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Abstract Background Great apes are a global conservation concern, with anthropogenic pressures threatening their survival. Genetic analysis can be used to assess the effects of reduced population sizes and the effectiveness of conservation measures. In humans, autosomal short tandem repeats (aSTRs) are widely used in population genetics and for forensic individual identification and kinship testing. Traditionally, genotyping is length-based via capillary electrophoresis (CE), but there is an increasing move to direct analysis by massively parallel sequencing (MPS). An example is the ForenSeq DNA Signature Prep Kit, which amplifies multiple loci including 27 aSTRs, prior to sequencing via Illumina technology. Here we assess the applicability of this human-based kit in African great apes. We ask whether cross-species genotyping of the orthologs of these loci can provide both individual and (sub)species identification. Results The ForenSeq kit was used to amplify and sequence aSTRs in 52 individuals (14 chimpanzees; 4 bonobos; 16 western lowland, 6 eastern lowland, and 12 mountain gorillas). The orthologs of 24/27 human aSTRs amplified across species, and a core set of thirteen loci could be genotyped in all individuals. Genotypes were individually and (sub)species identifying. Both allelic diversity and the power to discriminate (sub)species were greater when considering STR sequences rather than allele lengths. Comparing human and African great-ape STR sequences with an orangutan outgroup showed general conservation of repeat types and allele size ranges. Variation in repeat array structures and a weak relationship with the known phylogeny suggests stochastic origins of mutations giving rise to diverse imperfect repeat arrays. Interruptions within long repeat arrays in African great apes do not appear to reduce allelic diversity. Conclusions Orthologs of most human aSTRs in the ForenSeq DNA Signature Prep Kit can be analysed in African great apes. Primer redesign would reduce observed variability in amplification across some loci. MPS of the orthologs of human loci provides better resolution for both individual and (sub)species identification in great apes than standard CE-based approaches, and has the further advantage that there is no need to limit the number and size ranges of analysed loci.

Extant great apes are characterized by a wide range of locomotor, postural and manipulative behaviours that each require the limbs to be used in different ways. In addition to external bone morphology, comparative investigation of trabecular bone, which (re‐)models to reflect loads incurred during life, can provide novel insights into bone functional adaptation. Here, we use canonical holistic morphometric analysis (cHMA) to analyse the trabecular morphology in the distal femoral epiphysis of Homo sapiens (n = 26), Gorilla gorilla (n = 14), Pan troglodytes (n = 15) and Pongo sp. (n = 9). We test two predictions: (1) that differing locomotor behaviours will be reflected in differing trabecular architecture of the distal femur across Homo, Pan, Gorilla and Pongo; (2) that trabecular architecture will significantly differ between male and female Gorilla due to their different levels of arboreality but not between male and female Pan or Homo based on previous studies of locomotor behaviours. Results indicate that trabecular architecture differs among extant great apes based on their locomotor repertoires. The relative bone volume and degree of anisotropy patterns found reflect habitual use of extended knee postures during bipedalism in Homo, and habitual use of flexed knee posture during terrestrial and arboreal locomotion in Pan and Gorilla. Trabecular architecture in Pongo is consistent with a highly mobile knee joint that may vary in posture from extension to full flexion. Within Gorilla, trabecular architecture suggests a different loading of knee in extension/flexion between females and males, but no sex differences were found in Pan or Homo, supporting our predictions. Inter‐ and intra‐specific variation in trabecular architecture of distal femur provides a comparative context to interpret knee postures and, in turn, locomotor behaviours in fossil hominins. [ABSTRACT FROM AUTHOR]

Reports of primates being able to recognise familiar humans are rare in the literature and tend to be regarded as anecdotal. The COVID-19 pandemic created two unique conditions facilitating the observation of spontaneous face recognition in zoo apes: i) lengthy gaps in contact with human visitors due to lockdowns and zoo closures, and ii) the wearing of face masks obscuring at least half the face of familiar individuals. Here, I report on the historical context of the familiarity between a primatologist and individual apes of two species, how those apes consistently showed recognition of this particular human over a time span of up to thirty years, how facial recognition was extended to family members, and how recognition persisted even when a significant portion of the face was obscured by a mask. This constitutes, to my knowledge, the first documented cases of recognition of familiar human faces changed by time and COVID-19 face masks in two great ape species. Although based on just two individuals, the documentation of this ability is important because it arose in a more naturalistic and spontaneous context compared to typical face processing research in which primates are tested with experimental stimuli in a laboratory setting. Implications for face processing theory and applications for the therapeutic utility of faces are discussed. These observations provide insight into the evolutionary origins of face recognition and, sitting at the interface of science and society, are of interest to a wide audience.

Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve. [ABSTRACT FROM AUTHOR]

Coronaviruses (CoVs, Coronaviridae) are a diverse group of viruses that infect mammals, birds, and fish. Seven CoVs infect humans, among which Severe Acute Respiratory Syndrome CoVs-1 and -2 and Middle East respiratory syndrome CoVs have shown how they can impact global health and the economy. Their spillover from bats-the natural reservoir-to humans has required intermediary hosts. Prevention requires that active surveillance be conducted on animals. Today, there is no data concerning the genetic diversity of CoVs naturally circulating in wild primates. This study aimed to screen wild great apes and mandrills in Gabon for CoVs. A total of 229 faecal samples of great apes and mandrills collected from 2009 to 2012 in forests and national parks were used for the detection of CoVs by nested PCR using primers targeting a conserved region of the RNA-dependent RNA polymerase. While all samples were negative, this lack of detection could be related to sample size, the transient nature of the infection, or because faecal samples are not suitable for detecting CoVs in primates. A longitudinal study should be performed and other non-invasive methods used to collect respiratory samples to better evaluate the circulation of CoVs in these primates. [ABSTRACT FROM AUTHOR]

The majority of bite wounds that we encounter in the emergency department are caused by dogs, cats and humans, but bite injuries can be caused by a variety of animals. Here, we describe a case of bite wound and trauma caused by a large gorilla (Western lowland gorilla) weighing over 170 kg. Gorilla bites are rare, and the patient had an open fracture of the right distal radioulna in addition to multiple bite wounds. Treatment required careful consideration of gorilla antigenicity and a literature review to guide the selection of appropriate antimicrobial agents. Furthermore, trauma inflicted by large animals tends to require systemic traumatological screening, and patients can develop acute stress disorder because of a fear of being attacked again; therefore, early psychiatric intervention is important.

Bone loss and heightened fracture risk are common conditions associated with ageing in modern human populations and have been attributed to both hormonal and other metabolic and behavioural changes. To what extent these age-related trends are specific to modern humans or generally characteristic of natural populations of other taxa is not clear. In this study, we use computed tomography to examine age changes in long bone and vertebral structural properties of 34 wild-adult Virunga mountain gorillas (Gorilla beringei beringei) whose skeletons were recovered from natural accumulations. Chronological ages were known or estimated from sample-specific dental wear formulae and ranged between 11 and 43 years. Gorillas show some of the same characteristics of skeletal ageing as modern humans, including endosteal and some periosteal expansion. However, unlike in humans, there is no decline in cortical or trabecular bone density, or in combined geometric-density measures of strength, nor do females show accelerated bone loss later in life. We attribute these differences to the lack of an extended post-reproductive period in gorillas, which provides protection against bone resorption. Increases in age-related fractures (osteoporosis) in modern humans may be a combined effect of an extended lifespan and lower activity levels earlier in life. This article is part of the theme issue 'Evolution of the primate ageing process'.

