ArticlePublisher preview available

The Role of Sexual Selection in the Evolution of Facial Displays in Male Non-human Primates and Men

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Objective Sexual selection theory provides a framework through which some facial displays of male non-human primates can be investigated and understood. Here, we explore how both intra- and inter-sexual selection may influence facial morphology, physiology, and the behavior of male primates inhabiting diverse social and ecological environments.Methods First, we will review how elements of the ecological environment, such as the spatio-temporal distribution of food, interacting with the diet of different species, shapes the social and mating systems of primates. In turn, these dynamics then influence how facial expressions, colors, and shapes are utilized in both the competition for and attraction of mates. We will focus on sexually dimorphic facial features that exhibit variation in their expression among males and that can be linked to differences in proxies of reproductive success.ResultsFacial displays can generally be divided into four types, each commonly associated with certain mating systems, social systems, and sexually selective pressures. Facial expressions, skin color, pelage, and variation in facial shape, can be involved in either mediating intra-sexual competition, mate choice, or a combination of both.Conclusions Certain aspects of male non-human primate facial displays are likely to be shaped by processes of both intra- and inter-sexual selection. Accordingly, homologies and analogies between human and non-human primate facial displays can inform us of the processes of sexual selection that may have been operating throughout human evolution.
This content is subject to copyright. Terms and conditions apply.
ORIGINAL ARTICLE
The Role of Sexual Selection in the Evolution of Facial
Displays in Male Non-human Primates and Men
Rachel M. Petersen
1,2
&James P. Higham
1,2
Received: 22 January 2020 /Revised: 1 May 2020 / Accepted: 18 May 2020
#Springer Nature Switzerland AG 2020
Abstract
Objective Sexual selection theory provides a framework through which some facial dis-
plays of male non-human primates can be investigated and understood. Here, we explore
how both intra- and inter-sexual selection may influence facial morphology, physiology, and
the behavior of male primates inhabiting diverse social and ecological environments.
Methods First, we will review how elements of the ecological environment, such as the
spatio-temporal distribution of food, interacting with the diet of different species,
shapes the social and mating systems of primates. In turn, these dynamics then
influence how facial expressions, colors, and shapes are utilized in both the competition
for and attraction of mates. We will focus on sexually dimorphic facial features that
exhibit variation in their expression among males and that can be linked to differences
in proxies of reproductive success.
Results Facial displays can generally be divided into four types, each commonly
associated with certain mating systems, social systems, and sexually selective pressures.
Facial expressions, skin color, pelage, and variation in facial shape, can be involved in
either mediating intra-sexual competition, mate choice, or a combination of both.
Conclusions Certain aspects of male non-human primate facial displays are likely to be
shaped by processes of both intra- and inter-sexual selection. Accordingly, homologies
and analogies between human and non-human primate facial displays can inform us of the
processes of sexual selection that may have been operating throughout human evolution.
Keywords Sexual selection .Male-male competition .Female mate choice .Facial
expressions .Badges of status .Facial masculinity .Facial symmetry
Adaptive Human Behavior and Physiology
https://doi.org/10.1007/s40750-020-00139-z
*Rachel M. Petersen
rachel.petersen@nyu.edu
1
Department of Anthropology, New York University, 25 Waverly Place, New York,
NY 10003, USA
2
New York Consortium in Evolutionary Primatology, New York, NY, USA
Published online: 31 March 2020
(2020) 6:249276
/
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Third, in some species, males show dynamic changes in appearance. Such changes in appearance o en covary with competitive ability or health (reviewed in Petersen & Higham, 2020), and can covary with female preferences (e.g., Setchell, 2005). Thus, in line with the first assumption of evolutionary theories of attractiveness, specific male characteristics can be predictive of male quality, and might be preferred by females. ...
... While we know that secondary sexual characteristics a ect cognitive processes such as attention in humans (Garza & Byrd-Craven, 2023;Yang et al., 2015), this topic has been virtually unexplored in great apes. However, to develop a full understanding of the evolutionary underpinnings of such attentional biases, it is important to test a wide range of species (Smith et al., 2018), ideally with di erent mating systems (Petersen & Higham, 2020). Because orang-utans are a suitable model organism for this topic, part of this thesis investigates whether Bornean orangutans show cognitive biases towards flanged males. ...
