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We examine the effects of foreign currency borrowings (FCBs) and domestic market constraints on the performance of the export of the micro, small and medium enterprises (MSMEs) during the period 1988–2019. Our results show that access to the FCBs improved the performance of the MSME exports, indicating the importance of credit accessibility. MSMEs effectively utilise the grants when accompanied by credit facilities such as FCBs. We find that the high cost of debt and lack of financial development adversely affect the exports, as MSMEs are unable to borrow. The rupee depreciation alone does not help the MSMEs reap such depreciation benefits due to the lack of domestic credit. The recent policy stance of emphasis on MSMEs is expected to improve export performance. This study calls for the specialised window for the MSMEs to meet low cost and easy credit. The findings suggest stepping up grants to the MSMEs to improve the export performance. JEL Codes: F14, F34, F2, F31

The aims of this study were to determine the current prevalence of regurgitation and reingestion (R/R) and gain an insight on the occurrence of coprophagy in the Association of Zoos & Aquariums (AZA) gorilla (Gorilla gorilla gorilla) population. To do this, an online survey was sent to all AZA accredited gorilla institutions in 2018. This survey collected information on the severity of R/R at the individual level and the occurrence of coprophagy at the zoo level. Previous research suggests more than half of zoo-housed gorillas in the North American population engaged in R/R and coprophagy to some extent. The current study had a 100% response and completion rate; data were collected on all 296 noninfant gorillas in the population. Responses indicated that 60% of the AZA gorilla population engages in R/R to some degree and 24% of the population are observed exhibiting coprophagy on a weekly basis. With this preliminary information on coprophagy, and the realization that the Zoo community has been unsuccessful at eliminating R/R over the past 30 years, the next steps should be aimed at empirically assessing the potential drivers of these behaviors. Continuing efforts to further understand and eliminate R/R and coprophagy in zoo-housed primates is important not only because these behaviors are unsightly to visitors, but more importantly, R/R and coprophagy may signal deficiencies in current practices surrounding animal care.

The effect visitors may have on the welfare of professionally managed animals is vital to consider. The present study utilized an experimental approach to examine how 360° visitor viewing access (i.e., viewing from all sides of the habitat) impacts the behavior and physiology of Western lowland gorillas (Gorilla gorilla gorilla, N = 7). Data collection included behavioral observations and obtaining fecal samples to examine physiological indicators of welfare. The study included a baseline period observing the gorillas’ behavior and physiology during the typical 360° visitor viewing access and a treatment period examining the same indicators but reducing viewing access by approximately 70%. Behavioral states, behavioral events, and hormone data were compared across conditions using Wilcoxon signed-rank tests. Restricted viewing did not impact social or solitary grooming (as a state behavior), social or solitary play, foraging, stereotypies, locomotion, inactivity, or behavioral diversity. However, restricted viewing significantly reduced solitary grooming events, fecal glucocorticoid metabolites, and the ratio of glucocorticoid metabolites to dehydroepiandrosterone metabolites. These results suggest that 360° visitor viewing access may have an impact on the welfare of gorillas. However, further research is necessary to thoroughly understand the influence of allowing 360° visitor viewing on behavior and its possible interaction with variables of the zoo environment.

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. Ecology, Not Host Phylogeny, Shapes the Oral Microbiome in Closely Related Species

Varicose projection astrocytes (VP-As) are found in the cerebral cortex and have been described to be specific to humans and chimpanzees. To further examine the phylogenetic distribution of this cell type, we analyzed cortical tissue from several primates ranging from primitive primates to primates evolutionary closer to human such as apes. We specifically analyzed tissue from four strepsirrhine species, one tarsier, six species of platyrrhine monkeys, ten species of cercopithecoid monkeys, two hylobatid ape species, four to six cases each of chimpanzee, bonobo, gorilla, and orangutan, and thirteen human. We found that VP-As were present only in human and other apes (hominoids) and were absent in all other species. We showed that VP-As are localized to layer VI and the superficial white matter of the cortex. The presence of VP-As co-occured with interlaminar astrocytes that also had varicosities in their processes. Due to their location, their long tangential processes, and their irregular presence within species, we propose that VP-As are astrocytes that develop varicosities under specific conditions and that are not a distinct astrocyte type.

