Of bonds and boundaries: what is the modern role of anthropomorphism in primatological studies?

Anthropomorphism (and its obverse, zoomorphism) continues to shift and propel us toward changing perspectives on ourselves and other animals. Discussions of anthropomorphism in primate behavior are ostensibly about our use and definition of terms, but ultimately reflect our views of what is unique to humans or unknowable in other animals. Primatologists doing long-term fieldwork report on the bonds that are inevitably formed through familiarity with their study subjects and how anecdotes and anthropomorphism help them to gain a contextualized view of animal lives. This fuller view of animal society serves as an aid to understanding different rationalities and provides a more effective modern role for anthropomorphism than does seeking to demonstrate isomorphic capacities in alloprimates. Although most ordinary language terms are accepted among primatologists, "primate culture" serves as an example of a term and a concept that overreached acceptable anthropomorphic limits when defined to accord with definitions of modern human culture. Comparing similar behavioral forms as the product of similar selective pressures acting on specific early traits, producing homoplasies through convergent evolution, provides a nonanthropomorphic basis for seeking similarities in human and alloprimate behavior.     

“Animals Like Us”: Identifying with Nonhuman Animals and Support for Nonhuman Animal Rights

While anthropomorphizing nonhuman animals has been shown to increase identification with them and, by extension, concern for their wellbeing, little research has directly tested whether identifying with nonhuman animals is similarly associated with concern for their wellbeing. We tested hypotheses related to this premise across three cross-sectional studies. In study 1 (n = 224), we tested the hypothesis that therians—a group of people who self-identify with nonhuman animals, show greater concern for nonhuman animal rights than non-therian furries—people with a fan-like interest in media featuring anthropomorphized animal characters. In study 2 (n = 206), we further tested this hypothesis using implicit and explicit measures of identification with nonhuman animals to predict behavioral intentions to support nonhuman animal rights. In study 3 (n = 182), we tested the generalizability of our findings in a sample of undergraduate students. Taken together, the studies show that explicit, but not implicit, identification with nonhuman animals predicts greater support for their rights. The implications of these findings for research on anthropomorphism and animal rights activism are discussed, as well as the limitations of these findings and possible avenues for future research.     

Anthropomorphism,anthropectomy, and the null hypothesis

We examine the claim that the methodology of psychology leads to a bias in animal cognition research against attributing “anthropomorphic” properties to animals (Sober in Thinking with animals: new perspectives on anthropomorphism. Columbia University Press, New York, pp 85–99, 2005; de Waal in Philos Top 27:225–280, 1999). This charge is examined in light of a debate on the role of folk psychology between primatologists who emphasize similarities between humans and other apes, and those who emphasize differences. We argue that while in practice there is sometimes bias, either in the formulation of the null hypothesis or in the preference of Type-II errors over Type-I errors, the bias is not the result of proper use of the Neyman and Pearson hypothesis testing method. Psychologists’ preference for false negatives over false positives cannot justify a preference for avoiding anthropomorphic errors over anthropectic (Gk. anthropos—human; ektomia—to cut out) errors.     

Thinking about Cats or Dogs Provides Relief from Social Rejection

Past research shows that anthropomorphizing animals and nonhuman objects is correlated with unmet social needs (e.g., loneliness), and momentary feelings of social rejection can be soothed by thinking about a pet or by having a dog nearby. The current work tested whether thinking of names for cats and dogs improves wellbeing after social rejection, as well as whether this phenomenon occurs because of a unique quality of animals or because of anthropomorphism more generally. In three studies, participants relived a past experience of social rejection, social acceptance, or a physical injury (a control condition), after which they reported their current wellbeing. Next, participants named either cats or dogs (studies 1, 2, 3), people (study 2), or plastic toys (study 3) before reporting their current wellbeing for a second time. Across all three studies, naming cats or dogs reduced feelings of social rejection. Naming anthropomorphic plastic toys, however, produced a similar effect. To test the role of anthropomorphism in this phenomenon, study 3 also measured participants’ chronic tendency to anthropomorphize and included a condition in which participants only viewed animals or toys. Rejected participants who simply viewed photos of cats or dogs (without naming them) experienced improved wellbeing if they were already dispositionally inclined to engage in anthropomorphism. Collectively, these results suggest that briefly thinking about cats or dogs is an effective strategy for improving feelings of social rejection and that general processes involving anthropomorphism can produce this ameliorative effect.     