... For example, primates attend to faces of conspecifics (Kano et al., 2012) and discriminate faces based on di erent characteristics, such as emotional expressions (Pritsch et al., 2017) and familiarity (Leinwand et al., 2022;Lewis, 2017;van Berlo et al., 2023). Importantly, primate faces can also signal cues that are relevant for mate choice, such as health or dominance (Petersen & Higham, 2020). Consequently, primates might have cognitive biases related to sexually relevant facial characteristics. ...
... Research linking the fWHR and facial lower-height/full-height to socially relevant Dominance-related personality traits (e.g., Dominance, Assertiveness, Neuroticism) suggests the potential role of static facial features as a cue in intraspecific communication (Table 1), which is long-lasting and available to many bystanders (compared to signalling through short-term facial expressions aimed at one or a few bystanders; Petersen & Higham, 2020). Sexual selection, including inter-and intra-sexual selection, has been hypothesised to generate and maintain facial-personality links Petersen & Higham, 2020;Wilson, Weiss et al., 2020). ...
... Research linking the fWHR and facial lower-height/full-height to socially relevant Dominance-related personality traits (e.g., Dominance, Assertiveness, Neuroticism) suggests the potential role of static facial features as a cue in intraspecific communication (Table 1), which is long-lasting and available to many bystanders (compared to signalling through short-term facial expressions aimed at one or a few bystanders; Petersen & Higham, 2020). Sexual selection, including inter-and intra-sexual selection, has been hypothesised to generate and maintain facial-personality links Petersen & Higham, 2020;Wilson, Weiss et al., 2020). Intra-sexual selection acts on morphological or behavioural traits that increase an individual´s competitive ability. ...
... Intra-sexual selection acts on morphological or behavioural traits that increase an individual´s competitive ability. In primates (Table 1) including humans (e.g., Geniole et al., 2015;Haselhuhn et al., 2015), fWHR and potentially other facial features might act as badges of status (Bergman & Sheehan, 2013;Petersen & Higham, 2020), reflecting status-seeking motivations, Dominancerelated personality traits and fighting ability with the potential role of modulating social interactions. Indeed, evidence that faces of men are wider during early sexual maturity, compared with faces of older men, suggests that fWHR plays a role in intra-sexual competition (Summersby et al., 2022). ...
Article
Full-text available
When looking at others, primates primarily focus on the face – detecting the face first and looking at it longer than other parts of the body. This is because primate faces, even without expression, convey trait information crucial for navigating social relationships. Recent studies on primates, including humans, have linked facial features, specifically facial width-to-height ratio (fWHR), to rank and Dominance-related personality traits, suggesting these links’ potential role in social decisions. However, studies on the association between dominance and fWHR report contradictory results in humans and variable patterns in nonhuman primates. It is also not clear whether and how nonhuman primates perceive different facial cues to personality traits and whether these may have evolved as social signals. This review summarises the variable facial-personality links, their underlying proximate and evolutionary mechanisms and their perception across primates. We emphasise the importance of employing comparative research, including various primate species and human populations, to disentangle phylogeny from socio-ecological drivers and to understand the selection pressures driving the facial-personality links in humans. Finally, we encourage researchers to move away from single facial measures and towards holistic measures and to complement perception studies using neuroscientific methods.
... As reported in chimpanzees, certain facial movements such as BT display (AU10 + 12 + 25) [27] have been associated with distinctive contexts such as fear followed by aggression in Sumatran orangutans (P. abelii) [84]. ...
Article
Full-text available
The Facial Action Coding System (FACS) is an anatomically based system to study facial expression in humans. Currently, it is recognized that nonhuman animals, particularly nonhuman primates, have an extensive facial ethogram that changes according to the context and affective state. The facial expression of great apes, the closest species to humans, has been studied using the ChimpFACS and OrangFACS as reliable tools to code facial expressions. However, although the FACS does not infer animal emotions, making additional evaluations and associating the facial changes with other parameters could contribute to understanding the facial expressions of nonhuman primates during positive or negative emotions. The present review aims to discuss the neural correlates and anatomical components of emotional facial expression in great apes. It will focus on the use of Facial Action Coding Systems (FACSs) and the movements of the facial muscles (AUs) of chimpanzees, orangutans, and gorillas and their possible association with the affective state of great apes.