Using methods comparable to those used previously to test closely-related taxa (Pan troglodytes and Macaca mulatta), our aim was to better understand how gorillas (Gorilla gorilla gorilla) and Japanese macaques (M. fuscata) learn sequences. Using a disappearing-type simultaneous chain, we trained five gorillas and eight macaques on a two-item list of colored stimuli presented via touchscreens. There was no difference across species in the number of trials required to learn the two-item list. We added a third item to the list as each subject reached criterion. We then analyzed the subjects’ first 30 trials with the three-item list and found that the rate of successfully sequencing the list varied by subject but not by species. In their first 30 trials of the three-item list, subjects selected the second item correctly only at chance, suggesting they had only encoded the first symbol when learning the two-item list. One gorilla, tested on longer sequences, showed similar responses: when first presented with a newly-lengthened list, he only selected the penultimate item at chance levels. Thus, the primates’ errors with newly-lengthened lists is suggestive of the chaining theory of learning. These results highlight similarities in list learning of these two distantly-related primate species as well as the clear intra-species variation in learning.

Whether or not primates are behaviorally affected by the presence of visitors in a zoo setting is a question of great relevance to zoo animal well-being. The situation imposed by the COVID-19 pandemic provided an unusual opportunity to examine how the absence of visitors impacts behavior. We took advantage of this opportunity to study the behavior of a gorilla troop during periods of no-visitors compared to our long-term database on gorilla behavior during normal zoo operations. While there were notable individual differences in response to visitors, we found no significant relationship between presence of visitors and behavior. These results suggest that the presence of visitors does not have a significant impact on behavior and well-being of zoo-housed gorillas.

Coronaviruses (CoVs, Coronaviridae) are a diverse group of viruses that infect mammals, birds, and fish. Seven CoVs infect humans, among which Severe Acute Respiratory Syndrome CoVs-1 and -2 and Middle East respiratory syndrome CoVs have shown how they can impact global health and the economy. Their spillover from bats-the natural reservoir-to humans has required intermediary hosts. Prevention requires that active surveillance be conducted on animals. Today, there is no data concerning the genetic diversity of CoVs naturally circulating in wild primates. This study aimed to screen wild great apes and mandrills in Gabon for CoVs. A total of 229 faecal samples of great apes and mandrills collected from 2009 to 2012 in forests and national parks were used for the detection of CoVs by nested PCR using primers targeting a conserved region of the RNA-dependent RNA polymerase. While all samples were negative, this lack of detection could be related to sample size, the transient nature of the infection, or because faecal samples are not suitable for detecting CoVs in primates. A longitudinal study should be performed and other non-invasive methods used to collect respiratory samples to better evaluate the circulation of CoVs in these primates.

Great apes are threatened by many factors including habitat loss, forest degradation and disease. Despite the improved understanding of the distribution of gorillas in Cameroon, there is a lack of fine‐scale knowledge about their habitat use. We used the Kernel Density Estimate method combined with grid cell counting to assess gorilla distribution, habitat use and human disturbance on one of the least studied gorilla populations in Cameroon. Proportions of different habitat types in the landscape were quantified using classification and regression tree approach applied to Landsat‐8 and digital elevation model data. We found that the distribution of gorillas was restricted to the central band of the site (~22 km2). Although the area was dominated by mature forest, the goodness‐of‐fit test showed that gorillas used grassland areas more frequently. Intensive human activities were noted across the gorilla range, with used cartridge shells being the most evidence hunting sign. Our results can be used to guide conservation and sustainable development stakeholder decisions in the area. With increasing anthropogenic threats throughout the landscape, we recommend the implementation of noninvasive research activities focusing on threat monitoring, nesting and dietary ecology, and the promotion of community‐led conservation initiatives to reduce pressure on the gorilla habitat. [ABSTRACT FROM AUTHOR]

Host-associated microbiomes are essential for a multitude of biological processes. Placed at the contact zone between external and internal environments, the little-studied oral microbiome has important roles in host physiology and health. Here, we investigate the roles of host evolutionary relationships and ecology in shaping the oral microbiome in three closely related gorilla subspecies (mountain, Grauer's, and western lowland gorillas) using shotgun metagenomics of 46 museum-preserved dental calculus samples. We find that the oral microbiomes of mountain gorillas are functionally and taxonomically distinct from the other two subspecies, despite close evolutionary relationships and geographic proximity with Grauer's gorillas. Grauer's gorillas show intermediate bacterial taxonomic and functional, and dietary profiles. Altitudinal differences in gorilla subspecies ranges appear to explain these patterns, suggesting a close connection between dental calculus microbiomes and the environment, likely mediated through diet. This is further supported by the presence of gorilla subspecies-specific phyllosphere/rhizosphere taxa in the oral microbiome. Mountain gorillas show a high abundance of nitrate-reducing oral taxa, which may promote adaptation to a high-altitude lifestyle by modulating blood pressure. Our results suggest that ecology, rather than evolutionary relationships and geographic distribution, shape the oral microbiome in these closely related species. [ABSTRACT FROM AUTHOR]

(1) Background: Terrestrial mammals in protected areas have been identified as a potential source of antimicrobial-resistant bacteria. Studies on antimicrobial resistance in gorillas have already been conducted. Thus, this study aimed to describe the phylogroups, pathotypes and prevalence of antimicrobial resistance of Escherichia coli isolated from western lowland gorilla's faeces living in MDNP. (2) Materials and Methods: Ninety-six faecal samples were collected from western lowland gorillas (Gorilla gorilla gorilla) during daily monitoring in the MDNP. Sixty-four E. coli isolates were obtained and screened for phylogenetic and pathotype group genes by polymerase chain reaction (PCR) after DNA extraction. In addition, antimicrobial susceptibility was determined by the disk diffusion method on Mueller Hinton agar. (3) Results: Sixty-four (64%) isolates of E. coli were obtained from samples. A high level of resistance to the beta-lactam family, a moderate rate for fluoroquinolone and a low rate for aminoglycoside was obtained. All E. coli isolates were positive in phylogroup PCR with a predominance of A (69% ± 11.36%), followed by B2 (20% ± 19.89%) and B1 (10% ± 8.90%) and low prevalence for D (1% ± 3.04%). In addition, twenty E. coli isolates (31%) were positive for pathotype PCR, such as EPEC (85% ± 10.82%) and EPEC/EHEC (15% ± 5.18%) that were obtained in this study. The majority of these MDR E. coli (DECs) belonged to phylogenetic group A, followed by MDR E. coli (DECs) belonging to group B2. (4) Conclusion: This study is the first description of MDR E. coli (DECs) assigned to phylogroup A in western lowland gorillas from the MDNP in Gabon. Thus, wild gorillas in MDNP could be considered as asymptomatic carriers of potential pathogenic MDR E. coli (DECs) that may present a potential risk to human health. [ABSTRACT FROM AUTHOR]

Abstract Background Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. Besides human fatalities, gorillas and chimpanzees have also succumbed to the fatal virus. The 2004 outbreak at the Odzala-Kokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. Here, we explore the immediate genetic impact of the Ebola outbreak in the western lowland gorilla population. Results Associations with survivorship were evaluated by utilizing DNA obtained from fecal samples from 16 gorilla individuals declared missing after the outbreak (non-survivors) and 15 individuals observed before and after the epidemic (survivors). We used a target enrichment approach to capture the sequences of 123 genes previously associated with immunology and Ebola virus resistance and additionally analyzed the gut microbiome which could influence the survival after an infection. Our results indicate no changes in the population genetic diversity before and after the Ebola outbreak, and no significant differences in microbial community composition between survivors and non-survivors. However, and despite the low power for an association analysis, we do detect six nominally significant missense mutations in four genes that might be candidate variants associated with an increased chance of survival. Conclusion This study offers the first insight to the genetics of a wild great ape population before and after an Ebola outbreak using target capture experiments from fecal samples, and presents a list of candidate loci that may have facilitated their survival.