Molecules,fossils, and the origin of tetrapods

Summary Since the discovery of the coelacanth, Latimeria chalumnae, more than 50 years ago, paleontologists and comparative morphologists have debated whether coelacanths or lungfishes, two groups of lobe-finned fishes, are the closest living relatives of land vertebrates (Tetrapoda). Previously, Meyer and Wilson (1990) determined partial DNA sequences from two conservative mitochondrial genes and found support for a close relationship of lungfishes to tetrapods. We present additional DNA sequences from the 12S rRNA mitochondria gene for three species of the two lineages of lungfishes that were not represented in the first study: Protopterus annectens and Protopterus aethiopicus from Africa and Neoceratodus forsteri (kindly provided by B. Hedges and L. Maxson) from Australia. This extended data set tends to group the two lepidosirenid lungfish lineages (Lepidosiren and Protopterus) with Neoceratodus as their sister group. All lungfishes seem to be more closely related to tetrapods than the coelacanth is. This result appears to rule out the possibility that the coelacanth lineage gave rise to land vertebrates. The common ancestor of lungfishes and tetrapods might have possessed multiple morphological traits that are shared by lungfishes and tetrapods [Meyer and Wilson (1990) listed 14 such traits]. Those traits that seem to link Latimeria and tetrapods are arguably due to convergent evolution or reversals and not to common descent. In this way, the molecular tree facilitates an evolutionary interpretation of the morphological differences among the living forms. We recommended that the extinct groups of lobe-finned fishes be placed onto the molecular tree that has lungfishes and not the coelacanth more closely related to tetrapods. The placement of fossils would help to further interpret the sequence of morphological events and innovations associated with the origin of tetrapods but appears to be problematic because the quality of fossils is not always high enough, and differences among paleontologists in the interpretation of the fossils have stood in the way of a consensus opinion for the branching order among lobefinned fishes. Marshall and Schultze (1992) criticized the morphological analysis presented by Meyer and Wilson (1990) and suggest that 13 of the 14 morphological traits that support the sister group relationship of lungfishes and tetrapods are not shared derived characters. Here we present further alternative viewpoints to the ones of Marshall and Schultze (1992) from the paleontological literature. We argue that all available information (paleontological, neontological, and molecular data) and rigorous cladistic methodology should be used when relating fossils and extant taxa in a phylogenetic framework. Offprint requests to: Axel Meyer     

Sociality Motivation and Anthropomorphic Thinking about Pets

Sociality motivation, the need to feel socially connected with others, has been proposed as an important determinant of individual variation in anthropomorphic thinking. Specifically, it has been suggested that people who are socially isolated or disconnected will tend to infer more human-like mental states in animals and other nonhuman agents (computers, robots, metaphysical beings, etc.), than those who have higher levels of contact with other people. We investigated this hypothesis in a community-based sample of cat and dog owners, measuring degree of anthropomorphism by asking them which emotions they believed their pet was capable of experiencing, how likely they were to rely on it for social support, and how attached they were to it. Structural measures of social disconnection, including the number of other adults living in the household and the number of social contacts outside the home, were not generally associated with the tendency to think anthropomorphically about pets. However, owners living in households with no children (under the age of 16 years) reported higher levels of attachment to their pet than did those with children (B = 1.678, p < 0.001), and felt that they derived relatively more social support from it than they did from humans (F_(1,244) = 4.997, p < 0.05, partial η² = 0.020). In addition, a trait-based indicator of social disconnection (self-reported anxiety about human social relationships) was associated with a heightened tendency for owners to report turning to their pet for support (F_(1,244) = 19.617, p < 0.001, partial η² = 0.074), and attributing more human-like emotions to it (F_(1,244) = 8.354, p < 0.005, partial η² = 0.033). These findings support a link between social disconnection and anthropomorphic thinking in a community setting; they also suggest that different forms of social disconnection (structural and trait-based) may generate different types of sociality motivation, and thereby influence different facets of anthropomorphic thinking.     