... Within the last decade technology has allowed for more objective and repeatable methods that could be applied across multiple taxa (Lehnert et al, 2011;Stevens et al, 2007;. Recent research has found that specific information content is displayed by certain taxa, such as immune health, reproductive health, and badges of status (Snyder, 2021;Petersen et al, 2020;Young et al, 2020). In terms of disease prevention, it has been suggested that the intense red colouration of the bald-faced ukarai may indicate overall health to conspecifics; when infected with blood parasites, the face of the ukarai turns pale providing an honest indicator of parasitic infection to conspecifics (Mayor et al, 2015). ...
Preprint
Full-text available
Sexual selection is driven by two main mechanisms, intrasexual selection and intersexual selection. Classically, elaborate male ornamentation is considered to function as an intersexual signal, in which females choose potential mates on the basis of their conspicuous colouration. However, some studies have shown that male sexual ornamentation may also serve as an intersexual signal of strength or dominance (as ‘badges of status’), mediating conflict between males. Among primates, such signals often comprise bright colouration on the face, scrotum, or chest. The potential function as a badge of status of the dark facial colouration seen in a number of primate species is less explored. In this study of male Barbary macaques (Macaca sylvanus) living in a semi-free ranging enclosure at Trentham Monkey Forest, I predicted that darker faced males would be higher ranked, receive higher rates of submissive behavior, and spend less time with males in close proximity, respectively. I found that male facial colour was not related to rank, rate of submissions received or patterns of proximity to conspecifics. Thus, this work does not support the hypothesis that dark facial colouration serves as an intrasexual badge of status in this species.
... Sensory systems play critical roles in all aspects of daily life, including mate selection, avoiding predators, and finding food. [1][2][3][4] During foraging, primates engage and integrate their senses throughout multiple stages of food detection and assessment. [5][6][7] However, much remains unknown about food sensory cues and signals, and about primate sensory morphology, genetics and behaviors. ...
Article
Twenty years ago, Dominy and colleagues published "The sensory ecology of primate food perception," an impactful review that brought new perspectives to understanding primate foraging adaptations. Their review synthesized information on primate senses and explored how senses informed feeding behavior. Research on primate sensory ecology has seen explosive growth in the last two decades. Here, we revisit this important topic, focusing on the numerous new discoveries and lines of innovative research. We begin by reviewing each of the five traditionally recognized senses involved in foraging: audition, olfaction, vision, touch, and taste. For each sense, we provide an overview of sensory function and comparative ecology, comment on the state of knowledge at the time of the original review, and highlight advancements and lingering gaps in knowledge. Next, we provide an outline for creative, multidisciplinary, and innovative future research programs that we anticipate will generate exciting new discoveries in the next two decades.
Article
Objectives Facial width‐to‐height ratio (fWHR) has been widely investigated in the context of its role in visual communication, though there is a lack of consensus about how fWHR serves as a social signal. To better understand fWHR variation in a comparative context, we investigate the associations between fWHR and canine crown height (CCH) and body mass, respectively, among two chimpanzee subspecies ( Pan troglodytes schweinfurthii , Pan troglodytes troglodytes ) and bonobos ( Pan paniscus ). Materials and Methods We collected landmark data from 3D surface models of 86 Pan cranial specimens to quantify fWHR and upper CCH, and to estimate body mass. We used Spearman's r and Kruskal‐Wallis tests to test for significant relationships among variables, and to assess sexual dimorphism. Results There is an inverse relationship between fWHR and CCH in both sexes of Pan , however there are interpopulation differences in the relationship between fWHR and CCH among Pan taxa. Pan paniscus have relatively wide faces and small canine crowns, and wide faces in Pan t. schweinfurthii males may be driven by body size constraints. Pan troglodytes and Pan paniscus show fWHR dimorphism, and Pan paniscus have significantly higher fWHRs than do either Pan troglodytes subspecies. Discussion Our findings indicate that CCH and facial breadth may serve subtly different signaling functions among Pan taxa. Further research into the circumstances in which wide faces evolved among chimpanzees and bonobos will likely afford deeper insights into the function of relatively wide faces in the context of visual signaling among humans and our extinct hominin relatives.