In humans, inflammatory markers predict health risks. As great apes experience many similar conditions, measuring inflammation may provide valuable health information. We examined four serum inflammatory markers in zoo-housed gorillas (n = 48): albumin, CRP, IL-6, and TNF-α. We first analyzed age- and sex-associated patterns, then used multimodel inference to evaluate models with age, sex, and inflammatory markers as predictors of all-cause morbidity, cardiac disease, and mortality. Older gorillas had lower albumin and higher IL-6, and males had higher albumin, lower CRP, and lower TNF-α. All-cause morbidity was best predicted by age, sex, and TNF-α, but the second model containing only age and sex was equivalent. Cardiac disease was best predicted by TNF-α alongside age and sex, with lower levels associated with increased risk. When outliers were removed, the model with TNF-α was second to the model containing only age and sex. Finally, mortality risk was best predicted by the model with only age and sex. Other models containing individual inflammatory markers were within top model sets for each health outcome. Our results indicate that age and sex are robust for predicting all-cause morbidity and mortality risk in gorillas; while models which include individual inflammatory markers also predict risk, they may not improve predictions over age and sex alone. However, given the prevalence of cardiac disease in great apes, these results suggest that TNF-α warrants further investigation. With their potential to provide valuable health information, data on inflammatory markers may contribute to the care and management of gorillas in human care.

Highly differentiated and affiliative social relationships are observed in a variety of mammals, including primates, cetaceans, and social carnivores. Although there has been a transformation in our understanding of the form and function of social bonds in the past two decades, the role of early life social experiences in the development of bonds remains less clear. Few studies have examined whether social relationships during infancy and juvenility (aside from those between mothers and offspring) persist into adulthood. In this study, we used longitudinal data on wild chimpanzees (Pan troglodytes schweinfurthii) at Gombe National Park, Tanzania, to investigate the effects of party-level association during infancy and juvenility (hereafter immaturity) on affiliative relationships among adult males (the philopatric sex). In total, we examined behavioral data from focal follows between 1970 and 2015 (N = 23 adult males). We used maternal associations as proxies for the associations of immature males, and we measured adult male social relationships using party-level associations and grooming activity. We found that immature males that associated with individual adult males at higher rates had stronger relationships with those same adult males later in life. By contrast, rates of association between pairs of immature males did not predict the strength of their dyadic relationships as adults. Overall, these findings emphasize the importance of early socialization in male chimpanzee social development. These results also reinforce studies in mountain gorillas (Gorilla beringei) and bottlenose dolphins (Tursiops sp.), suggesting that the persistence of social relationships that do not involve the mother may be more likely to evolve in long-lived species where young adult males face challenges entering an adult hierarchy composed of stronger and/or more socially experienced competitors.

Metaheuristics play a critical role in solving optimization problems, and most of them have been inspired by the collective intelligence of natural organisms in nature. This paper proposes a new metaheuristic algorithm inspired by gorilla troops' social intelligence in nature, called Artificial Gorilla Troops Optimizer (GTO). In this algorithm, gorillas' collective life is mathematically formulated, and new mechanisms are designed to perform exploration and exploitation. To evaluate the GTO, we apply it to 52 standard benchmark functions and seven engineering problems. Friedman's test and Wilcoxon rank-sum statistical tests statistically compared the proposed method with several existing metaheuristics. The results demonstrate that the GTO performs better than comparative algorithms on most benchmark functions, particularly on high-dimensional problems. The results demonstrate that the GTO can provide superior results compared with other metaheuristics.