Gorillas are among the most charismatic and well-researched species on the planet, yet their role as zoogeomorphic agents has gone largely overlooked. Knowledge on how gorillas contribute to landscape formation and decay is vital for future conservation planning and habitat suitability modeling. The purpose of this study is to conduct a content analysis of literature to identify gorilla zoogeomorphic activity and to aggregate and organize data into nine zoogeomorphic categories. Data obtained was used to provide a qualitative and quantitative summary of inter/intra-specific gorilla zoogeomorphic activity, and the extent of literature available on the subject. Categories of gorilla zoogeomorphic activity include: (1) soil scratching and (2) soil scraping of the forest floor; (3) excavating chambers and holes; (4) bare/semi-bare soil nest site building; (5) hand/knuckle and footprints; (6) excavating insect mounds; (7) tool use and associated geomorphic implications (8) trunk uprooting, and (9) trampling. All four gorilla sub-species (G. gorilla, G. beringei, G. graueri, G. dielhi) were represented in the literature with evidence presented from nine countries in central Africa. Nest construction, mound disturbance, and excavated surface depressions were most frequently documented. Nests and mounds each made up 22 percent and excavated holes encompassed 16 percent of the literature. Soil-scraping, tool use, and trunk uprooting were poorly represented making up 6 percent, 1 percent, and 2 percent of the total literature, respectively.

When we consider the preservation of the animal body in natural history displays, we primarily think of techniques such as taxidermy or the mounting of a skeletal anatomy. Animal death masks are, by contrast, almost completely unstudied. Although casting has been predominantly understood as a technique for preserving the human face, non-humans have also had their faces captured by the casting of a death mask, and the resultant plaster used for a variety of purposes, from the creation of an accurate taxidermy mount, to featuring as a display object in its own right. ‘Animal Death Masks’ examines three case studies in which death masks play an integral role, all of which feature male gorillas kept in city zoos who grew to be local celebrities and were preserved for display in their regional museum, and each of whom had a cast taken of their face after death. This article argues that animal death masks materialize the distorted boundaries present in museum primate narratives: between indexical representations and artistic portraits, endangered animals and celebrity, conservation and preservation.

Whether or not primates are behaviorally affected by the presence of visitors in a zoo setting is a question of great relevance to zoo animal well-being. The situation imposed by the COVID-19 pandemic provided an unusual opportunity to examine how the absence of visitors impacts behavior. We took advantage of this opportunity to study the behavior of a gorilla troop during periods of no-visitors compared to our long-term database on gorilla behavior during normal zoo operations. While there were notable individual differences in response to visitors, we found no significant relationship between presence of visitors and behavior. These results suggest that the presence of visitors does not have a significant impact on behavior and well-being of zoo-housed gorillas. [ABSTRACT FROM AUTHOR]

Mirror self-recognition (MSR), widely regarded as an indicator of self-awareness, has not been demonstrated consistently in gorillas. We aimed to examine this issue by setting out a method to evaluate gorilla self-recognition studies that is objective, quantifiable, and easy to replicate. Using Suarez and Gallup's (J Hum Evol 10:175–183, 1981) study as a reference point, we drew up a list of 15 methodological criteria and assigned scores to all published studies of gorilla MSR for both methodology and outcomes. Key features of studies finding both mark-directed and spontaneous self-directed responses included visually inaccessible marks, controls for tactile and olfactory cues, subjects who were at least 5 years old, and clearly distinguishing between responses in front of versus away from the mirror. Additional important criteria include videotaping the tests, having more than one subject, subjects with adequate social rearing, reporting post-marking observations with mirror absent, and giving mirror exposure in a social versus individual setting. Our prediction that MSR studies would obtain progressively higher scores as procedures and behavioural coding practices improved over time was supported for methods, but not for outcomes. These findings illustrate that methodological rigour does not guarantee stronger evidence of self-recognition in gorillas; methodological differences alone do not explain the inconsistent evidence for MSR in gorillas. By implication, it might be suggested that, in general, gorillas do not show compelling evidence of MSR. We advocate that future MSR studies incorporate the same criteria to optimize the quality of attempts to clarify the self-recognition abilities of gorillas as well as other species. [ABSTRACT FROM AUTHOR]

Simple Summary: We presented three adult male zoo-housed gorillas (Gorilla gorilla gorilla) with a modified emotional Stroop task on a computer touchscreen as a way to assess gorillas' attentional shift for positively versus negatively valenced items. The gorillas learned to respond to a blue border and to withhold responding to a yellow border. Images of items assumed to have a positive or negative valence for the gorillas were placed within the borders. As predicted, gorillas touched the reinforced blue border more slowly when 'negative' images appeared within the blue border, compared to when 'positive' images appeared within the yellow border. However, gorillas' accuracy did not vary as a function of which images appeared within the blue border, possibly because of the high levels of performance on all trials. These results validate the procedure to some degree for assessing the emotional valence of familiar stimuli. We adapted the emotional Stroop task developed for primates to test whether gorillas would show response slowing for images of 'negative' compared to images of 'positive' items placed within previously reinforced borders. Three zoo-housed male gorillas participated in six phases of an emotional Stroop paradigm. In Phase One, they learned to select blue borders over yellow borders in a forced choice task presented on the touchscreen. In Phase Two, neutral yellow or blue two-dimensional shapes were placed within the borders. On congruent trials, blue images were presented within both blue and yellow borders. On incongruent trials, yellow images were placed within both blue and yellow borders. We continued to use these trials as control trials in subsequent phases. We predicted that response latencies would be slower and accuracy would be lower on incongruent trials. Although the gorillas responded more quickly to incongruent trials, in contrast to predictions, they were more accurate on congruent trials, consistent with predictions. Therefore, we proceeded with Phase Three in which photographs of images assumed to have positive and negative valences for the gorillas were placed within the borders. On test trials, the same positive or negative image was placed within both borders. In Phase Four, a positive image was paired with a negative image on each trial and the positive image appeared in either the blue (congruent trials) or yellow border (incongruent trials). Phases Five and Six replicated Phases Three and Four with images of novel positive and negative items. The gorillas responded more quickly on congruent trials compared to incongruent trials on test trials but not on control trials throughout Phases 3–6. These findings provide some validation for the emotional Stroop task to test attentional shift with emotionally valenced items. [ABSTRACT FROM AUTHOR]