Article
Full-text available
Primate faces provide information about a range of variant and invariant traits, including some that are relevant for mate choice. For example, faces of males may convey information about their health or genetic quality through symmetry or facial masculinity. Because perceiving and processing such information may have bearing on the reproductive success of an individual, cognitive systems are expected to be sensitive to facial cues of mate quality. However, few studies have investigated this topic in non-human primate species. Orang-utans are an interesting species to test mate-relevant cognitive biases, because they are characterised by male bimaturism: some adult males are fully developed and bear conspicuous flanges on the side of their face, while other males look relatively similar to females. Here, we describe two non-invasive computerised experiments with Bornean orang-utans (Pongo pygmaeus), testing (i) immediate attention towards large flanges and symmetrical faces using a dot-probe task (N = 3 individuals; 2F) and (ii) choice bias for pictures of flanged males over unflanged males using a preference test (N = 6 individuals; 4F). In contrast with our expectations, we found no immediate attentional bias towards either large flanges or symmetrical faces. In addition, individuals did not show a choice bias for stimuli of flanged males. We did find exploratory evidence for a colour bias and energy efficiency trade-offs in the preference task. We discuss our null results and exploratory results in the context of the evolutionary history of Bornean orang-utans, and provide suggestions for a more biocentric approach to the study of orang-utan cognition.
Article
Full-text available
Primates are remarkably colourful in comparison to other mammals. In particular, several species exhibit red–orange pelage or bright red skin, with the latter thought to signal status in intraspecific dominance interactions or to signal fertility. One potential driver of the interspecific diversity in red coloration is the primate visual system, which, uniquely among eutherian mammals, varies interspecifically and even between conspecifics in the ability to distinguish red and green (trichromatic colour vision). Previous comparative studies, however, have produced conflicting results regarding the proposed link between coloration and visual system. We employed an updated, sex-specific dataset of primate coloration and visual systems to re-examine the relationship between colour vision and red coloration across the entire order. With a few exceptions, increased colour visual ability is not significantly associated with the presence of red skin on the face or anogenital region, nor of red–orange pelage. We discuss possible reasons for the lack of colour–vision associations and suggest that dichromatic colour vision still facilitates effective signalling between conspecifics.
Article
Presidents cite many reasons to justify their decisions to use military force. Regardless of the explanation provided, putting soldiers in harm's way entails a high degree of risk. Some presidents are more willing than others to undertake risky policies, and psychological dispositions help to account for their willingness. According to evolutionary psychology theories of conflict, facial characteristics serve as important cues of aggression, and a substantial body of empirical evidence supports the association between the facial width-to-height ratio (FWHR) and conflict behavior. All else equal, individuals with greater FWHRs are more likely to choose aggressive foreign policies. Empirical analyses of 1953–2000 show that US presidents with higher FWHRs are four times more likely than those with lower FWHRs to use military force. The results hold independent of traditional explanations such as power, ongoing war, elections, the misery index, and alternative measures of leader psychology.
Article
Parasites, ranging from microscopic viruses and bacteria to macroscopic worms and arthropods, are a fundamental part of life for all animals. Parasites affect almost all aspects of their host’s behavior, and conversely, host behavior affects parasites in countless ways. This book examines the many ways in which animal behavior and parasitism are interlinked, emphasizing the critical role of bi-directional feedbacks between the two phenomena. Chapters explore five central themes (social behavior, movement behavior, sexual selection and mating behavior, parasite modification of host behavior, and behavior defenses against parasites) by synthesizing current knowledge and proposing new research directions for the future. The book delivers essential background and cutting-edge ideas in the study of animal behavior and parasitism that will resonate with students new to the field and more seasoned researchers alike.