The benzimidazole anthelmintic drug albendazole becomes metabolized to chiral albendazole sulfoxide, albendazole sulfone, albendazole 2-aminosulfone, and other metabolites. High-performance liquid chromatography with UV absorbance and fluorescence detection, liquid chromatography with mass spectrometry, and chiral electrokinetic chromatography were used to analyze albendazole metabolites in extracts of western lowland gorilla (Gorilla gorilla gorilla) plasma of patients with alveolar echinococcosis and the data are compared to those obtained with human patient samples and to those reported for other species in the literature. The data revealed that the albendazole sulfoxide to albendazole sulfone concentration ratio in gorilla plasma is significantly smaller compared to that in samples of men, rats, dogs, and cattle. It is, however, similar to what was observed in sheep and goats. The (+)-albendazole sulfoxide to (���)-albendazole sulfoxide enantiomeric ratio in gorilla blood determined by chiral electrokinetic chromatography was found to be >1 which is comparable to what was observed in humans, dogs, sheep, goats, and cattle but different to mice and rats. Furthermore, the electrokinetic chromatography data suggest that small amounts of albendazole 2-aminosulfone may be present in plasma of gorillas and humans. The data gathered with the various separation-based assays illustrate the value of technology featuring different analyte separation and detection principles. This is the first account describing aspects of the albendazole metabolism in gorillas.

(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.

The present study will investigate the role of language-based and vision-based information in the comprehension of words, using a semantic priming experiment. A demonstration of the experiment is available at https://pablobernabeu.github.io/language-vision-semanticpriming/index.html

Ecology, not host phylogeny, shapes the oral microbiome in closely related species Studying the oral microbiome of three gorilla subspecies using a shotgun metagenomic approach on dental calculus. The workflow is adapted from Brealey et al. 2020. ## Pre-processing of reads Script for demultiplexing is not included here. - 2_polyGrem: Removal of PolyG tails - 3_adapterRem: Adapter removal and merging of paired-end reads - 4_barcodeTrim: Barcode trimming - 5_qualityFilt: Quality filtering - 6_deduplicate: Removal of duplicates - 7_phixRem: Removal of sequences mapping to the PhiX genome - 8_humanHostFilt: Removal of sequences mapping to the human and gorilla genome ## Host mtDNA analysis - H1_mtgenomes: Obtaining mt genomes from dental calculus by mapping to a the gorilla mitochondrial genome reference. Script for obtaining mitochondrial sequences using a reference genome were adapted from Samantha Lopez Clinton's work. - H2_haplotype_network: Plot haplotype network using downloaded complete mt genomes and dental calculus genomes > 80% complete. For dental calculus genomes < 80% and > 8% complete, find the most closely related genome from the haplotype network based on ANI values. Haplotype network script plot_hapnets.r was adapted from Zach Nolen's work. (not used in final report) - H3_diagnostic_sites: Identifying and using mitochondrial diagnostic sites to verify species and subspecies assignments. Python and R scripts (DistanceToReferences.py, FindDiagnosticSites_edited.py, plot_readCoverage.r) were adapted from Axel Jensen's work. ## Taxonomic classification and analysis - T1_kraken2: Taxonomic classification using Kraken2. - T2_bracken: Re-estimation of taxa abundances using Bracken - T3_community-level: Rscripts for the analysis of the taxonomic classification output (decontamination, abundancefiltering, PERMANOVA, identification of differentially abundant taxa, etc.) ## Read-level decontamination and MapDamage - RD3: The scripts in this directory are run as part of the taxonomic-level analysis scripts in T3_community-level, in order to identify contaminants based on damage patterns. Takes list of taxa that are found in both oral and contaminant lists (produced by T3_community-level/6a_reference_based_decontam.R) and are represented by a sufficient number of reads, downloads one genome per taxon and then runs mapDamage. The output is then processed with T3_community-level/6b_reference_based_decontam.R - RD1: First step of read-level decontamination of the FastQ files. Removes reads that were assigned to identified contaminants by Kraken2. - RD2: Second step of read-level decontamination of the FastQ files. Removed contaminant reads by mapping to a concatenated file of all contaminant genomes. ## Functional profiling and analysis - F1_HUMAnN2: Functional profiling using HUMAnN2 - F2_functional_stats: Rscripts for the analysis of the functional profiling output (identify subspecies associated biological processes, quantify contributions of different taxa to biological processes, etc.) ## Metagenomes-assembled genomes (MAGs) - M1_metawrap: assembly, binning, refinement, taxonomic classification, and phylogenies of MAGs - M2_isolation-sources: Isolation source information from multiple databases, categorization and visualization of isolation sources for each MAG - M3_trees: scripts for producing core-gene trees for select oral taxa, using Phylophlan. - M4_pangenome: scripts for running pangenomic analyses ## Analyses of dietary components - D1_reads4Diet: Preprocessing for diet profiling, uses Kraken2 output to extract the reads that have been classified as bacterial, viral or archeal - D2_kraken2_full_db: Run of kraken2 on the NCBI full-nt database, with genus and species level assignments retained. - D3_diet_stats: Vary analyses with kraken output of dietary components. Constructing of reference database of dietary components. Preprocessing and filtering of abundance table for dietary taxa. ANCOM and PERMANOVAs on the filtered dataset of dietary taxa. - D4_diet_damage: extracts reads used to assign a given dietary taxon, maps these reads to a reference genome, and runs mapDamage to get the misincorporation rates. ## Misc. Analyses, plots, tables, other stats - frag_length_vs_samp_age: script for plotting the relationship between the average fragment length for each sample and the sample age - microbial_vs_diet_MRM: script for plotting the relationship between microbial and dietary distances - plots: scripts for producing most figures presented in the report and the supplement - tables_and_stats: script producing most information provided in supplementary tables