Since the Symposium on Mycobacterial Infections of Zoo Animals held at the National Zoological Park, Smithsonian Institution in 1976, our understanding of tuberculosis (TB) in non-domestic animals has greatly expanded. Throughout the past decades, this knowledge has resulted in improved zoo-habitats and facilities design, stricter biosecurity measures, and advanced diagnostic methods, including molecular techniques, that have significantly decreased the number of clinical disease caused by Mycobacterium tuberculosis in apes under human care settings. In the other hand, exponential growth of human populations has led to human encroachment in wildlife habitat which has resulted in increased inter-species contact and recurrent conflict between humans and wild animals. Although it is widely accepted that non-human primates are susceptible to M. tb infection, opinions differ with regard to the susceptibility to develop disease amongst different taxa. Specifically, some authors suggest that African apes are less susceptible to clinical tuberculosis than other species of primates. The aim of this review article is to evaluate the current scientific literature to determine the actual health impact of disease caused by Mycobacterium tuberculosis and more specifically Mycobacterium tuberculosis sensu stricto in African apes. The literature review included literature databases: Web of Science, Pubmed, Scopus, Wiley, Springer and Science direct, without temporal limit and proceedings of annual conferences in the field of wildlife health. Our general inclusion criteria included information about serological, molecular, pathological (macroscopic and/or microscopic), and clinical evidence of TB in African apes; while our, our more stringent inclusion selection criteria required that in addition to a gross pathology, a molecular test confirmed Mycobacterium tuberculosis sensu stricto as the cause of disease or death. We identified eleven reports of tuberculosis in African apes; of those, only four reports met the more stringent selection criteria that confirmed M. tb sensu stricto in six individuals. All reports that confirmed M. tb sensu stricto originated from zoological collections. Our review suggests that there is little evidence of disease or mortality caused by M. tb in the different species of African apes both under human care and free ranging populations. Additional studies are needed in free-ranging, semi-captive populations (sanctuaries) and animals under human care (zoos and rescue centers) to definitely conclude that this mycobacteria has a limited health effect in African ape species. [ABSTRACT FROM AUTHOR]

Primates’ food preferences are typically assessed under conditions of certainty. To increase ecological validity, and to explore primates’ decision making from a comparative perspective, we tested three primate species (Pan troglodytes, Gorilla gorilla gorilla, Macaca fuscata) (N = 18) in two food-preference tests that created different conditions of uncertainty. In the first, we showed subjects pairs of photographs of six foods in a randomized manner within each session, so subjects could not predict the next pairing and had to respond in accordance with their preferences. We found individual differences in subjects’ preference and differences in six subjects’ preferences when comparing their selections in this test to selections made when trials were blocked by food pairing (tested previously: Huskisson et al., 2020). In in each trial of the second test we paired the food stimuli with a ‘chance’ symbol, representing a random reward of one of the six foods. Across species, each subject’s propensity to select chance over the known food varied by food type: when the known option was highly preferred, subjects were less likely to select the chance symbol. Additionally, 61.11% of the subjects’ rates of selecting foods in the first test showed a positive trend with the rates of selecting the same foods under conditions of uncertainty here; three of these subjects’ selection rates were significantly correlated between tests. Finally, if the food chimpanzees received for selecting the chance symbol was a preferred food, they were more likely to select chance again in the subsequent trial.

Gorillas are among the most charismatic and well-researched species on the planet, yet their role as zoogeomorphic agents has gone largely overlooked. Knowledge on how gorillas contribute to landscape formation and decay is vital for future conservation planning and habitat suitability modelling. The purpose of this study is to conduct a content analysis of literature to identify gorilla zoogeomorphic activity and to aggregate and organize data into nine zoogeomorphic categories. Data obtained was used to provide a qualitative and quantitative summary of inter/intra-specific gorilla zoogeomorphic activity, and the extent of literature available on the subject. Categories of gorilla zoogeomorphic activity include: (1) soil scratching and (2) soil scraping of the forest floor; (3) excavating chambers and holes; (4) bare/semi-bare soil nest site building; (5) hand/knuckle and footprints; (6) excavating insect mounds; (7) tool use and associated geomorphic implications (8) trunk uprooting, and (9) trampling. All four gorilla sub-species (G. gorilla, G. beringei, G. graueri, G. dielhi) were represented in the literature with evidence presented from nine countries in central Africa. Nest construction, mound disturbance, and excavated surface depressions were most frequently documented. Nests and mounds each made up 22 percent and excavated holes encompassed 16 percent of the literature. Soil-scraping, tool use, and trunk uprooting were poorly represented, making up 6 percent, 1 percent, and 2 percent of the total literature, respectively. [ABSTRACT FROM AUTHOR]

African apes engage in a distinct form of locomotion called knuckle‐walking, but there is much ambiguity as to when and how this locomotor behavior evolved. This study aims to elucidate potential differences in knuckle‐walking elbow posture and loading in African apes through the study of trabecular bone. Using a whole‐epiphysis approach, we quantified variation in the trabecular structure of the distal humerus of chimpanzees, western lowland gorillas, and mountain gorillas in comparison to orang‐utans, siamangs, and a sample of Old and New World monkeys. Results demonstrate differences in the distribution of trabecular bone within the distal humerus that are consistent across taxa that habitually use a flexed‐elbow posture in comparison to those that use an extended elbow during locomotion. Western lowland gorillas show an extended‐elbow pattern consistent with the straight forelimb position during knuckle‐walking, whereas chimpanzees show a flexed‐elbow pattern. Unexpectedly, mountain gorillas show an intermediate pattern between their western counterparts and chimpanzees. The differences found in elbow joint posture between chimpanzees and gorillas, and between gorilla species, point to diversification in the knuckle‐walking biomechanical strategies among African apes, which has implications in the debate regarding the locomotor behavior from which human bipedalism arose. [ABSTRACT FROM AUTHOR]

Background: Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. Besides human fatalities, gorillas and chimpanzees have also succumbed to the fatal virus. The 2004 outbreak at the Odzala-Kokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. Here, we explore the immediate genetic impact of the Ebola outbreak in the western lowland gorilla population. Results: Associations with survivorship were evaluated by utilizing DNA obtained from fecal samples from 16 gorilla individuals declared missing after the outbreak (non-survivors) and 15 individuals observed before and after the epidemic (survivors). We used a target enrichment approach to capture the sequences of 123 genes previously associated with immunology and Ebola virus resistance and additionally analyzed the gut microbiome which could influence the survival after an infection. Our results indicate no changes in the population genetic diversity before and after the Ebola outbreak, and no significant differences in microbial community composition between survivors and non-survivors. However, and despite the low power for an association analysis, we do detect six nominally significant missense mutations in four genes that might be candidate variants associated with an increased chance of survival. Conclusion: This study offers the first insight to the genetics of a wild great ape population before and after an Ebola outbreak using target capture experiments from fecal samples, and presents a list of candidate loci that may have facilitated their survival. [ABSTRACT FROM AUTHOR]

