Steven J Schapiro

Steven J Schapiro
University of Texas MD Anderson Cancer Center | MD Anderson · Michael E. Keeling Center for Comparative Medicine and Research

PhD

About

301
Publications
50,544
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8,329
Citations

Publications

Publications (301)
Article
In the human brain, the inferior frontal gyrus (IFG) is comprised of three morphological regions, which include the pars opercularis, pars triangularis, and pars orbitalis. These brains regions are implicated in a number of cognitive and linguistic functions, and the pars opercularis and pars triangularis of the language dominant hemisphere are col...
Article
The superior temporal sulcus (STS) is a conserved fold that divides the middle and superior temporal gyri. In humans, there is considerable variation in the shape, folding pattern, lateralization, and depth of the STS that have been reported to be associated with social cognition and linguistic functions. We examined the role that genetic factors p...
Article
Full-text available
Eye gaze is an important source of information for animals, implicated in communication, cooperation, hunting and antipredator behaviour. Gaze perception and its cognitive underpinnings are much studied in primates, but the specific features that are used to estimate gaze can be difficult to isolate behaviourally. We photographed 13 laboratory-hous...
Article
Full-text available
Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) primate gaze is indeed concealed from their conspecifics, and (...
Article
Humans and chimpanzees both exhibit a diverse set of tool use skills which suggests selection for tool manufacture and use occurred in the common ancestors of the two species. Our group has previously reported phenotypic and genetic associations between tool use skill and gray matter covariation, as quantified by source-based morphometry (SBM), in...
Article
Chimpanzees have consistent individual differences in behaviour, also referred to as personality. Similar to human personality structure, five dimensions are commonly found in chimpanzee studies that show evidence for convergent and predictive validity (Dominance, Openness, Extraversion, Agreeableness, and Reactivity/Undependability). These dimensi...
Article
Full-text available
Many claim that social stimuli are rewarding to primates, but few, if any, studies have explicitly demonstrated their reward value. Here, we examined whether chimpanzees would produce overt responses for the opportunity to view conspecific social, compared to dynamic (video: Experiment 1) and static (picture: Experiment 2) control content. We also...
Article
Determining the impact that the KIAA0319 gene has on primate brain morphology can provide insight into the evolution of human cognition and language systems. Here, we tested whether polymorphisms in KIAA0319 in chimpanzees account for gray matter volumetric variation in brain regions implicated in language and communication (particularly within the...
Article
Aged memory-impaired cynomolgus monkeys had significantly lower levels of cerebrospinal amyloid (Aβ42 ) and serum testosterone compared with young animals and non-memory-impaired controls. Our findings confirm similar findings in the human and substantiate the usefulness of the cynomolgus monkey as a spontaneous model for aging-associated senile de...
Article
Food-associated calls have received much research attention due to their potential to refer to discovered food in a word-like manner. Studies have found that in many species, food-associated calls attract receivers to the food patch, suggesting these calls play roles in food sharing, cooperation and competition. Additionally, in various species, th...
Article
Previous studies of aging cynomolgus monkeys from our group identified spontaneous age-associated cognitive declines associated with biomarkers and brain lesions reminiscent of Alzheimer's Disease (AD), in a proportion of aged monkeys. However, the molecular mechanisms that underlie the spontaneous amyloid disorders and cognitive declines observed...
Article
Full-text available
Rawski et al. revisit our recent findings suggesting the latent ability to process nonadjacent dependencies ("Non-ADs") in monkeys and apes. Specifically, the authors question the relevance of our findings for the evolution of human syntax. We argue that (i) these conclusions hinge upon an assumption that language processing is necessarily hierarch...
Article
Early life experiences, including separation from caregivers, can result in substantial, persistent effects on neural, behavioral, and physiological systems as is evidenced in a long‐standing literature and consistent findings across species, populations, and experimental models. In humans and other animals, differential rearing conditions can affe...
Article
Several primate species have been shown to exhibit age-related changes in cognition, brain, and behavior. However, severe neurodegenerative illnesses, such as Alzheimer's disease (AD), were once thought to be uniquely human. Recently, some chimpanzees naturally were documented to develop both neurofibrillary tangles and amyloid plaques, the main ch...
Article
Individual differences in sulcal variation within the anterior and mid-cingulate cortex of the human brain, particularly the presence or absence of a paracingulate sulcus (PCGS), are associated with various motor and cognitive processes. Recently, it has been reported that chimpanzees possess a PCGS, previously thought to be a unique feature of the...