Article
Full-text available
Objectives Intra-sexual selection has shaped the evolution of sexually dimorphic traits in males of many primates, including humans. In men, sexual dimorphism in craniofacial shape (i.e. facial masculinity) and facial hair have both been shown to communicate aspects of social and physical dominance intra-sexually. However, less attention has been given to how variation in physical and social dominance among receivers impacts on perceptions of facial masculinity and beards as intra-sexual signals of formidability.Methods In the current study, male participants (N = 951) rated male faces varying in masculinity and beardedness when judging masculinity, dominance and aggressiveness. These participants also responded to scales measuring their psychological dominance, sexual jealousy, status seeking, and masculine morphology (facial masculinity, facial hair, and height).ResultsBeardedness exerted strong effects over clean-shaven faces on ratings of masculinity, dominance, and aggressiveness. Trait ratings of masculinity, dominance, and aggressiveness rose linearly with increasing craniofacial masculinity. The significant facial masculinity × facial hair interaction suggests that beardedness caused strong effects on all trait ratings over clean-shaven faces at every level of facial masculinity. Participants with full beards also reported higher scores on dominance and assertiveness scales. Participants high in dominance and assertiveness also gave higher ratings for dominance, but not masculinity or aggressiveness, to bearded over clean-shaven faces. Participants low in intra-sexual jealousy rated clean-shaven and/or feminised faces as less dominant, less masculine, and less aggressive.Conclusions These findings demonstrate that facial hair enhances perceptions of masculinity, dominance, and aggressiveness above ratings of facial masculinity, potentially by augmenting masculine craniofacial features. Individual differences in intra-sexual dominance showed associations with judgments of facial hair but not facial masculinity. Our study demonstrates that when two sexually dimorphic androgen dependent facial traits are judged in concert, ornamental rather than structural masculine facial features underpin men’s intra-sexual judgments of formidability.
Article
Full-text available
Humans and great apes are highly social species, and encounter conspecifics throughout their daily lives. During social interactions, they exchange information about their emotional states via expressions through different modalities including the face, body and voice. In this regard, their capacity to express emotions, intentionally or unintentionally, is crucial for them to successfully navigate their social worlds and to bond with group members. Darwin (1872) stressed similarities in how humans and other animals express their emotions, particularly with the great apes. Here, we show that emotional expressions have many conserved, yet also a number of divergent features. Some theorists consider emotional expressions as direct expressions of internal states, implying that they are involuntary, cannot be controlled and are inherently honest. Others see them as more intentional and/ or as indicators of the actor's future behavior. After reviewing the human and ape literature, we establish an integrative, evolutionary perspective and provide evidence showing that these different viewpoints are not mutually exclusive. Recent insights indicate that, in both apes and humans, some emotional expressions can be controlled or regulated voluntarily, including in the presence of audiences, suggesting modulation by cognitive processes. However, even non-intentional expressions such as pupil dilation can nevertheless inform others and influence future behavior. In sum, while showing deep evolutionary homologies across closely related species, emotional expressions show relevant species variation.
Article
Full-text available
The strength and direction of sexual selection via female choice on masculine facial traits in men is a paradox in human mate choice research. While masculinity may communicate benefits to women and offspring directly (i.e. resources) or indirectly (i.e. health), masculine men may be costly as long-term partners owing to lower paternal investment. Mating strategy theory suggests women's preferences for masculine traits are strongest when the costs associated with masculinity are reduced. This study takes a multivariate approach to testing whether women's mate preferences are context-dependent. Women (n = 919) rated attractiveness when considering long-term and short-term relationships for male faces varying in beardedness (clean-shaven and full beards) and facial masculinity (30% and 60% feminized, unmanipulated, 30% and 60% masculinized). Participants then completed scales measuring pathogen, sexual and moral disgust, disgust towards ectoparasites, reproductive ambition, self-perceived mate value and the facial hair in partners and fathers. In contrast to past research, we found no associations between pathogen disgust, self-perceived mate value or reproductive ambition and facial masculinity preferences. However, we found a significant positive association between moral disgust and preferences for masculine faces and bearded faces. Preferences for beards were lower among women with higher ectoparasite disgust, providing evidence for ectoparasite avoidance hypothesis. However, women reporting higher pathogen disgust gave higher attractiveness ratings for bearded faces than women reporting lower pathogen disgust, providing support for parasite-stress theories of sexual selection and mate choice. Preferences for beards were also highest among single and married women with the strongest reproductive ambition. Overall, our results reflect mixed associations between individual differences in mating strategies and women's mate preferences for masculine facial traits.
Article
Full-text available
Discriminating conspecifics from heterospecifics can help avoid costly interactions between closely related sympatric species. The guenons, a recent primate radiation, exhibit high degrees of sympatry and form multi-species groups. Guenons have species-specific colorful face patterns hypothesized to function in species discrimination. Here, we use a machine learning approach to identify face regions most essential for species classification across fifteen guenon species. We validate these computational results using experiments with live guenons, showing that facial traits critical for accurate classification influence selective attention toward con- and heterospecific faces. Our results suggest variability among guenon species in reliance on single-trait-based versus holistic facial characteristics for species discrimination, with behavioral responses and computational results indicating variation from single-trait to whole-face patterns. Our study supports a role for guenon face patterns in species discrimination, and shows how complex signals can be informative about differences between species across a speciose and highly sympatric radiation.