Aim: Modelling African great ape distribution has until now focused on current or past conditions, while future scenarios remain scarcely explored. Using an ensemble forecasting approach, we predicted changes in taxon‐specific distribution under future scenarios of climate, land use and human populations for (1) areas outside protected areas (PAs) only (assuming complete management effectiveness of PAs), (2) the entire study region and (3) interspecies range overlap. Location: Tropical Africa. Methods: We compiled occurrence data (n = 5,203) on African apes from the IUCN A.P.E.S. database and extracted relevant climate‐, habitat‐ and human‐related predictors representing current and future (2050) conditions to predict taxon‐specific range change under a best‐ and a worst‐case scenario, using ensemble forecasting. Results: The predictive performance of the models varied across taxa. Synergistic interactions between predictors are shaping African ape distribution, particularly human‐related variables. On average across taxa, a range decline of 50% is expected outside PAs under the best scenario if no dispersal occurs (61% in worst scenario). Otherwise, an 85% range reduction is predicted to occur across study regions (94% worst). However, range gains are predicted outside PAs if dispersal occurs (52% best, 21% worst), with a slight increase in gains expected across study regions (66% best, 24% worst). Moreover, more than half of range losses and gains are predicted to occur outside PAs where interspecific ranges overlap. Main Conclusions: Massive range decline is expected by 2050, but range gain is uncertain as African apes will not be able to occupy these new areas immediately due to their limited dispersal capacity, migration lag and ecological constraints. Given that most future range changes are predicted outside PAs, Africa's current PA network is likely to be insufficient for preserving suitable habitats and maintaining connected ape populations. Thus, conservation planners urgently need to integrate land use planning and climate change mitigation measures at all decision‐making levels both in range countries and abroad. [ABSTRACT FROM AUTHOR]

(1) Background: Terrestrial mammals in protected areas have been identified as a potential source of antimicrobial-resistant bacteria. Studies on antimicrobial resistance in gorillas have already been conducted. Thus, this study aimed to describe the phylogroups, pathotypes and prevalence of antimicrobial resistance of Escherichia coli isolated from western lowland gorilla’s faeces living in MDNP. (2) Materials and Methods: Ninety-six faecal samples were collected from western lowland gorillas (Gorilla gorilla gorilla) during daily monitoring in the MDNP. Sixty-four E. coli isolates were obtained and screened for phylogenetic and pathotype group genes by polymerase chain reaction (PCR) after DNA extraction. In addition, antimicrobial susceptibility was determined by the disk diffusion method on Mueller Hinton agar. (3) Results: Sixty-four (64%) isolates of E. coli were obtained from samples. A high level of resistance to the beta-lactam family, a moderate rate for fluoroquinolone and a low rate for aminoglycoside was obtained. All E. coli isolates were positive in phylogroup PCR with a predominance of A (69% ± 11.36%), followed by B2 (20% ± 19.89%) and B1 (10% ± 8.90%) and low prevalence for D (1% ± 3.04%). In addition, twenty E. coli isolates (31%) were positive for pathotype PCR, such as EPEC (85% ± 10.82%) and EPEC/EHEC (15% ± 5.18%) that were obtained in this study. The majority of these MDR E. coli (DECs) belonged to phylogenetic group A, followed by MDR E. coli (DECs) belonging to group B2. (4) Conclusion: This study is the first description of MDR E. coli (DECs) assigned to phylogroup A in western lowland gorillas from the MDNP in Gabon. Thus, wild gorillas in MDNP could be considered as asymptomatic carriers of potential pathogenic MDR E. coli (DECs) that may present a potential risk to human health.

Urban wildmeat consumption can contribute to significant declines in wildlife populations, ecosystem function, and food insecurity security. Describing types of individuals involved in illegal urban wildmeat trafficking can help distinguish ordinary citizens from members of criminal organizations and urban vs. rural dimensions of the activity. This research aimed to: (1) create and apply a typology for urban wildmeat traffickers and sellers; and (2) explore linkages between types of urban wildmeat traffickers and sellers. We used focus groups with experts in Republic of the Congo, February 2019 (N = 2, n = 7–10) to achieve objectives and focused on pangolins, great apes, and dwarf crocodiles. Participants generated risk rankings for each species, typology and city; data was encoded and indexed. Results illustrate heterogeneity in actors involved in the illegal supply chain. Business sideliner and trading charity trafficker types were associated with the highest total risk to wildlife trafficking. A similar pattern of divergence was detected for seller typologies; hidden and casual sellers were associated with the greatest total risk in Pointe Noire and Brazzaville, respectively. Differentiating but not stove piping stakeholders involved in urban wildmeat trafficking will help clarify stages of illegal supply chains as well and promote thinking about new sectors to involve in interventions and solutions, particularly in urban ecosystems thought to be outside the scope to wildlife crime.

We adapted the emotional Stroop task developed for primates to test whether gorillas would show response slowing for images of ‘negative’ compared to images of ‘positive’ items placed within previously reinforced borders. Three zoo-housed male gorillas participated in six phases of an emotional Stroop paradigm. In Phase One, they learned to select blue borders over yellow borders in a forced choice task presented on the touchscreen. In Phase Two, neutral yellow or blue two-dimensional shapes were placed within the borders. On congruent trials, blue images were presented within both blue and yellow borders. On incongruent trials, yellow images were placed within both blue and yellow borders. We continued to use these trials as control trials in subsequent phases. We predicted that response latencies would be slower and accuracy would be lower on incongruent trials. Although the gorillas responded more quickly to incongruent trials, in contrast to predictions, they were more accurate on congruent trials, consistent with predictions. Therefore, we proceeded with Phase Three in which photographs of images assumed to have positive and negative valences for the gorillas were placed within the borders. On test trials, the same positive or negative image was placed within both borders. In Phase Four, a positive image was paired with a negative image on each trial and the positive image appeared in either the blue (congruent trials) or yellow border (incongruent trials). Phases Five and Six replicated Phases Three and Four with images of novel positive and negative items. The gorillas responded more quickly on congruent trials compared to incongruent trials on test trials but not on control trials throughout Phases 3–6. These findings provide some validation for the emotional Stroop task to test attentional shift with emotionally valenced items.

Since the Symposium on Mycobacterial Infections of Zoo Animals held at the National Zoological Park, Smithsonian Institution in 1976, our understanding of tuberculosis (TB) in non-domestic animals has greatly expanded. Throughout the past decades, this knowledge has resulted in improved zoo-habitats and facilities design, stricter biosecurity measures, and advanced diagnostic methods, including molecular techniques, that have significantly decreased the number of clinical disease caused by Mycobacterium tuberculosis in apes under human care settings. In the other hand, exponential growth of human populations has led to human encroachment in wildlife habitat which has resulted in increased inter-species contact and recurrent conflict between humans and wild animals. Although it is widely accepted that non-human primates are susceptible to M. tb infection, opinions differ with regard to the susceptibility to develop disease amongst different taxa. Specifically, some authors suggest that African apes are less susceptible to clinical tuberculosis than other species of primates. The aim of this review article is to evaluate the current scientific literature to determine the actual health impact of disease caused by Mycobacterium tuberculosis and more specifically Mycobacterium tuberculosis sensu stricto in African apes. The literature review included literature databases: Web of Science, Pubmed, Scopus, Wiley, Springer and Science direct, without temporal limit and proceedings of annual conferences in the field of wildlife health. Our general inclusion criteria included information about serological, molecular, pathological (macroscopic and/or microscopic), and clinical evidence of TB in African apes; while our, our more stringent inclusion selection criteria required that in addition to a gross pathology, a molecular test confirmed Mycobacterium tuberculosis sensu stricto as the cause of disease or death. We identified eleven reports of tuberculosis in African apes; of those, only four reports met the more stringent selection criteria that confirmed M. tb sensu stricto in six individuals. All reports that confirmed M. tb sensu stricto originated from zoological collections. Our review suggests that there is little evidence of disease or mortality caused by M. tb in the different species of African apes both under human care and free ranging populations. Additional studies are needed in free-ranging, semi-captive populations (sanctuaries) and animals under human care (zoos and rescue centers) to definitely conclude that this mycobacteria has a limited health effect in African ape species.