Article
Behavioral management programs aim to enhance the welfare of animal subjects that participate in research, thereby enhancing our ability to conduct ethical research projects. Socialization strategies, environmental enrichment techniques, opportunities for subjects to voluntarily participate in research procedures, and the provision of Functionally...
Article
Full-text available
In humans, neutrophil to lymphocyte ratio (NLR) has been used as a clinical tool in diagnosis and/or prognosis of a variety of cancers and medical conditions, as well as in measuring physiological stress over time. Given the close phylogenetic relationship and physical similarities between humans and apes, NLR may similarly be a useful diagnostic t...
Article
Humans are distinctive in their dependence upon products of culture for survival, products that have evolved cumulatively over generations such that many cannot now be created by a single individual. Why the cultural capacity of humans appears unrivalled in the animal kingdom is a topic of ongoing debate. Here we explore whether innovation and/or s...
Preprint
Full-text available
Food-associated calls have attracted much research attention due to their potential to refer to discovered food in a word-like manner. Nevertheless, their effect on receiver behavior remains unclear for many species. While some studies suggest that food-associated calls attract other foragers, other studies indicate that they repel others. We condu...
Article
Chimpanzees are the species most closely related to humans, yet age‐related changes in brain and cognition remain poorly understood. The lack of studies on age‐related changes in cognition in chimpanzees is particularly unfortunate in light of the recent evidence demonstrating that this species naturally develops Alzheimer's disease (AD) neuropatho...
Article
Full-text available
The ability to track syntactic relationships between words, particularly over distances ("nonadjacent dependencies"), is a critical faculty underpinning human language, although its evolutionary origins remain poorly understood. While some monkey species are reported to process auditory nonadjacent dependencies, comparative data from apes are missi...
Article
The human corpus callosum exhibits substantial atrophy in old age, which is stronger than what would be predicted from parallel changes in overall brain anatomy. To date, however, it has not been conclusively established whether this accentuated decline represents a common feature of brain aging across species, or whether it is a specific character...
Preprint
Full-text available
Once considered a hallmark of human uniqueness, brain asymmetry has emerged as a feature widely shared with other mammals, including chimpanzees, one of our closest living relatives. Most notable has been the discovery of asymmetries in homologs of cortical language areas in apes, particularly in the planum temporale (PT), considered a central node...
Article
Full-text available
Personality factors analogous to the Big Five observed in humans are present in the great apes. However, few studies have examined the long-term stability of great ape personality, particularly using factor-based personality instruments. Here, we assessed overall group, and individual-level, stability of chimpanzee personality by collecting ratings...
Article
Full-text available
Once considered a hallmark of human uniqueness, brain asymmetry has emerged as a feature shared with several other species, including chimpanzees, one of our closest living relatives. Most notable has been the discovery of asymmetries in homologues of cortical language areas in apes, particularly in the planum temporale (PT), considered a central n...
Preprint
Full-text available
The human corpus callosum exhibits substantial atrophy in old age, which is stronger than what would be predicted from parallel changes in overall brain anatomy. To date, however, it has not been conclusively established whether this accentuated decline represents a common feature of brain aging across species, or whether it is a specific character...
Article
Eye gaze is widespread in nonhuman primate taxa and important for social cognition and communicative signaling. Bonobos and chimpanzees, two closely related primate species, differ in social organization, behavior, and cognition. Chimpanzees' eye gaze and gaze following has been studied extensively, whereas less is known about bonobos' eye gaze. To...
Article
Obesity is a problem in captive chimpanzee colonies that can lead to increased risk for disease; therefore, implementation of effective weight management strategies is imperative. To properly implement a weight management program, captive managers should be able to noninvasively identify and assess overweight or obese individuals. Traditional means...
Article
Full-text available
Mutual eye gaze plays an important role in primate social development and communication. In the current study, we examined the underlying experiential, genetic, and neuroanatomical basis of mutual eye gaze variation in adult captive chimpanzees. A multivariate analysis of variance revealed a significant rearing effect on bout length, with human-rea...
Article
Full-text available
Across the animal kingdom, males tend to exhibit more behavioural and morphological variability than females, consistent with the 'greater male variability hypothesis'. This may reflect multiple mechanisms operating at different levels, including selective mechanisms that produce and maintain variation, extended male development, and X chromosome e...
Preprint
In humans, neutrophil to lymphocyte ratio (NLR) has been used as a clinical tool in diagnosis and/or prognosis of a variety of cancers and medical conditions, as well as in measuring physiological stress over time. Given the close phylogenetic relationship and physical similarities between humans and apes, NLR may similarly be a useful diagnostic t...