Article
Full-text available
Facial width-to-height ratio (fWHR) is associated with social dominance in human and non-human primates, which may reflect the effects of testosterone on facial morphology and behaviour. Given that testosterone facilitates status-seeking motivation, the association between fWHR and behaviour should be contingent on the relative costs and benefits of particular dominance strategies across species and socioecological contexts. We tested this hypothesis in bonobos (Pan paniscus), who exhibit female dominance and rely on both affiliation and aggression to achieve status. We measured fWHR from facial photographs, affiliative dominance with Assertiveness personality scores and agonistic dominance with behavioural data. Consistent with our hypothesis, agonistic and affiliative dominance predicted fWHR in both sexes independent of age and body weight, supporting the role of status-seeking motivation in producing the link between fWHR and socioecologically relevant dominance behaviour across primates.
Chapter
The neotropical primate family Pitheciidae consists of four genera Cacajao (uacaris), Callicebus (titis), Chiropotes (bearded sakis) and Pithecia (sakis), whose 40+ species display a range of sizes, social organisations, ecologies and habitats. Few are well known and the future survival of many is threatened, yet pitheciines have been little studied. This book is the first to review the biology of this fascinating and diverse group in full. It includes fossil history, reviews of the biology of each genus and, among others, specific treatments of vocalisations and foraging ecology. These studies are integrated into considerations of current status and future conservation requirements on a country-by-country basis for each species. A state-of-the-art summary of current knowledge, Evolutionary Biology and Conservation of Titis, Sakis and Uacaris is a collective effort from all the major researchers currently working on these remarkable animals.
Chapter
INTRODUCTION Studies of sexual selection in primates or other animals tend to focus on outcomes – sexual dimorphism, differential mating and reproductive success for adult males and females. However, adult sex differences represent the end-points of complex and interrelated developmental processes, and arise from differences in behaviour and physiology between males and females. In most vertebrates, including primates, the sexes are nearly identical in size and shape during early development, and adult differences are thus the product of divergent growth strategies (Badyaev, 2002). Sex differences in growth and development arise as a result of the different roles played by the two sexes in reproduction and the corresponding determinants of reproductive success for males and females, which are intricately linked to social organisation and mating system (Kappeler & van Schaik, 2002). Evolution shapes processes throughout the lifecycle, and the mechanisms for partitioning resources among growth, reproduction and survival are, to a large part, established during development, while consequences may not be observed until the end of the lifespan. A developmental perspective is therefore fundamental to studies of the action of sexual selection (see also Pereira & Leigh, 2003). For mammals in general, and primates in particular, past work on sexual selection and development has concentrated on the influence of growth on sexual dimorphism (e.g. ungulates: Jarman, 1983; Georgiadis, 1985; Clutton-Brock et al., 1992; seals: Trillmich, 1996; primates: Leigh, 1995; Pereira & Leigh, 2003) or growth and life-history traits such as rates of reproduction (e.g. Gordon, 1989; Pontier et al. , 1989; Lee & 2003).
Book
The book discusses the diversity of mechanisms by which prey can avoid or survive attacks by predators, both from ecological and evolutionary perspectives. There is a particular focus on sensory mechanisms by which prey can avoid being detected, avoid being identified, signal (perhaps sometimes dishonestly) to predators that they are defended or unpalatable. The book is divided into three sections. The first considers detection avoidance through, for example, background matching, disruptive patterning, countershading and counterillumination, or transparency and reflective silvering. The second section considers avoiding or surviving an attack if detection and identification by the predator has already taken place (i.e., secondary defences). The key mechanism of this section is aposematism: signals that warn the predator that a particular prey type is defended. One particularly interesting aspect of this is the sharing of the same signal by more than one defended species (the phenomenon of Mullerian mimicry). The final section considers deception of predators. This may involve an undefended prey mimicking a defended species (Batesian mimicry), or signals that deflect predator’s attention or signals that startle predators. The book provides the first comprehensive survey of adaptive coloration in a predator-prey context in thirty years.