscopic subgaleal approach

The authors present their experience with a relatively uncomplicated, rapid technique for elevation of the lateral eyebrow and a simultaneous correction of eyelid hooding that is secondary to the descent of the eyebrow. The procedure is designed for all patients requiring lateral brow elevation, either separately or in combination with other procedures. The authors describe and illustrate their technique.     

The brow slide: a technique for the aesthetic treatment of eyebrow tumors.

Skin neoplasms involving the eyebrow are not an uncommon problem. Standard surgical resections that depend on elliptical excision and closure tend to either remove an excessive amount of brow or place scars in an unfavorable position. We present a simple technique that allows for maximal brow preservation, alignment of remaining brow, and a minimal amount of exposed scars.     

Criteria of facial attractiveness in five populations

The theory of sexual selection suggests several possible explanations for the development of standards of physical attractiveness in humans. Asymmetry and departures from average proportions may be markers of the breakdown of developmental stability. Supernormal traits may present age- and sex-typical features in exaggerated form. Evidence from social psychology suggests that both average proportions and (in females) “neotenous” facial traits are indeed more attractive. Using facial photographs from three populations (United States, Brazil, Paraguayan Indians), rated by members of the same three populations, plus Russians and Venezuelan Indians, we show that age, average features, and (in females) feminine/neotenous features all play a role in facial attractiveness.     

Do facial gestures,visibility or speed of movement influence gaze following responses in pigtail macaques?

This study investigated whether a human model’s facial gestures, speed of head turn and visibility of face influenced gaze-following responses (GFR) in pigtail macaques. A human provided gaze cues by turning her head 90° in one of four directions. Head turns were immediately followed by a facial movement (pucker, eyebrow raise, tongue protrusion, neutral), or were executed swiftly (< 0.5 s), slowly (3 s) or whilst facing away from the monkeys. All monkeys reliably followed the gaze in all conditions with no differences between conditions. A greater frequency of GFR was found in females compared to males, and two hypotheses for this finding are discussed.     

Relationships in six groups of rhesus monkeys II. Dyads

Dyadic relationships are described for rhesus monkeys living in six groups. The kinds, frequencies, directionality, and overall patterning of interactions are examined over a twelve-month period for adult males, adult females, and young monkeys. Kinship, sex, age, reproductive conditions, time, events, and other social relations all affected dyadic relationship. Certain patterns of interactions characterized different relationships, such as those termed “special,” “tense,” “affiliative,” “conflicting.” A component approach is recommended for the understanding of relationships based on an appraisal of attraction, familiarity, and deference between individuals. The importance of assessing relationships in the group context is stressed.     

The vermiculate surface pattern in brow ridges of Australopithecines and other very ancient hominids

A convoluted surface pattern of fine ridges, pits, and grooves characterized the brow ridges of Australopithecines and other very ancient fossil hominids. This vermiculate configuration terminated rather abruptly just below the fronto-zygomatic suture in Australopithecines. It was resistant to oriented cracking from weathering or fractures, contrasting with the smooth but structurally oriented zygomatic bone adjacent to it. The pattern apparently developed as individuals matured. The vermiculate pattern seems to have been a feature of brow surface in hominids through much of their identifiable history, despite substantial changes in shape and size of the supraorbital region during human evolution. Limitations on the area of vermiculate surface in Australopithecines suggest that the pattern was associated in some yet undetermined manner with overlying soft tissues. This gives evidence on the cause and functional significance of the vermiculate pattern in Neandertal and modern crania. Problems of describing surfaces as “vermiculate” are raised by observation of elaborations of surface relief on two individuals.     

The many facets of facial interactions in mammals

Facial interactions are prominent behaviors in primates. Primate facial signaling, which includes the expression of emotions, mimicking of facial movements, and gaze interactions, is visually dominated. Correspondingly, in primate brains an elaborate network of face processing areas exists within visual cortex. But other mammals also communicate through facial interactions using additional sensory modalities. In rodents, multisensory facial interactions are involved in aggressive behaviors and social transmission of food preferences. The eusocial naked mole-rat, whose face is dominated by prominent incisors, uses facial aggression to enforce reproductive suppression. In burrow-living mammals like the naked mole-rat in particular, and in rodents in general, somatosensory face representations in cortex are enlarged. Diversity of sensory domains mediating facial communication might belie underlying common mechanisms. As a case in point, neurogenetics has revealed strongly heritable traits in face processing and identified gene defects that disrupt facial interactions both in humans and rodents.     

Expanding the labor theory of value

This paper revisits debates over the labor theory of value in the 1970s and 1980s and proposes an expansion and revision for the neoliberal era. It draws on three empirical cases of social movements grappling with contemporary changes in the societal division of labor and argues that they can best be understood as “revaluation” projects seeking to bring recognition to aspects of the economy that are necessary for its long-term sustainability but are not “counted” as important.     

Moving in the beat of seconds: Analysis of the time structure of human action

An intercultural comparison in three nonindustrialized cultures (Yanomami. Himba, and Trobriander) investigated the duration of small units of movement patterns in working processes and movements of the hand to the body. Analysis of 1542 of such action units showed that 93% have a duration of 2 to 3 seconds. No difference was to be seen in this respect between the three cultures nor between the two kinds of actions. A significant difference showed up, however, between rhythmically repeated movement patterns and not repeated ones. The first are longer, near to three seconds, and thus make maximal use of the “window of the present” postulated by Pöppel.     

