The nature and function of human nonverbal vocalisations

Though human nonverbal vocalisations are widespread, scientific consideration of their mechanisms and communicative functions has been largely overlooked. This is despite their close alignment with the vocal communicative systems of primates and other mammals, whose primary function is to signal indexical information relevant to sexual and natural selection processes. In this thesis, I examine human nonverbal vocalisations from an evolutionary perspective, with the central hypothesis that they are functionally and structurally homologous to nonhuman mammal calls, communicating evolutionarily relevant indexical information that is perceived and utilised by listeners. In Chapter 1, I introduce the methodological framework (source-filter theory) necessary to understand the production of vocal signals in mammals, before summarising the information contained within the acoustic structure of nonhuman mammals and human speech, and the effects these cues have on both vocaliser and listener. I then examine the current evidence for functional and structural homology between human and nonhuman nonverbal vocalisations. In Chapters 2 to 5, I quantitatively analyse the acoustic structure of a number of nonverbal vocalisations, and perform playback experiments to examine their functional effects on listeners. In Chapters 2 and 3, I investigate whether aggressive roars and distress screams communicate acoustic cues to absolute and relative strength and height. In Chapter 4, I analyse the acoustic structure of pain cries of varying intensity, and conduct playback experiments to explore the acoustic and perceptual correlates of pain. In Chapter 5, I examine whether the fundamental frequency of tennis grunts produced during professional tennis matches is dependent on the sex and body posture of the vocaliser, as well as the progress and outcome of the contest, and whether listeners can infer these cues. In Chapter 6, I tie these findings together, arguing that the acoustic structure of human nonverbal vocalisations, in continuity with nonhuman mammal vocalisations, has been selected to support the functional communication of indexical and motivational information

Vocal communication of simulated pain

While evidence suggests that pain cries produced by human babies and other mammal infants communicate acoustic cues to pain intensity, whether the pain vocalisations of human adults also encode pain intensity, and which acoustic characteristics influence listeners’ perceptions, remains unexplored. Here, we investigated how trained actors communicated pain by comparing the acoustic characteristics of nonverbal vocalisations expressing different levels of pain intensity (mild, moderate, and severe). We then performed playback experiments to examine whether vocalisers successfully communicated pain intensity to listeners, and which acoustic characteristics were responsible for variation in pain ratings. We found that the mean and range of voice fundamental frequency (F0, perceived as pitch), the amplitude of the vocalisation, the degree of periodicity of the vocalisation, and the proportion of the signal displaying nonlinear phenomena all increased with the level of simulated pain intensity. In turn, these parameters predicted increases in listeners’ ratings of pain intensity. We also found that while different voice features contributed to increases in pain ratings within each level of expressed pain, a combination of these features explained an impressive amount of the variance in listeners’ pain ratings, both across (76%) and within (31-54%) pain levels. Our results show that adult vocalisers can volitionally simulate and modulate pain vocalisations to influence listeners’ perceptions of pain in a manner consistent with authentic human infant and nonhuman mammal pain vocalisations, and highlight potential for the development of a practical quantitative tool to improve pain assessment in populations unable to self-report their subjective pain experience

Human roars communicate upper-body strength more effectively than do screams or aggressive and distressed speech

Despite widespread evidence that nonverbal components of human speech (e.g., voice pitch) communicate information about physical attributes of vocalizers and that listeners can judge traits such as strength and body size from speech, few studies have examined the communicative functions of human nonverbal vocalizations (such as roars, screams, grunts and laughs). Critically, no previous study has yet to examine the acoustic correlates of strength in nonverbal vocalisations, including roars, nor identified reliable vocal cues to strength in human speech. In addition to being less acoustically constrained than articulated speech, agonistic nonverbal vocalizations function primarily to express motivation and emotion, such as threat, and may therefore communicate strength and body size more effectively than speech. Here, we investigated acoustic cues to strength and size in roars compared to screams and speech sentences produced in both aggressive and distress contexts. Using playback experiments, we then tested whether listeners can reliably infer a vocalizer’s actual strength and height from roars, screams, and valenced speech equivalents, and which acoustic features predicted listeners’ judgments. While there were no consistent acoustic cues to strength in any vocal stimuli, listeners accurately judged inter-individual differences in strength, and did so most effectively from aggressive voice stimuli (roars and aggressive speech). In addition, listeners more accurately judged strength from roars than from aggressive speech. In contrast, listeners’ judgments of height were most accurate for speech stimuli. These results support the prediction that vocalizers maximize impressions of physical strength in aggressive compared to distress contexts, and that inter-individual variation in strength may only be honestly communicated in vocalizations that function to communicate threat, particularly roars. Thus, in continuity with nonhuman mammals, the acoustic structure of human aggressive roars may have been selected to communicate, and to some extent exaggerate, functional cues to physical formidability

Human listeners can accurately judge strength and height relative to self from aggressive roars and speech

While animal vocalisations and human speech are known to communicate physical formidability, no previous study has examined whether human listeners can assess the strength or body size of vocalisers relative to their own, either from speech or from nonverbal vocalisations. Here, although men tended to underestimate women’s formidability, and women to overestimate men’s, listeners judged relative strength and height from aggressive roars and aggressive speech accurately. For example, when judging roars, male listeners accurately identified vocalisers who were substantially stronger than themselves in 88% of trials, and never as weaker. For male vocalisers only, roars functioned to exaggerate the expression of threat compared to aggressive speech, as men were rated as relatively stronger when producing roars. These results indicate that, like other mammals, the acoustic structure of human aggressive vocal signals (and in particular nonverbal roars) may have been selected to communicate functional information relevant to listeners’ survival