We will conduct a masked priming experiment using the online experiment platform Gorilla (Gorilla.ms). Masked priming was first introduced by Forster and Davis (1984), and involves a target word (e.g., TEACH) being preceded by either a related/identity prime (e.g., teach or school) or an unrelated word (e.g., carpet) presented for less than 40ms. The primes are forward masked by being preceded by strings of symbols (e.g., #####), and usually backwards masked by the target. It is now a well-established paradigm in psycholinguistics that has been used extensively to investigate morphological processing (see Rastle & Davis, 2008). The masked priming paradigm relies on very high accuracy for stimulus presentation latency. We are not aware of any attempt to use an entirely online experiment running platform to conduct a masked priming experiment. This project therefore seeks to determine whether online stimulus presentation timing accuracy is sufficiently reliable to replicate well established masked priming effects. Additionally, this masked priming experiment will be conducted in Tagalog (Austronesian, Philippines), rather than English or another commonly studied language, as part of a much-needed push to diversify psycholinguistics research, and normalise the use of a broader range of languages for methods-focused research.

Projekt Zaliczeniowy

Studying the effect of focus-oriented tasks of varied difficulty on the tendency to miss distinctive changes within the field of attention.

Small-scale comparisons help us to understand how habitat features and food availability impact primate abundance. This is particularly useful at sites without human impacts, as it allows for the investigation of the natural factors influencing nesting patterns and great ape abundance. We provide a small-scale study of sympatric great ape nests in an unlogged old-growth forest without poaching activities. We conducted a line transect survey (52 km total effort) around Mbeli Bai, a forest clearing in Nouabale–Ndoki National Park, Congo, applying on-site nest decay rates and assigning nest builder using logistic regression. We found a high occurrence of monodominant Gilbertiodendron dewevrei at Mbeli Bai (34%) that correlates with low great ape densities at Mbeli Bai. Chimpanzees (Pan troglodytes troglodytes) showed a preference for nesting in trees in closed canopy monodominant forest. We found a low percentage of gorilla (Gorilla gorilla gorilla) nests in mixed species forest (35%) and a higher percentage in trees (64%) compared to other study sites. However, generalized additive models found higher gorilla nest encounter rates in mixed species forest with dense understory than in monodominant forest and open understory. We found no indication of higher gorilla densities close to Mbeli Bai than elsewhere, and line transect estimates were lower than the number of gorillas revealed from direct observations. There were substantial differences between our findings and those for nearby sites, demonstrating the utility of small-scale comparisons to further understand the factors determining chimpanzee and gorilla densities within and between sites and the limitations of nest surveys.