Relationship quality affects fission decisions in wild spider monkeys (Ateles geoffroyi)

Fission–fusion dynamics are thought to be mainly a response to differential availability of food resources. However, social factors may also play a role. Here, we examined whether the quality of social relationships between group members affects fission decisions. During 21 months, we collected data on social interactions and fission events of 22 spider monkeys (Ateles geoffroyi) living in a community in the protected area of Otoch Ma'ax Yetel Kooh, Yucatan, Mexico. By entering seven indexes of social interactions into a principal component analysis, we obtained three components of relationship quality, which we labelled “compatibility,” “value” and “insecurity” given the relative loadings of the indexes. Our results showed that individuals were more likely to fission into the same subgroup with community members with whom they shared higher levels of compatibility and value and lower levels of insecurity. In addition, individuals preferred to fission into the same subgroup with same‐sex group members, as expected based on what is known for the species. Our findings highlight the role of social factors in fission decisions. Adjustments in subgroup size are based on multifaceted social preferences, incorporating previously unexamined aspects of relationship quality, which are independent from overall levels of affiliative interactions.     

Two shades of boldness: novel object and anti-predator behavior reflect different personality dimensions in domestic rabbits

It is increasingly common to quantify and describe behavioral variation in domestic and wild animals in terms of “personality”. Correlating behavioral traits are referred to as personality “dimensions” or “factors” and different dimensions have been reported in different species. “Boldness” is a well-described personality dimension in several species, although some issues remain unclear. Previous models of boldness include both novelty and risk taking, but recent studies indicate that these types of behaviors may reflect separate personality dimensions. In this study, we developed a behavioral test battery for domestic rabbits, and recorded behaviors of 61 individuals in four different situations (novel object, novel arena, social, and predator interactions). We used domestic rabbits as a model because behavioral variation in rabbits has rarely been quantified in terms of personality dimensions, although rabbit behavior is described. We also wanted to investigate behavioral variation in a Swedish rabbit breed of conservation concern — the Gotland rabbit. Factor analysis of the behavioral test measures suggested three personality dimensions: “exploration”, “boldness”, and “anxiety”. Novel object scores clustered in the exploration and boldness factors, whereas scores associated with predator interactions were explained by “anxiety”, indicating that novel object and anti-predator behavior reflect different personality dimensions in rabbits.     

Response entrainment of movement fibers in the optic tract of crayfish

The response properties of jittery movement fibers (JMF) in the crayfish optic tract reacting to a non-moving temporally patterned light were analyzed. The JMFs usually show no response during the regular flickering of stationary light with a flash duration of less than 50 msec when the stimulus frequency is between 4 and 20 per second; however they do respond when the flickering stops if a certain number of flashes have been given. The response appears about 50 msec after the first missing flash, i.e., the latency of the response after the last flash of the train changed from 100 to 300 msec. Thus, the “off” response at the end of the flicker is entrained to the stimulus repetition interval and locked onto the time of the first missing flash. The response of a sustaining fiber to an identical stimulus has quite different features as illustrated in Fig. 2. Some of the fibers show responses to the beginning part of the flicker but not necessarily to each flash, and habituate after several flashes. When a single flash longer than 250 msec is given, the fiber shows an “off” response with about 50 msec latency, as it does to sustained light. Some fibers show a double burst of “off” discharge to single flashes; the first at 50 msec is followed after 120 msec by the second one. However, when the flash duration is between 250 and 50 msec, a single flash elicits little or no response. The latency of the “off” response is as much as 300 msec for short single flashes less than 50 msec. An “on” response to flashes of light is observed when the inter-stimulus interval is more than 5 sec. The responses to the beginning part of flicker train are not simply locked to the just preceding flash except the “on” response to the very first one, but they can be the long latency responses to the flash before that. This response is modified in latency by the succeeding flashes in flicker trains and becomes entrained to the missing flash. Four types of entrainment are classified on the basis of the change in latency from the missing flash with regard to the number of flashes in a train. In most cases, 10 flashes are sufficient to entrain the response to the first missing flash. Non-resposiveness, i.e., habituation, during a regular flicker, may be due to an active inhibitory process, initiated by each succeeding light pulse. The response to the missing flash, therefore results from a disinhibited modified response to the last flash. Some JMFs continue to respond to the flicker even after a considerable number of flashes but only when the repetition interval is about 120 msec corresponding well to the interval of the double burst “off” discharge, thus the JMF has a resonant frequency of about 8 Hz. The JMFs appear to be acting as an irregularity detector in temporal sequence.     

Thinking in continua: beyond the “adaptive radiation” metaphor

“Adaptive radiation” is an evocative metaphor for explosive evolutionary divergence, which for over 100 years has given a powerful heuristic to countless scientists working on all types of organisms at all phylogenetic levels. However, success has come at the price of making “adaptive radiation” so vague that it can no longer reflect the detailed results yielded by powerful new phylogeny‐based techniques that quantify continuous adaptive radiation variables such as speciation rate, phylogenetic tree shape, and morphological diversity. Attempts to shoehorn the results of these techniques into categorical “adaptive radiation: yes/no” schemes lead to reification, in which arbitrary quantitative thresholds are regarded as real. Our account of the life cycle of metaphors in science suggests that it is time to exchange the spent metaphor for new concepts that better represent the full range of diversity, disparity, and speciation rate across all of life.