Links between the discovery of primates and anatomical comparisons with humans,the chain of being,our place in nature,and racism

I focus on the crucial links between the discovery of nonhuman primates by Westerners, discussions on our place in nature, the chain of being, racism, and the history of primate comparative anatomy and of so‐called “anatomical human racial studies.” Strikingly, for more than a millennium humans knew more about the internal anatomy of a single monkey species than about that of their own bodies. This is because Galen used monkeys to infer human anatomy, in line with the human‐animal continuity implied by the Greek notion of scala naturae. With the rise of Christianity, nonhuman primates were increasingly seen in a negative way. A more positive view emerged in the 14th century when nonhuman primates were directly studied/seen by Europeans, culminating in Tyson's 1699 work showing that chimps share more gross anatomical similarities with humans than with monkeys. However, the discomfort caused by this human‐chimp similarity then led to a new idea of animal‐human discontinuity, now related not to anatomy but to “civilization”: between Europeans vs. non‐Europeans + other primates. Moreover, Linnaeus' Systema Naturae and the emergence of “anatomical racial studies” influenced by Camper's craniology then led to even more extreme ideas, such as the notion that Europeans were both mentally and morphologically “ideal.” Unfortunately the biased and often incorrect “results” of such studies, combined with ideas based on Darwin's “struggle for survival”, became crucial in propaganda that lead to the rise of eugenics in the end of the 19th/first half of 20th centuries and that culminated in Nazism. Since the 1950s there has been an emphasis on the continuity/unity between all human groups and other primates, in great part influenced by what happened during World War 2. Reviews such as this one are, therefore, particularly necessary to illuminate and guard against attitudes against “the Other” and racist ideologies that are re‐emerging in modern political discourse across the globe.     

Correlated evolution and independent contrasts.

The use of the independent contrast method in comparative tests is studied. It is assumed that: (i) the traits under investigation are subject to natural selection; (ii) closely related species are similar because they share many characteristics of their niche, inherited from a common ancestor; and (iii) the current adaptive significance of the traits is the focus of investigation. The main objection to the use of species values in this case is that third variables which are shared by closely related species confound the relationship between the focal traits. In this paper, I argue that third variables are largely not controlled by the contrast methods, which are designed to estimate correlated evolution. To the extent that third variables also show correlated evolution, the true relationship among the traits of interest will remain obscured. Although the independent contrast method does not resolve the influence of third traits it does, in principle, provide a greater resolution than the use of the species mean values. However, its validity depends on the applicability of an evolutionary model which has a substantial stochastic component. To illustrate the consequences of relaxing this assumption I consider an alternative model of an adaptive radiation, where species come to fill a fixed niche space. Under this model, the expected value for the contrast correlation differs from that for the species correlation. The two correlations differ because contrasts reflect the historical pattern of diversification among species, whereas the species values describe the present-day relationships among the species. If the latter is of interest, I suggest that assessing significance based on the species correlations can be justified, providing that attention is paid to the role of potentially confounding third traits. Often, differences between contrast and species correlations may be biologically informative, reflecting changes in correlations between traits as an adaptive radiation proceeds; contrasts may be particularly useful as a means of investigating past history, rather than current utility of traits.     

Calls,colours, shape,and genes: a multi‐trait approach to the study of geographic variation in the Amazonian frog Allobates femoralis

Evolutionary divergence in behavioural traits related to mating may represent the initial stage of speciation. Direct selective forces are usually invoked to explain divergence in mate‐recognition traits, often neglecting a role for neutral processes or concomitant differentiation in ecological traits. We adopted a multi‐trait approach to obtain a deeper understanding of the mechanisms behind allopatric divergence in the Amazonian frog, Allobates femoralis. We tested the null hypothesis that geographic distance between populations correlates with genetic and phenotypic divergence, and compared divergence between mate‐recognition (acoustic) and ecological (coloration, body‐shape) traits. We quantified geographic variation in 39 phenotypic traits and a mitochondrial DNA marker among 125 individuals representing eight populations. Geographic variation in acoustic traits was pronounced and tracked the spatial genetic variation, which appeared to be neutral. Thus, the evolution of acoustic traits tracked the shared history of the populations, which is unexpected for pan‐Amazonian taxa or for mate‐recognition traits. Divergence in coloration appeared uncorrelated with genetic distance, and might be partly attributed to local selective pressures, and perhaps to Batesian mimicry. Divergence in body‐shape traits was low. The results obtained depict a complex evolutionary scenario and emphasize the importance of considering multiple traits when disentangling the forces behind allopatric divergence. ©2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 826–838.     