Preprint
Chimpanzees are the species most closely related to humans yet age-related changes in brain and cognition remain poorly understood. The lack of studies on age-related changes in cognition in chimpanzees is particularly unfortunate in light of the recent evidence demonstrating that this species naturally develops Alzheimer's disease (AD) neuropathol...
Preprint
Full-text available
Chimpanzees are among the closest living relatives to humans and, therefore, provide a crucial comparative model for investigating primate brain evolution. In recent years, human brain research has strongly benefited from enhanced computational models and image processing pipelines that could also improve data analyses in animals by using species-s...
Article
Due to advances in captive nonhuman primate (NHP) medical care, the number of geriatric chimpanzees (≥35-years old) is growing. With old age comes a variety of physical conditions, including arthritis, stroke, and mobility impairments. Programs aimed at enhancing the welfare of geriatric chimpanzees are now quite common, but there are few published...
Article
The vasopressin system has been implicated in the regulation of social behavior and cognition in humans, nonhuman primates and other social mammals. In chimpanzees, polymorphisms in the vasopressin V1a receptor gene (AVPR1A) have been associated with social dimensions of personality, as well as to responses to sociocommunicative cues and mirror sel...
Article
The population of NIH-owned or NIH-supported captive research chimpanzees is quickly becoming aged, and the 1998 NIH breeding moratorium has resulted in a skewed age distribution. As such, behavioral management programs aimed at refining the care of an aging captive chimpanzee population have become increasingly important. However, little research...
Article
Full-text available
NHP are a small, but critical, portion of the animals studied in research laboratories. Many NHP are imported or raised at one facility and subsequently moved to another facility for research purposes. To improve our understanding of the effects of transportation and relocation on the NHP immune system, to minimize potential confounds associated wi...
Poster
Full-text available
Evidence supporting the importance of snakes in primate evolution is growing, indicating that primates are specially adapted to detect snakes and that certain snake-related characteristics attract and hold our attention. However, there are few studies that compare primates’ reactions to snakes in comparison to other animals that are taxonomically c...
Poster
Full-text available
Vasopressin is a neuropeptide that regulates within- and between-species variation of social behavior among mammals. Previous studies in chimpanzees have found that polymorphisms in the vasopressin V1a receptor gene, AVPR1A, are associated with different dimensions of personality and measures of social cognition. For example, the minor allele is as...
Article
It has been hypothesized that the evolution of tool use may have served as a preadaptation for the emergence of left hemispheric specialization in motor skill in humans. Here, we tested for intermanual differences in performance on a tool use task in a sample of 206 captive chimpanzees in relation to their sex, age, and hand preference. In addition...
Article
Studying genetic mechanisms underlying primate brain morphology can provide insight into the evolution of human brain structure and cognition. In humans, loss‐of‐function mutations in the gene coding for ASPM (Abnormal Spindle Microtubule Assembly) have been associated with primary microcephaly, which is defined by a significantly reduced brain vol...
Article
Investigations of behavioral lateralization in nonhuman primates yield important insights into brain–behavior relationships. In turn, they provide clues about both proximal and distal factors that shape the development and expression of association between motor asymmetries and underlying neural substrates. Nonhuman primates afford unique comparati...
Article
Serotonin is a neurotransmitter that plays an important role in regulating behavior and personality in humans and other mammals. Polymorphisms in genes coding for the serotonin receptor subtype 1A (HTR1A), the serotonin transporter (SLC6A4), and the serotonin degrading enzyme monoamine oxidase A (MAOA) are associated with anxiety, impulsivity, and...
Article
Full-text available
Chimpanzees demand specialized housing and care and the highest degree of attention to animal welfare. The current project used a survey method to collate information on chimpanzee housing and behavioral indices of welfare across all 6 of the chimpanzee research facilities in the United States. Data were compiled on 701 chimpanzees ranging from 2 t...
Article
Full-text available
Neurons with histopathological changes consistent with granulovacuolar degeneration (GVD) were found in brain sections from aged cynomolgus monkeys (Macaca fascicularis) with clinical and pathological signs of cognitive aging. To our knowledge, this is the first reported description of GVD in non-human primates. GVD-like lesions were found also in...
Article
Voluntary participation in behavioural studies offers several scientific, management, and welfare benefits to non-human primates (NHPs). Aside from the scientific benefit of increased understanding of NHP cognition, sociality, and behaviour derived from noninvasive behavioural studies, participation itself has the potential to provide functional si...