This article examines the work of mid-century French filmmaker Jacques Tati. Tati suggested that his films allow more visual freedom to audiences and that audiences discover new material upon multiple viewings of his films. We review the scholarship on Tati, especially in relation to critic André Bazin’s theories of realism, and then propose another model for understanding Tati’s films: the psychological concept of inattentional blindness. The article then discusses our experiment using eye tracking technology to study how subjects watch Tati’s films versus other types of cinema and also how they re-watch films. Finally, we applied several statistical and mathematical tests to the eye tracking data to understand key differences between Tati’s films and other filmmaking practices.

A descoberta científica do gorila ensejou nova polêmica em torno da classificação dos primatas. Como classificá-lo entre os hominídeos? A curiosidade científica e popular deu azo a fantasias em torno do maior primata. Qual seria o seu comportamento sexual? No imaginário colonial, o gorila esteve por muito tempo entre o humano e o bestial. Para alguns, o gorila era o elo perdido da evolução humana, para outros uma raça degenerada. Essa ambiguidade marca a produção de sentidos, notadamente aquela de viés racista. Discute-se também sobre eventuais permanências e desdobramentos dessas fantasias em meados do século XX. The scientific discovery of the gorilla brought new altercations regarding the classification of primates. How to allot the gorilla among the hominids? Popular and scientific curiosity incited fantasies with the largest primate. What would be its sexual behavior? In the colonial imaginary, the gorilla has long been between the human and the bestial. Some claimed the gorilla was the missing link of human evolution; others thought it was a degenerate race. Such ambiguity characterizes the production of meanings about the gorilla, notably that with racist tones. The paper also addresses the possible permanence and unfolding of such fantasies in the mid-twentieth century.

A 30-year-old free-ranging female mountain gorilla (Gorilla beringei beringei) developed a perioral mass that was surgically debulked and diagnosed as malignant melanoma. After tumor recurrence, a canine melanoma vaccine was administered. However, the gorilla died shortly thereafter, and metastases to lymph nodes, lung, liver, and kidney were found post-mortem.

Acoustic signals that reliably indicate body size, which usually determines competitive ability, are of particular interest for understanding how animals assess rivals and choose mates. Whereas body size tends to be negatively associated with formant dispersion in animal vocalizations, non-vocal signals have received little attention. Among the most emblematic sounds in the animal kingdom is the chest beat of gorillas, a non-vocal signal that is thought to be important in intra and inter-sexual competition, yet it is unclear whether it reliably indicates body size. We examined the relationship among body size (back breadth), peak frequency, and three temporal characteristics of the chest beat: duration, number of beats and beat rate from sound recordings of wild adult male mountain gorillas. Using linear mixed models, we found that larger males had significantly lower peak frequencies than smaller ones, but we found no consistent relationship between body size and the temporal characteristics measured. Taken together with earlier findings of positive correlations among male body size, dominance rank and reproductive success, we conclude that the gorilla chest beat is an honest signal of competitive ability. These results emphasize the potential of non-vocal signals to convey important information in mammal communication.

LINE-1-mediated retrotransposition of protein-coding mRNAs is an active process in modern humans for both germline and somatic genomes. Prior works that surveyed human data mostly relied on detecting discordant mappings of paired-end short reads, or exon junctions contained in short reads. Moreover, there have been few genome-wide comparisons between gene retrocopies in great apes and humans. In this study, we introduced a more sensitive and accurate method to identify processed pseudogenes. Our method utilizes long-read assemblies, and more importantly, is able to provide full-length retrocopy sequences as well as flanking regions which are missed by short-read based methods. From 22 human individuals, we pinpointed 40 processed pseudogenes that are not present in the human reference genome GRCh38 and identified 17 pseudogenes that are in GRCh38 but absent from some input individuals. This represents a significantly higher discovery rate than previous reports (39 pseudogenes not in the reference genome out of 939 individuals). We also provided an overview of lineage-specific retrocopies in chimpanzee, gorilla, and orangutan genomes.