Social responding to mirrors in rhesus macaques (Macaca mulatta): Effects of changing mirror location

Two rhesus macaques (Macaca mulatta) with a lifetime of continuous exposure to mirrors showed a dramatic and reliable reinstatement of social behavior directed toward the mirror when it was simply moved to a new location. These data are discussed in the context of repeated failures to find self-recognition in monkeys and several recent claims that a cessation of social behavior directed toward mirrors can be used as evidence for the beginning of self-recognition in nonhuman primates.     

Modeling of technical training of discus throwers in the period of significant changes of their mass-inertia characteristics

The use of artificial neural networks for simulation of the control of an anthropomorphic mechanism when its mass-inertia characteristics are changing is considered in this paper. It is shown in theory that the change in mass-inertia characteristics of the model does not have a linear relationship with the output parameter but a spurt-like change in the pattern of the output function after a certain threshold. The data of the model experiment served as a basis for a full-scale test with discus throwers who had different height-weight parameters during a year of study. Specific traits in the technique of standing discus throwing are shown, and their dependence on the changes of anthropometric characteristics of sportsmen.     

DEVELOPMENTAL NOISE,PHENOTYPIC PLASTICITY,AND ALLOZYME HETEROZYGOSITY IN DAPHNIA

Previous theories and studies have postulated negative correlations between allozyme heterozygosity and developmental noise and between heterozygosity and phenotypic plasticity. We examined these relationships for morphological and life-history traits of Daphnia magna in four independent experiments using two different Moscow populations and one German population. Clones were raised under a range of food levels or individual densities. Heterozygosity was scored at five allozyme loci in two experiments and at three loci in two others. Relative differences in developmental noise among clones with different heterozygosity levels were estimated as the pooled residual variation from an analysis of variation that removed the effects of macroenvironment, clones, and their interaction. Plasticity was measured as the amount of macroenvironmental variation plus genotype-by-environment interaction variation. We found a positive correlation between developmental noise and heterozygosity, although this correlation varied among traits and experiments. This result contradicts most previous claims about these relationships. In contrast, we found that phenotypic plasticity and heterozygosity were negatively correlated for some traits. Developmental noise and phenotypic plasticity were correlated for only two traits in two different experiments. This trait-specific relationship is in concordance with previous studies. Our results could not be explained by effects of developmental time, a previously hypothesized mechanism. We propose several explanations for our results and the disparate results of others that do not require that heterozygosity be the actual cause of variation in developmental noise.     

Genetic enhancement, social justice, and welfare-oriented patterns of distribution

The debate over the host of moral issues that genetic enhancement technology (GET) raises has been significant. One argument that has been advanced to impugn its moral legitimacy is the 'unfair advantage argument' (UAA), which states: allowing access to GET to be determined by socio-economic status would lead to unjust outcomes, namely, create a genetic caste system, and with it the exacerbation and perpetuation of existing socio-economic inequalities. Fritz Allhoff has recently objected to the argument, the kernel of which is that it conflates the use of the technology with its distribution. GET, he argues, would generate unjust outcomes only if it is distributed according to principles of an unjust pattern of distribution; for if we can determine what constitutes a 'just' distributive scheme, then the technology can be allocated according to the principles of that scheme. In this paper I argue the following cluster of related claims: (1) both UAA and Allhoff's proposed distributive schemes ignore the importance of non-genetic factors in the development of an individual's characteristics and capacities; (2) if we accept the view that it is good to prevent unjust outcomes that arise because some have exclusive access to GET, then we have to accept wide-ranging distributive schemes; (3) by tracking genetic and non-genetic factors wide-ranging schemes do violate in some sense the widely shared value of neutrality in liberal democracies.     