Past Their Prime is a half-hour documentary about Colo— the oldest living gorilla in captivity — on her 55th birthday, and her place in the world of geriatric zoo animal care.             It’s winter at the Columbus Zoo in Columbus, Ohio. In the ape house elderly visitors browse slowly, wrapped in down jackets. Children run from exhibit to exhibit, pointing at the animals they see and announcing each one to their grandparents.Behind the glass, Colo, the stately matriarch of the groups peers back at the visitors from her solo room. She perks up when a camera flashes into view. But the camera’s gaze turns from Colo onto the adjacent room where 1-year old gorilla Nadami pesters her mother. And Colo returns to carefully picking at remnants of breakfast that remain on her enclosure floor.           The Columbus Zoo staff welcomed Colo on December 22, 1956. She was a household name, appearing in local papers as well as national publications that all announced the first gorilla born into captivity. From her first birthday through her 54th, visitors flocked to the zoo to celebrate another year of her life. Now, since reclaiming the title of “oldest living gorilla in captivity,” Colo’s staff look forward to celebrating another precious year of her life complete with presents, decorations, and a gorilla-friendly birthday cake.Geriatric gorillas, like Colo, often experience arthritis. Colo labors about her room on her wrists instead of her now-curled knuckles. Aging captive gorillas may also experience cardiac disease, dental decay, urinary tract infections, and constipation. For that, they’re fed prunes.As advances in medical care help the animals live longer lives, animal healthcare staffers look for creative and often familiar methods of care. On top of the veterinary care they already employ, the Columbus Zoo staff works with human doctors from the neighboring hospitals and researchers from Ohio State University to help inform their decisions. And not just for their gorillas.           Kulinda has a bit of a plaque problem. But Kulinda can’t go to just any dentist, she’d break the dentist’s chair. Aging rhinos in captivity, like Kulinda, have begun demonstrating dental issues that hadn’t previously appeared in the skulls of rhinos that lived in the wild. Harry Peachey, manager of the Pachyderm House at the zoo, says they believe the issues are due to a lack of coarse browse the animals would feed on in the wild. Finding enough browse to match what a rhino’s consumption is impractical in the Midwest. To combat the plaque, they brush their rhinos’ teeth.           The care of geriatrics extends throughout the park across species and regions of origin at the zoo. Dusty Lombardi, Vice President of Animal Care, remarks that their efforts have been fueled largely in part because of the care celebrity Colo receives, and the benefits they’ve seen as a result. “When you see the benefits for Colo,” she says, “you do it for the other animals.” And in the end Colo celebrates her birthday with all the pomp and circumstance befitting of a grand dame.

Background Individuals experiencing negative affect have shown response slowing, a longer latency to respond in relation to baseline, when presented with aversive stimuli. We assessed response slowing in three male gorillas housed in a bachelor group as a function of daytime and nighttime housing arrangements. Methods In both experiments, three gorillas were rewarded for touching a single image (baseline, non-threatening gorilla or threatening gorilla) on a touchscreen. In Experiment One, they completed 48 50-trial sessions across combinations of three nested daytime and three nighttime conditions. In Experiment Two, they completed eight 50-trial sessions with novel stimuli across two daytime conditions, which were nested within two nighttime conditions. Housing conditions represented different amounts of space and degree of choice. We predicted that the gorillas would show response slowing to threatening stimuli when space and choice were restricted. Results We did not observe response slowing in Experiment One, although daytime and nighttime conditions interacted to predict response latencies. The gorillas responded more slowly when they had access to indoors and outdoors overnight compared to when they were in their stalls or together in an indoor habitat, but only if they had been given access to both indoors and outdoors or locked in the indoor habitat the day before. In Experiment Two, the gorillas did show response slowing to threatening stimuli, but this pattern did not interact with housing conditions. Our results, although limited by a small sample, are somewhat consistent with those of a previous study that did not find significant response slowing for apes as a function of aversive testing conditions, although the procedure has been effective in identifying dysregulated fear (high fear in low threat conditions) in macaques. The utility of this paradigm for testing affect in apes awaits further evaluation.

The most popular American writer the year the Civil War began was not, perhaps, American. A nation on the verge of splitting asunder enthusiastically consumed stories of its national identity being consolidated in Africa in a book by Paul Belloni du Chaillu, a young man of ambiguous origins and spectacular credibility issues. His 1861 bestseller Explorations and Adventures in Equatorial Africa about his pith-helmeted exploits marked him as an intrepid scientist or armchair fantasist or, possibly, both. Regardless, his rise from anonymity to transatlantic sensation in a moment of acute national crisis suggests that something important was created and perceived in the shifting identitarian signs of his person and his work. Du Chaillu was not simply a European adventurer or American journalist or African homesteader, all of which he became, for capital of all sorts moved through him in multinational and continental forms. As a result, Du Chaillu deserves a space of prominence in any configuration of a nineteenth-century transatlantic canon. He also merits attention as the author of the last great antebellum American narrative. The fact that the qualifier “American” in that statement is utterly debatable is entirely, given 1861, the point.

Mountain gorillas (Gorilla beringei beringei) are an endangered primate species, with ~43% of the 1,063 individuals that remain on the planet today residing in Bwindi Impenetrable National Park (BINP) in southwestern Uganda. These primates are at the heart of a growing tourism industry that has incentivized their continued protection, but close proximity between humans and gorillas during such encounters presents well-documented risks for disease transmission. The Uganda Wildlife Authority (UWA) has developed rules to help protect the health of the gorillas, limiting each habituated gorilla group to a single 60 min visit each day by a group of no more than 8 tourists, and emphasizing that humans maintain a >7 m distance from gorillas at all times. A number of studies have documented that not all tour groups respect these rules. This project assesses rule-adherence during gorilla tourism encounters at BINP using both observational and survey-based data collected during the tourism high season between May and August, 2014. Observational data from 53 treks reveal that groups of 1–11 tourists engaged in gorilla viewing encounters between 46 and 98 min in duration. Although 96% of pre-trek briefings conducted by park rangers emphasized the need to maintain >7 m human-gorilla spacing, the 7 m distance rule was violated in over 98% (52 out of 53) of the tours examined in this study. Observational data were collected at 2 min intervals during gorilla-viewing encounters, documenting the nearest distance between any tourist and a gorilla (n = 1,604), of which 1,094 observations (68.2%) took place at a distance less than or equal to 7 m. Importantly, the 7 m rule was violated in visits to all of the gorilla groups habituated during the time of the study. In 224 observations (~14%, per 1,604 total), human-gorilla spacing was 3 m or less. Survey data (n = 243) revealed promising opportunities to improve tourist understanding of and adherence to park rules, with 73.6% of respondents indicating that they would be willing to utilize a precautionary measure of wearing a face-mask during encounters to protect gorilla health.