Accurate measures of animal population densities are essential to evaluate conservation status and implement action plans to ensure species survival. Gorilla numbers were assessed using the recce survey method within Moukalaba-Doudou National Park (MDNP) in Gabon using fresh nest counts of up to 1 week old. We walked 3,592 km within a 23.01-km2 study site totalling a sampling effort of 297 days. Encounter rate was 0.12 fresh nests per kilometre, and gorilla density estimates generated by home range sizes (by minimal convex polygon) ranged between 1.14 and 1.48 gorillas/km2. Gorillas preferred mixed forest for nesting over other habitats (Cheason index value 1.31). Results showed that gorilla density values within the study area concurred with previous studies that used line transect methodologies. We conclude that the choice of sampling design is dependent on environmental conditions characterised by each habitat type and target species.

Humans use tools with specific functions to solve tasks more efficiently. However, functional specialization often comes at a cost: It can hinder the production of actions that are not usually performed with those tools, thus resulting in a fixation effect (functional fixedness). Little is known about whether our closest living relatives, the nonhuman great apes, are vulnerable to this detrimental effect of experience. We examined whether great apes from 4 species (N = 35) would become fixated on the familiar action with an object. More precisely, some subjects experienced a novel food item (grissini), either whole or broken into pieces, whereas others did not. Then, subjects faced a task that required them to use the food item to rake in an out-of-reach food reward. Results indicated that all 4 species could use a food item as a tool. Apes were more likely to do so in the first trial when they had not experienced the tool as food before, even though they tasted the food before using it as a tool. Orangutans and bonobos used the food item more often as a tool than chimpanzees. A preference test ruled out that performance was dependent on individual or species food preferences. Our results suggest that apes might have represented one object in two different ways (i.e., as "food" and as "tool") and then became fixated on one of these two representations. However, it is unclear whether the fixation occurred because of the item's prior function or its identity. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Novels about great apes and humans continue to be consistently popular with the reading public, sometimes reaching best-seller status. Media reviews of these books rarely comment on their primatological roots, nor do primatological journals review them. In a non-quantitative, pilot study, I scrutinize six prominent novels, in terms of three questions: How do the novels make use of primatology? What aspects of primatology do they use? How accurate is their use of primatology? Such novels overwhelmingly concentrate on language, with intelligence and sexuality lagging far behind; other topics, such as culture or technology, receive little or no attention. Apes in nature are rarely mentioned. Inaccuracies abound, even at the most basic level of primatological knowledge that easily could be remedied. Both authors and primatologists would benefit from more informative interaction before publication.

OBJECTIVES Weaning is a key life history milestone for mammals that represents both the end of nutritional investment from the perspective of mothers and the start of complete nutritional independence for the infants. The age at weaning may vary depending on ecological, social, and demographic factors experienced by the mother and infant. Bwindi mountain gorillas live in different environmental conditions and have longer interbirth intervals than their counterparts in the Virunga Volcanoes, yet other life history characteristics of this population remain less well known. We use long-term data from Bwindi Impenetrable National Park, Uganda to examine factors related to weaning age. MATERIALS AND METHODS We analyzed data on infants born in four mountain gorilla groups in Bwindi to quantify their age of weaning (defined as last nipple contact) and to test if the sex of offspring, parity, and dominance rank of mother influences age of weaning. We also compared the age at weaning and time to conception after resumption of mating in Bwindi and Virunga gorillas. RESULTS Bwindi gorillas were weaned at an average age of 57.5 months. No difference was found between age of weaning for primiparous and multiparous mothers, nor did maternal dominance rank influence age of weaning, but sons were weaned at a later age than daughters. The majority of Bwindi mothers were still suckling when they resumed mating and mothers generally conceived before they weaned their previous offspring. The age of weaning was significantly later in Bwindi than in Virunga gorillas. After mothers resumed mating, the time to conceiving the next offspring was not significantly longer for Bwindi females than Virungas females (6 vs. 4 months). DISCUSSION Later weaning age for sons than daughters is similar to findings of other studies of great apes. Bwindi mountain gorillas are weaned at approximately the same age as western gorillas and chimpanzees, which is more than a year later than Virunga mountain gorillas. The results of this study suggest that variation in ecological conditions of populations living in close geographic proximity can result in variation in life history patterns, which has implications for understanding the evolution of the unique life history patterns of humans.