Random copying,frequency-dependent copying and culture change

Previous evolutionary analyses of human culture have found that a simple model of random copying, analogous to neutral genetic drift, can generate the distinct power-law frequency distribution of cultural traits that is typical of various real-world cultural datasets, such as first names, patent citations and prehistoric pottery types. Here, we use agent-based simulations to explore the effects of frequency-dependent copying (e.g., conformity and anti-conformity) on this power-law distribution. We find that when traits are actively selected on the basis of their frequency, then the power-law distribution is severely disrupted. Conformity generates a “winner-takes-all” distribution in which popular traits dominate, while anti-conformity generates a “humped” distribution in which traits of intermediate frequency are favoured. However, a more passive frequency-dependent “trimming”, in which traits are selectively ignored on the basis of their frequency, generates reasonable approximations to the power-law distribution. This frequency-dependent trimming may therefore be difficult to distinguish from genuine random copying using population-level data alone. Implications for the study of both human and nonhuman culture are discussed.     

Between‐sex genetic covariance constrains the evolution of sexual dimorphism in Drosophila melanogaster

Males and females share much of their genome, and as a result, intralocus sexual conflict is generated when selection on a shared trait differs between the sexes. This conflict can be partially or entirely resolved via the evolution of sex‐specific genetic variation that allows each sex to approach, or possibly achieve, its optimum phenotype, thereby generating sexual dimorphism. However, shared genetic variation between the sexes can impose constraints on the independent expression of a shared trait in males and females, hindering the evolution of sexual dimorphism. Here, we examine genetic constraints on the evolution of sexual dimorphism in Drosophila melanogaster cuticular hydrocarbon (CHC) expression. We use the extended G matrix, which includes the between‐sex genetic covariances that constitute the B matrix, to compare genetic constraints on two sets of CHC traits that differ in the extent of their sexual dimorphism. We find significant genetic constraints on the evolution of further dimorphism in the least dimorphic traits, but no such constraints for the most dimorphic traits. We also show that the genetic constraints on the least dimorphic CHCs are asymmetrical between the sexes. Our results suggest that there is evidence both for resolved and ongoing sexual conflict in D. melanogaster CHC profiles.     

Phenotypic similarity in sympatric crow species: Evidence of social convergence?

Crows, rooks, and ravens (Corvus spp.) display marked morphological and voice similarities that have been hypothesized to stem from competitive interactions, as a case of nonaposematic mimicry. Here, I test predictions of the mimicry hypothesis at the macrovolutionary scale, examining whether species morphological and acoustic traits covary with those of coexisting congeners, and whether phenotypic similarity has facilitated the coexistence of related species after secondary contact. Body size and the temporal patterns of the commonest call display high levels of similarity among sympatric species, even after controlling for the effect of shared climate and habitat, and phylogenetic constraints in the production of variation. When sister species differed in these acoustic and morphological traits, their transition to secondary sympatry was delayed relative to those with more similar traits. No similarity was found in the sexual call of crows, suggesting that convergence occurs only when function does not favour maintenance of species‐specific traits. Crow similarities in morphological and acoustic features may therefore be associated with coevolving interactions with congeners, in line with a broad array of studies documenting convergence among species that interact aggressively or forage communally.     

Morgan’s Canon, meet Hume’s Dictum: avoiding anthropofabulation in cross-species comparisons

How should we determine the distribution of psychological traits—such as Theory of Mind, episodic memory, and metacognition—throughout the Animal kingdom? Researchers have long worried about the distorting effects of anthropomorphic bias on this comparative project. A purported corrective against this bias was offered as a cornerstone of comparative psychology by C. Lloyd Morgan in his famous “Canon”. Also dangerous, however, is a distinct bias that loads the deck against animal mentality: our tendency to tie the competence criteria for cognitive capacities to an exaggerated sense of typical human performance. I dub this error “anthropofabulation”, since it combines anthropocentrism with confabulation about our own prowess. Anthropofabulation has long distorted the debate about animal minds, but it is a bias that has been little discussed and against which the Canon provides no protection. Luckily, there is a venerable corrective against anthropofabulation: a principle offered long ago by David Hume, which I call “Hume’s Dictum”. In this paper, I argue that Hume’s Dictum deserves a privileged place next to Morgan’s Canon in the methodology of comparative psychology, illustrating my point through a discussion of the debate over Theory of Mind in nonhuman animals.     