Decisions about which foods to use during training and enrichment for captive animals may be based on invalid assumptions about individuals’ preferences. It is important to assess the stability of food preferences given that one-time preferences are often used to inform which items are offered over a longer period of time. Presenting preference assessments using images of food items allows control over factors such as size, scent, and inadvertent cueing but requires validation. We presented three male gorillas with choices between randomly selected pairs of actual food items from their morning meal using PVC feeders. We also presented the gorillas with two-alternative forced-choice tests between images of these foods on a touchscreen computer. Ranked preferences were correlated across method and seasons. Furthermore, gorillas selected images of preferred over less preferred foods in a validation task on the touchscreen. However, selections of some food items changed within sessions, suggesting that preference may be relative to other contextual factors. Researchers should assess how choices affect subsequent preferences to understand whether animals demonstrate absolute preferences for particular food items, or prefer variety.

Monitoring changes in cortisol levels is a widespread tool for measuring individuals’ stress responses. However, an acute increase in cortisol levels does not necessarily denote an individual in distress, as increases in cortisol can be elicited by all factors that signal the need to mobilize energy. Nor are low levels of cortisol indicative for a relaxed, healthy individual. Therefore, a more fine-grained description of cortisol patterns is warranted in order to distinguish between cortisol fluctuations associated with different stress response qualities. In most species, cortisol shows a distinct diurnal pattern. Using a reaction norm approach, cortisol levels across the day can be described by the two regression coefficients: the intercept and the slope of the curve. We measured immunoreactive salivary cortisol in three zoo-housed ape species under three conditions (routine days, enrichment days, and after the move to a new house). We examined salivary cortisol intercepts (SCI) and salivary cortisol slopes (SCS) of the diurnal curves. SCI and SCS were independent from each other. SCI was highest on enrichment days and lowest on routine days. SCS was steep on routine days and blunted after the move. Only SCI was species-specific. Our study provides evidence that combining SCI and SCS measures allows us to differentiate between types of stress responses, thereby constituting a useful tool for welfare assessment.

Cognitive research in zoos is often limited by an inability to consistently train and reinforce subjects. This feasibility study aims to address this problem by examining visual processing of faces by Western lowland gorillas (Gorilla gorilla) at a zoo in order to identify gaze patterns without any training or reward. A Tobii Pro X2-30 eye-tracker mounted on a TV monitor was used. Participation by the gorillas was voluntary in that no training or reinforcement was provided. Two gorillas (a four-year-old female and a one-year-old male) attended sufficiently to the screen to collect gaze data. In order to further validate the calibration procedure used with gorillas, 61 human participants were tested using the same equipment and stimuli. Images were unfamiliar gorilla females with neutral expressions. Areas of interest were identified for the eye region, lower face (mouth and nasal areas), and overall face, and the patterns of fixation to each region were examined. Gorillas tended to focus less on the eyes than did humans. The current results highlight the feasibility of this kind of data collection without the use of training or reinforcement.

Abstract Background Simian immunodeficiency viruses (SIVs) of chimpanzees and gorillas from Central Africa crossed the species barrier at least four times giving rise to human immunodeficiency virus type 1 (HIV-1) groups M, N, O and P. The paradigm of non-pathogenic lentiviral infections has been challenged by observations of naturally infected chimpanzees with SIVcpz associated with a negative impact on their life span and reproduction, CD4+ T-lymphocyte loss and lymphoid tissue destruction. With the advent and dissemination of new generation sequencing technologies, novel promising markers of immune deficiency have been explored in human and nonhuman primate species, showing changes in the microbiome (dysbiosis) that might be associated with pathogenic conditions. The aim of the present study was to identify and compare enteric viromes of SIVgor-infected and uninfected gorillas using noninvasive sampling and ultradeep sequencing, and to assess the association of virome composition with potential SIVgor pathogenesis in their natural hosts. Results We analyzed both RNA and DNA virus libraries of 23 fecal samples from 11 SIVgor-infected (two samples from one animal) and 11 uninfected western lowland gorillas from Campo-Ma’an National Park (CP), in southwestern Cameroon. Three bacteriophage families (Siphoviridae, Myoviridae and Podoviridae) represented 67.5 and 68% of the total annotated reads in SIVgor-infected and uninfected individuals, respectively. Conversely, mammalian viral families, such as Herpesviridae and Reoviridae, previously associated with gut- and several mammalian diseases were significantly more abundant (p

Background: Individuals experiencing negative affect have shown response slowing, a longer latency to respond in relation to baseline, when presented with aversive stimuli. We assessed response slowing in three male gorillas housed in a bachelor group as a function of daytime and nighttime housing arrangements. Methods: In both experiments, three gorillas were rewarded for touching a single image (baseline, non-threatening gorilla or threatening gorilla) on a touchscreen. In Experiment One, they completed 48 50-trial sessions across combinations of three nested daytime and three nighttime conditions. In Experiment Two, they completed eight 50-trial sessions with novel stimuli across two daytime conditions, which were nested within two nighttime conditions. Housing conditions represented different amounts of space and degree of choice. We predicted that the gorillas would show response slowing to threatening stimuli when space and choice were restricted. Results: We did not observe response slowing in Experiment One, although daytime and nighttime conditions interacted to predict response latencies. The gorillas responded more slowly when they had access to indoors and outdoors overnight compared to when they were in their stalls or together in an indoor habitat, but only if they had been given access to both indoors and outdoors or locked in the indoor habitat the day before. In Experiment Two, the gorillas did show response slowing to threatening stimuli, but this pattern did not interact with housing conditions. Our results, although limited by a small sample, are somewhat consistent with those of a previous study that did not find significant response slowing for apes as a function of aversive testing conditions, although the procedure has been effective in identifying dysregulated fear (high fear in low threat conditions) in macaques. The utility of this paradigm for testing affect in apes awaits further evaluation. [ABSTRACT FROM AUTHOR]

Human adenoviruses have many attractive features for gene therapy applications. However, the high prevalence of preexisting immunity against these viruses in general populations worldwide has greatly limited their clinical utility. In addition, the most commonly used human adenovirus, human adenovirus subgroup C serotype 5 (HAd5), when systemically administered, triggers systemic inflammation and toxicity, with the liver being the most severely affected organ. Here, we evaluated the utility and safety of a new low-seroprevalence gorilla adenovirus (GAd; GC46) as a gene transfer vector in mice. Biodistribution studies revealed that systemically administered GAd had a selective and robust lung endothelial cell (EC) tropism with minimal vector expression throughout many other organs and tissues. Administration of a high dose of GAd accomplished extensive transgene expression in the lung yet elicited no detectable inflammatory histopathology in this organ. Furthermore, GAd, unlike HAd5, did not exhibit hepatotropism or induce liver inflammatory toxicity in mice, demonstrating the exceptional safety profile of the vector vis-à-vis systemic utility. We further demonstrated that the GAd capsid fiber shared the flexibility of the HAd5 equivalent for permitting genetic modification; GAd with the pan- EC-targeting ligand myeloid cell-binding peptide (MBP) incorporated in the capsid displayed a reduced lung tropism and efficiently retargeted gene expression to vascular beds in other organs. [ABSTRACT FROM AUTHOR]