“To dispose of wealth in works of charity”: entrepreneurship and philanthropy in Medieval England

While entrepreneurs are increasingly recognized as important participants in the medieval economy, their philanthropic activities have received less attention compared to those of the gentry and nobility. This article shows the contribution that the study of medieval entrepreneurs can make to broader business history debates surrounding the identity of philanthropists and their beneficiaries, the types of causes they supported, and their impact on wider society. Philanthropic entrepreneurs used the profits of commerce to provide infrastructure, healthcare, and education to their local communities. Their patterns of philanthropy differed from those of gentry, lawyers, and administrators. Support for municipal infrastructure emerges as a distinctive feature of entrepreneurial philanthropy, reflecting a belief in the importance of trade networks and civic reputation

Effects of habitat composition and landscape structure on worker foraging distances of five bumblebee species

Bumblebees (Bombus spp.) are important pollinators of both crops and wild flowers. Their contribution to this essential ecosystem service has been threatened over recent decades by changes in land use, which have led to declines in their populations. In order to design effective conservation measures it is important to understand the effects of variation in landscape composition and structure on the foraging activities of worker bumblebees. This is because the viability of individual colonies is likely to be affected by the trade-off between the energetic costs of foraging over greater distances and the potential gains from access to additional resources. We used field surveys, molecular genetics and fine resolution remote sensing to estimate the locations of wild bumblebee nests and to infer foraging distances across a 20 km2 agricultural landscape in southern England. We investigated five species, including the rare B. ruderatus and ecologically similar but widespread B. hortorum. We compared worker foraging distances between species and examined how variation in landscape composition and structure affected foraging distances at the colony level. Mean worker foraging distances differed significantly between species. Bombus terrestris, B. lapidarius and B. ruderatus exhibited significantly greater mean foraging distances (551 m, 536 m, 501 m, respectively) than B. hortorum and B. pascuorum (336 m, 272 m, respectively). There was wide variation in worker foraging distances between colonies of the same species, which was in turn strongly influenced by the amount and spatial configuration of available foraging habitats. Shorter foraging distances were found for colonies where the local landscape had high coverage and low fragmentation of semi-natural vegetation, including managed agri-environmental field margins. The strength of relationships between different landscape variables and foraging distance varied between species, for example the strongest relationship for B. ruderatus being with floral cover of preferred forage plants. Our findings suggest that favourable landscape composition and configuration has the potential to minimise foraging distances across a range of bumblebee species. There is thus potential for improvements in the design and implementation of landscape management options, such as agri-environment schemes, aimed at providing foraging habitat for bumblebees and enhancing crop pollination services

Physical activity for cognitive and mental health in youth: A systematic review of mechanisms

Context: Physical activity can improve cognitive and mental health, but the underlying mechanisms have not been established. Objective: To present a conceptual model explaining the mechanisms for the effect of physical activity on cognitive and mental health in young people and to conduct a systematic review of the evidence. Data Sources: Six electronic databases (PubMed, PsycINFO, SCOPUS, Ovid Medline, SportDiscus, and Embase) were used. Study Selection: School-, home-, or community-based physical activity intervention or laboratory-based exercise interventions were assessed. Studies were eligible if they reported statistical analyses of changes in the following: (1) cognition or mental health; and (2) neurobiological, psychosocial, and behavioral mechanisms. Data Extraction: Data relating to methods, assessment period, participant characteristics, intervention type, setting, and facilitator/delivery were extracted. Results: Twenty-five articles reporting results from 22 studies were included. Mechanisms studied were neurobiological (6 studies), psychosocial (18 studies), and behavioral (2 studies). Significant changes in at least 1 potential neurobiological mechanism were reported in 5 studies, and significant effects for at least 1 cognitive outcome were also found in 5 studies. One of 2 studies reported a significant effect for self-regulation, but neither study reported a significant impact on mental health. Limitations: Small number of studies and high levels of study heterogeneity. Conclusions: The strongest evidence was found for improvements in physical self-perceptions, which accompanied enhanced self-esteem in the majority of studies measuring these outcomes. Few studies examined neurobiological and behavioral mechanisms, and we were unable to draw conclusions regarding their role in enhancing cognitive and mental health

Tennis grunts communicate acoustic cues to sex and contest outcome

Despite their ubiquity in human behaviour, the communicative functions of nonverbal vocalisations remain poorly understood. Here, we analysed the acoustic structure of tennis grunts, nonverbal vocalisations produced in a competitive context. We predicted that tennis grunts convey information about vocalizer and context, similar to nonhuman vocal displays. Specifically, we tested whether the fundamental frequency (F0) of tennis grunts conveys static cues to a player’s sex, height, weight, and age, and covaries dynamically with tennis shot type (a proxy of body posture) and the progress and outcome of male and female professional tennis contests. We also performed playback experiments (using natural and resynthesised stimuli) to assess the perceptual relevance of tennis grunts. The F0 of tennis grunts predicted player sex, but not age or body size. Serve grunts had higher F0 than forehand and backhand grunts, grunts produced later in contests had higher F0 than those produced earlier, and grunts produced during contests that players won had a lower F0 than those produced during lost contests. This difference in F0 between losses and wins emerged early in matches, and did not change in magnitude as the match progressed, suggesting a possible role of physiological and/or psychological factors manifesting early or even before matches. Playbacks revealed that listeners use grunt F0 to infer sex and contest outcome. These findings indicate that tennis grunts communicate information about both vocalizer and contest, consistent with nonhuman mammal vocalisations