Saturday, April 16, 2022

Analyses from >100 species of birds & mammals revealed robust positive correlations between yawn duration and brain mass and overall & cortical/pallium neuron totals; the observation of yawning in conspecifics selectively enhances vigilance

The causes and consequences of yawning in animal groups. Andrew C.Gallup. Animal Behaviour, Volume 187, May 2022, Pages 209-219. 


• Yawning is a highly conserved neurophysiological adaptation among vertebrates.

• The detection of yawning appears to be biologically important in social species.

• The observation of yawning in conspecifics selectively enhances vigilance.

• Yawn contagion appears to function in promoting motor synchrony in groups.

Yawning is a stereotyped action pattern that is prevalent across vertebrates. While there is growing consensus on the physiological functions of spontaneous yawning in neurovascular circulation and brain cooling, far less is known about how the act of yawning alters the cognition and behaviour of observers. By bridging and synthesizing a wide range of literature, this review attempts to provide a unifying framework for understanding the evolution and elaboration of derived features of yawning in social vertebrates. Recent studies in animal behaviour, psychology and neuroscience now provide evidence that yawns serve as a cue that improves the vigilance of observers, and that contagious yawning functions to synchronize and/or coordinate group activity patterns. These social responses to yawning align with research on the physiological significance of this behaviour, as well as the ubiquitous temporal and contextual variation in yawn frequency across mammals and birds. In addition, these changes in mental processing and behaviour resulting from the detection of yawning in others are consistent with variability in the expression of yawn contagion based on affinity and social status in primates. Topics for further research in these areas are discussed.

Keywords: arousalcircadian rhythmscollective behaviourmotor synchronystate changestressthermoregulationvigilance

Summary and future directions

Yawning is a neurophysiological adaptation that is omnipresent across vertebrates (Massen et al., 2021), and the detection of this action pattern in others appears to be biologically important among social species (Tsurumi et al., 2019). Moreover, recent studies indicate that yawning serves as a cue that enhances individual vigilance and promotes motor synchrony through contagion (see Fig. 1 for a graphic illustration of these processes). However, additional research is needed to replicate and further examine the nature of these effects, as well as investigate potential comparative differences in these responses based by on ecological factors and evolutionary history. In particular, future studies could examine how exposure to yawns alters the detection of threatening stimuli across different species, as well as how experimentally induced yawn contagion influences different patterns of motor synchrony and group coordination among human and nonhuman animals in the laboratory. In addition, naturalistic studies could investigate how the detection of yawning alters scanning rates and vigilance monitoring in free-moving groups, as well as how yawning and other patterns of behavioural contagion influence collective movement across different species. For example, among many species, yawning and stretching tend to co-occur, and both behaviours have been found to be contagious in budgerigars (Gallup et al., 2017Miller, Gallup, Vogel, Vicario, et al., 2012). Since yawn and stretch contagion could have similar functions among animal groups in initiating collective action, future research could assess whether behavioural contagion in general is a key feature in initiating synchrony.

Figure 1Figure 1

The current evidence suggests that yawning serves as a cue rather than as a signal, but future studies could further examine whether spontaneous yawns evolved specifically to communicate internal states and/or alter the behaviour of observers in some species. For example, studies could investigate whether yawning occurs more readily in the presence of others and in contexts in which synchrony and/or vigilance would be most advantageous to the group. In addition, researchers could examine patterns in the variability of yawn expression. A recent study on macaques (Macaca tonkeana and M. fuscata) suggests differences in the morphology and duration of yawning are predictive of the contexts in which this behaviour arises (Zannella et al., 2021), so follow-up studies could also assess how different types of yawns differentially impact the subsequent vigilance behaviour and synchronization of observers. Similarly, researchers could assess differences in yawn-induced changes in behaviour based on the presence or absence of auditory cues. Vocal components to yawning appear to be common among humans and nonprimates (e.g. Massen et al., 2015Palagi et al., 2009), yet seem unnecessary for the physiological function(s) of this action pattern. Thus, studies could investigate the factors that contribute to variation in vocal yawning and how the social outcomes of yawning vary based on visual and/or auditory detection.

Further examination of yawning in animals could provide important insights into the social role of this behaviour and its function in altering group dynamics, which could in turn offer applications for improving performance in surveillance settings and organized group activities in our own species. Based on what is already known about the social nature of yawning, it appears time to systemically examine some of the more overt social features of this behaviour in humans. This includes the stigmatization of yawning in some cultures (Schiller, 2002), which leads to the active concealment (Schino & Aureli, 1989) and/or inhibition of yawning when in the presence of others (Gallup, Church, Miller, et al., 2016Gallup et al., 2019). For example, further research is needed to fully understand and disentangle the potential physiologic and social causes and consequences of inhibiting spontaneous and contagious yawning in groups. In line with the comparative perspective highlighted throughout this review, the bridging of both human and nonhuman animal research will provide the most comprehensive understanding of this evolutionarily conserved behaviour.