Background and objectives The study reported here focused on the aetiology of spondylolysis, a vertebral pathology usually caused by a fatigue fracture. The goal was to test the Overshoot Hypothesis, which proposes that people develop spondylolysis because their vertebral shape is at the highly derived end of the range of variation within Homo sapiens. Methodology We recorded 3D data on the final lumbar vertebrae of H. sapiens and three great ape species, and performed three analyses. First, we compared H. sapiens vertebrae with and without spondylolysis. Second, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae. Lastly, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae and to vertebrae of H. sapiens with Schmorl's nodes, which previous studies have shown tend to be located at the ancestral end of the range of H. sapiens shape variation. Results We found that H. sapiens vertebrae with spondylolysis are significantly different in shape from healthy H. sapiens vertebrae. We also found that H. sapiens vertebrae with spondylolysis are more distant from great ape vertebrae than are healthy H. sapiens vertebrae. Lastly, we found that H. sapiens vertebrae with spondylolysis are at the opposite end of the range of shape variation than vertebrae with Schmorl's nodes. Conclusions Our findings indicate that H. sapiens vertebrae with spondylolysis tend to exhibit highly derived traits and therefore support the Overshoot Hypothesis. Spondylolysis, it appears, is linked to our lineage's evolutionary history, especially its shift from quadrupedalism to bipedalism. Lay summary: Spondylolysis is a relatively common vertebral pathology usually caused by a fatigue fracture. There is reason to think that it might be connected with our lineage's evolutionary shift from walking on all fours to walking on two legs. We tested this idea by comparing human vertebrae with and without spondylolysis to the vertebrae of great apes. Our results support the hypothesis. They suggest that people who experience spondylolysis have vertebrae with what are effectively exaggerated adaptations for bipedalism. [ABSTRACT FROM AUTHOR]

Triadic interactions are an important developmental milestone for young human infants, ultimately enabling them to acquire language. When an infant and a caregiver share attention regarding an object, the label given to the object becomes linked with the object, hence referential communication is established through which infants learn to associate words with meanings. In fact, triadic interactions are considered so crucial to human language development that their phylogenetic origins have become the focus of investigation to study the evolutionary history of language. In this paper, we report a communicative instance of a captive zoo gorilla apparently trying to engage zoo visitors in a joint task of retrieving food. The gorilla seemed to initiate a series of combined triadic interactions with different tools used as pointing devices while attempting to recruit a human for help. Even though it is a single observation event, we argue that the gorilla possessed relevant knowledge about the various purposes for which a specific tool can be used and utilized sophisticated communicative means in her interaction with humans.

In nonhumans, ‘optimism’ is often defined as responding to an ambiguous item in the same manner as to items previously associated with reward (or lack of punishment), and “pessimism” is defined as responding to an ambiguous item in the same manner as to items previously associated with a lack of reward (or with punishment). We measured the degree of “optimism” and “pessimism” in three captive male western lowland gorillas (Gorilla gorilla gorilla) during four consecutive two-week periods in which the amount of available forage material (mulberry, Moraceae or alfalfa, Medicago sativa) was manipulated. We assessed cognitive bias using an ambiguous cue paradigm for the first time. Pairs of two-dimensional shapes were presented on a touch-screen computer in a forced choice task in which one shape was always reinforced (P), one was never reinforced (N), and one was reinforced half the time, making it ambiguous (A). The gorillas were presented with an equivalent number of PA and NA pairs prior to testing, which also included probe trials of ambiguous items paired with novel items. During the limited forage phase, the gorillas, as a group, selected the ambiguous stimulus (indicating optimism) at a level greater than chance; tests for all other phases were non-significant. The gorillas displayed individual differences in learning PA and NA trials and in their choice of ambiguous items on test trials. Idiosyncratic preferences for particular stimuli suggest that the ambiguous cue paradigm may not be ideal for assessing cognitive bias in nonhumans.

The tropical forests of Western Equatorial Africa are home to extraordinary biodiversity, including sympatric chimpanzees (Pan troglodytes troglodytes) and western lowland gorillas (Gorilla gorilla gorilla). The region is also comprised of significant stands of Intact Forest Landscapes (IFL) that are in rapid decline. As part of a regional monitoring effort, we partnered with local government officials, conservation NGOs, and the timber company working in the region to assess ape abundances in relation to habitat characteristics and anthropogenic disturbances and compare IFL and non-IFL areas in the Sangha Trinational landscape, Republic of Congo. We found that chimpanzees and gorillas occur at high densities in IFL, as well as non-IFL. To better understand how selective logging changes floristic factors, we compared herb and tree densities from botanical surveys conducted in IFL and non-IFL. IFL had higher tree stem densities and less terrestrial herbs than logged habitats. However, few ape resources were logged in this extraction cycle and areas with tree stems removed subsequently had higher abundances of terrestrial herbs preferred by apes, which may contribute to the elevated ape abundance estimates. Floristic differences in logged forest were identified to coincide with differences in ape resource use. The chimpanzee tree nesting niche was reduced in non-IFL as night nests were constructed significantly closer to the ground than in IFL. Whereas, gorilla nest height locations did not differ significantly between IFL and non-IFL. To identify other potential anthropogenic impacts, we assessed direct and indirect impacts of road expansion and illegal hunting on wildlife in these remote areas. Increased access to IFL that facilitates illegal hunting raises concern for protecting wildlife across Western Equatorial Africa. We urge that the results of biodiversity assessments and strategic aspects of long-term protection should be taken into account when identifying conservation set-asides and maintaining diverse states of modified forests. Finally, the results of our monitoring efforts are provided as evidence of the value of long-term collaborations among local stakeholders, government officials, conservation agencies, and industrial partners to improve the implementation of certification standards and biodiversity conservation initiatives.

In contrast to reports of wild primates, studies of captive primates’ flexibility often reveal conservatism: individuals are unable to switch to new and more efficient strategies when task demands change. We propose that such conservatism might be a result of task design and hypothesize that conservatism might be linked to primates’ lack of causal understanding in relation to experimental apparatuses. We investigated if chimpanzees (Pan troglodytes) and western lowland gorillas (Gorilla gorilla gorilla) would show greater flexibility when presented with a causally-clear task. We presented six chimpanzees and seven gorillas with a clear tube from which they had to remove straws to release a reward. To first evaluate the apes’ causal understanding, we recorded the efficiency with which the apes solved the task (i.e., whether they only removed straws below the reward, ignoring redundant ones above it). To further explore how they solved the task, we also recorded the order in which they removed the straws, which allowed us to determine if habitual action sequences emerged. All apes spontaneously solved the task in their first trial and across repeated trials the majority of their solutions were efficient (median = 90.9%), demonstrating their understanding of the puzzle. There was individual variation in the consistency of straw removal patterns exhibited by the apes, but no ape developed an exclusive habit in the order with which they removed the straws, further indicating their causal understanding of the task. Next, we presented the apes with a new configuration of the same task that required the apes to remove fewer straws to obtain the reward. All apes switched to a more efficient straw removal sequence even though their previously-successful, but now less-efficient, solution remained available. We theorize that because the apes understood the causality of the task, they did not form habits and were not conservative.