Complexities of Using Wild versus Captive Activity Budget Comparisons for Assessing Captive Primate Welfare

Activity budget comparisons between groups or individuals in the wild and those in captivity are commonly used to determine the range of wild-type behaviors that nonhuman animals in captivity perform. These comparisons are conducted with the view that individuals displaying a greater range of wild-type behaviors have enhanced welfare. Such comparisons have a greater appeal when it comes to primates because increased levels of anthropomorphism toward primates lead to welfare concerns. However, the validity of such comparisons has not been assessed. From the reviewed literature, some of the main complexities identified when defining “good welfare” using activity budgets were the ideas of behavioral motivation and adaptation, obstacles when using the wild as a benchmark for good welfare, study methods causing possible variances in behavior, and social and environmental factors. It is proposed that such influencing factors would be controlled for adequately in future studies with the use of multiple indices to measure welfare and methods that infer positive emotional states. It is hoped we can then build evidence of an animal’s emotional state and allow welfare to be inferred to a higher degree.     

ADAPTIVE SIGNIFICANCE OF FLOWER COLOR AND INTER-TRAIT CORRELATIONS IN AN IPOMOPSIS HYBRID ZONE

Flower color is often viewed as a trait that signals rewards to pollinators, such that the relationship between flower color and plant fitness might result from its association with another trait. We used experimental manipulations of flower color and nectar reward to dissociate the natural character correlations present in a hybrid zone between Ipomopsis aggregata and Ipomopsis tenuituba. Isozyme markers were used to follow the male and female reproductive success of these engineered phenotypes. One field experiment compared fitnesses of I. aggregata plants that varied only in flower color. Plants with flowers painted red received more hummingbird visits and sired more seeds than did plants with flowers painted pink or white to match those of hybrids and I. tenuituba. Our second field experiment compared fitnesses of I. aggregata, I. tenuituba, and hybrid plants in an unmanipulated array and in a second array where all flowers were painted red. In the unmanipulated array, I. aggregata received more hummingbird visits, set more seeds per flower, and sired more seeds per flower. These fitness differences largely disappeared when the color differences were eliminated. The higher male fitness of I. aggregata was due to its very high success at siring seeds on conspecific recipients. On both I. tenuituba and hybrid recipients, hybrid plants sired the most seeds, despite showing lower pollen fertility than I. aggregata in mixed donor pollinations in the greenhouse. Ipomopsis tenuituba had a fitness of only 13% relative to I. aggregata when traits varied naturally, compared to a fitness of 36% for white relative to red flowers when other traits were held constant.     

Harmonia axyridis invasions: Deducing evolutionary causes and consequences

I consider evolutionary approaches to deducing factors that have made the ladybird beetle Harmonia axyridis such a successful invader, and the contribution that studies of this species in its native range can make. Work aiming to demonstrate which (pre)adaptations have made the species so successful often fails to compare these putative characters with those of other ladybirds. This has led to a tendency for “argument by design”‐type claims on characters widely shared by non‐invasive coccinellids. There is good evidence from genetic studies that evolutionary change occurred in invasive populations, contributing to their success. There is some evidence for subsequent evolutionary change after the establishment of invasive H. axyridis, primarily in the native organisms with which the ladybird interacts. I show here that there appears to have been little adaptation in H. axyridis, over about 20 generations, to the alkaloids of one North American native intraguild prey, the ladybird Coleomegilla maculata. Studies of H. axyridis in its native range are important, as they provide a snapshot of the ancestral ladybird, unobscured by subsequent evolutionary change related to its invasiveness. They provide baseline data about phenomena such as interactions with natural enemies and intraguild predation, and they also can provide pointers as to how H. axyridis might further adapt in the regions it has colonized. Harmonia axyridis represents an ideal opportunity for greater international co‐operation between scientists studying this species in its native range in Asia and scientists studying it in Europe, America and Africa, where it is an invasive exotic.