Results suggested that people were less ready to commit to a romantic relationship to the extent that they perceived they had many partners available to them

Playing the field or locking down a partner?: Perceptions of available romantic partners and commitment readiness. Ashlyn Brady et al. Journal of Experimental Social Psychology, Volume 101, July 2022, 104334.

Abstract: People often consider how ready they feel for a committed romantic relationship before initiating one. Although research has only begun to identify the antecedents of commitment readiness, several theoretical perspectives suggest that it should be shaped by the perceived frequency of available partners. We conducted five studies (one correlational, four experimental) that tested this idea among single people. A Pilot Study assessed participants' perceptions of available romantic partners and their commitment readiness. In the subsequent four experiments, participants read articles (Studies 1a and 1b) or created dating profiles and were presented with false feedback (Studies 2 and 3) that influenced perceptions of available partners and reported their commitment readiness. Results suggested that people were less ready to commit to a romantic relationship to the extent that they perceived they had many partners available to them. These results further understanding of factors that promote the decision to initiate a committed relationship.

Keywords: Commitment readinessRelationship initiationRomantic relationshipsAvailable partnersCommitment

Women enjoyed higher levels of purpose in life; & were more likely to have altruistic behaviors and attitudes, which in turn facilitated a stronger purpose in life

From 2018... Gender Differences in Purpose in Life: The Mediation Effect of Altruism. Juan Xi et al. Journal of Humanistic Psychology, Jun 7, 2018.

Abstract: A strong meaning or purpose in life, as a key indicator for psychological well-being, has been found to enhance health and longevity in a large amount of empirical research. In this study, we focus on gender differences in purpose in life. Using a large nationally representative sample, we found that women enjoyed higher levels of purpose in life. We further examined the role of altruism in accounting for much of the gender differences in life purpose. Women were more likely to have altruistic behaviors and attitudes, which in turn facilitated a stronger purpose in life. Our study suggests that men could plausibly attain a similar level of purpose in life if social norms encouraged men to nurture the growth of others through altruistic acts to the same extent as women.

Keywords: purpose in life, altruism, gender

The widespread public scepticism about Darwinism in most developed countries can be understood in terms of the counter-intuitive nature of the theory – we experience species as fixed and distinct in kind, not changing and only quantitatively different – and lack of education about the fundamental concepts

Darwinian explanations and socio-cultural processes: A synthesis. Daniel Nettle. Before 2008?

1. The problem

Darwin’s theory of evolution, in particular as it has emerged from the synthesis with Mendelian genetics in the 1930s and the clarification of the levels of selection issue in the 1960s, is the most important – ultimately, the only – deep-level theory in the life sciences. It provides a unification of the various disciplines of biology around a common set of explanatory principles which are demonstrably correct. As the great Theodosius Dobzhansky put it, ‘Nothing in biology makes sense except in the light of evolution’ (Dobzhansky 1973).  The various forms of intellectual critique of Darwinian theory in general - rather than particular local predictions derived from it - collapse under close scrutiny, and their persistence can be attributed to ideological and historical antipathies rather than any scientific substance (see Dennett 1995, Kitcher 2007, for some discussion, and Wilson 2007 for a readable introduction to modern Darwinism). The widespread public scepticism about Darwinism in most developed countries (Miller, Scot & Okamoto 2006) can likewise be understood in terms of the counter-intuitive nature of the theory – we experience species as fixed and distinct in kind, not changing and only quantitatively different – and lack of education about the fundamental concepts, rather than any flaws in the theoretical edifice. The social and human sciences provide an interesting contrast with the rest of the life sciences. For one thing, they lack a unifying theory, and exist as a more or less untranslatable set of local principles used within one discipline or one part of a discipline (Hermann-Pillath 1994, Wilson 1998, Barkow 2006). It is quite common for social science textbooks to present a number of meta-theoretical approaches, usually associated with particular influential individuals, without providing any criteria for adjudicating between them, leading to the impression that paradigmatic issues are a matter of taste rather than truth. Under these conditions, there is a continual splitting of sub-disciplines and problematizing of approaches, along with frequent statements that this or that field is in crisis, and the human sciences languish whilst the biological sciences, bold and theoretically self-confident, occupy ever more of the pages of influential journals.