Article
Full-text available
Games derived from experimental economics can be used to directly compare decision-making behavior across primate species, including humans. For example, the use of coordination games, such as the Assurance game, has shown that a variety of primate species can coordinate; however, the mechanism by which they do so appears to differ across species....
Article
Full-text available
Games from experimental economics have provided insights into the evolutionary roots of social decision making in primates and other species. Multiple primate species' abilities to cooperate, coordinate and anti-coordinate have been tested utilizing variants of these simple games. Past research, however, has focused on species known to cooperate an...
Article
The National Institutes of Health and the Association of Zoos and Aquariums recommend that captive chimpanzees be housed in multi-male, multi-female, age-diverse groups of no less than seven individuals. These recommendations are rooted in the idea that captive chimpanzee groups should be modeled after free-ranging, wild, fission-fusion chimpanzee...
Article
Nonhuman primates, and great apes in particular, possess a variety of cognitive abilities thought to underlie human brain and cognitive evolution, most notably, the manufacture and use of tools. In a relatively large sample (N = 226) of captive chimpanzees (Pan troglodytes) for whom pedigrees are well known, the overarching aim of the current study...
Article
Full-text available
Studies of transmission biases in social learning have greatly informed our understanding of how behaviour patterns may diffuse through animal populations, yet within-species inter-individual variation in social information use has received little attention and remains poorly understood. We have addressed this question by examining individual perfo...
Poster
Full-text available
Abstract: Primates typically react quickly and cautiously to snakes. However, it is not clear which features of snakes elicit avoidance once a possible snake has been detected. We conducted three experiments in which we assessed reactions to snake models by captive rhesus monkeys. In each experiment, at least 12 groups of 3-10 indoor/outdoor-housed...
Article
In an effort to enhance welfare, behavioural management continually refines methods of non-human primate (NHP) care. Chimpanzees (Pan troglodytes) are one of the most cognitively complex captive NHPs and they have been observed to self-medicate in the wild. The population of captive chimpanzees in the US is aged (due to a breeding moratorium instit...
Article
Cumulative culture is rare, if not altogether absent in nonhuman species. At the foundation of cumulative learning is the ability to modify, relinquish, or build upon previous behaviors flexibly to make them more productive or efficient. Within the primate literature, a failure to optimize solutions in this way is often proposed to derive from low-...
Article
A converging literature has revealed the existence of a set of largely consistent, hierarchically organized personality traits, that is broader traits are able to be differentiated into more fine-grained traits, in both humans and chimpanzees. Despite recent work suggesting a neural basis to personality in chimpanzees, little is known with regard t...
Article
Full-text available
How animal communities arrive at homogeneous behavioural preferences is a central question for studies of cultural evolution. Here, we investigated whether chimpanzees (Pan troglodytes) would relinquish a pre-existing behaviour to adopt an alternative demonstrated by an overwhelming majority of group mates; in other words, whether chimpanzees behav...
Chapter
Environmental enrichment is an integral part of animal care practices. Enrichment generally refers to items we provide to the animals to support their behavioral needs. It provides a way to functionally simulate the natural environment of captive animals, in an effort to increase opportunities for the expression of species-specific behaviors and de...
Article
Full-text available
Nonhuman primates from domestic sources constitute a small, but critical, proportion of animals studied in research laboratories. Many of these nonhuman primates are raised at one facility and subsequently transported/relocated to another facility for research purposes. We examined the effects of transport, relocation, and acclimation on the phenot...
Article
Full-text available
Various non-human animal species have been shown to exhibit behavioural traditions. Importantly, this research has been guided by what we know of human culture, and the question of whether animal cultures may be homologous or analogous to our own culture. In this paper, we assess whether models of human cultural transmission are relevant to underst...
Conference Paper
Behavioral assessment is an essential element of chimpanzee care. Behavioral data were compiled from four chimpanzee laboratory facilities (N=522; 286 females, 236 males) using differing methods of assessment including quantitative data collection, animal records and observations by behavioral management staff. The subjects were 46.4% mother-reared...
Conference Paper
Primadomes™ and corrals, two types of housing options available to captive chimpanzees, differ in several physical features, including closed (primadomes™) or open (corrals) tops, mesh (primadomes™) or concrete (corrals) walls, and available space per animal (142 ft2/individual in primadomes™; 516 ft2/individual in corrals). Our group has produced...
Article
Full-text available
Vasopressin is a neuropeptide known to be associated with the development and evolution of complex socio-emotional behaviors including those relevant to psychopathic personality. In both humans and chimpanzees, recent research suggests a strong genetic contribution to individual variation in psychopathic traits. To date, however, little is known co...