Timing of craniofacial suture fusion is important for the determination of demographics and primate ontogeny. There has been much work concerning the timing of fusion of calvarial sutures over the last century, but little comprehensive work focusing on facial sutures. Here we assess the relationships of facial suture fusion across ontogeny among select catarrhines. Fusion timing patterns for 5 facial sutures were examined in 1,599 crania of Homo, Pan, Gorilla, Pongo, Hylobatidae, Papio, and Macaca. Calvarial volume (early ontogeny) and dental eruption (late ontogeny) were used as indicators of stage of development. General linear models, test for homogeneity of slopes, and ANOVA were used to determine differences in timing of fusion by taxon. For calvarial volume, taxonomic groups segregated by regression slopes, with models for Homo indicating sutural fusion throughout ontogeny, Pongo, Macaca, and Papio representing earlier and more complete suture fusion, and Pan, Gorilla, and Hylobatidae indicating very early facial suture fusion. Similar patterns are observed when dental eruption is used for developmental staging. Only Gorilla and Hylobatidae are observed to, generally, fuse all facial suture sites in adulthood. Finally, Homo appears to be unique in its delay and patency of sutures into late ontogeny. The taxonomic patterns of facial suture closure identified in this study likely reflect important evolutionary shifts in facial growth and development in catarrhines.

Although trichromatic colour vision has been extensively studied as it grants significant advantages for Old World primates, it is unknown which selective pressures were behind the trait’s evolution. The leading hypothesis would be that colour vision arose as a foraging adaptation because it allowed individuals to spot food more efficiently. To test this, we exposed 3 chimpanzees (Pan troglodytes), 5 gorillas (Gorilla gorilla) and 3 mandrills (Mandrillus sphinx) to colour cardboard plates to assess whether colours related to diet were the most preferred. The experimental setting was divided into two phases. During the first, animals were provided with colour cardboard plates of only 1 colour per data collection session. The order of colour presentation was randomly determined: white, black, yellow, green and red. In phase 2, primates were simultaneously provided with cardboard plates of all colours. Behavioural interactions with plates were measured using a one-zero group focal sampling (10-s sampling intervals and 20-min observation periods). Results showed that when animals were exposed to only 1 colour at a time, they exhibited different colour preferences depending on the species considered. Chimpanzees preferred red and yellow, the colours linked to fruits, while gorillas selected red and white. Mandrills exhibited fewer differences between colour preferences, with red being the most selected. Furthermore, when all colours were simultaneously provided, individuals chose colours related to diet over black and white. Although there were clear individual differences, our results support that trichromatic colour vision is an advantage in detecting and selecting red items. In the wild, it could be important in the detection of reddish fruits and leaves.

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.

There was a time, not long ago, when communities around Uganda’s Bwindi Impenetrable National Park and the Mgahinga Gorilla National Park were the mountain gorillas’ worst enemies. When the gorillas crossed their gardens, the inhabitants living close to these dense green rainforests would sound an alarm to confront the animals, who were viewed as a menace. This almost certainly resulted in the deaths of many endangered mountain gorillas.

Objectives Many primates change their locomotor behavior as they mature from infancy to adulthood. Here we investigate how long bone cross‐sectional geometry in Pan, Gorilla, Pongo, Hylobatidae, and Macaca varies in shape and form over ontogeny, including whether specific diaphyseal cross sections exhibit signals of periosteal adaptation or canalization. Materials and methods Diaphyseal cross sections were analyzed in an ontogenetic series across infant, juvenile, and adult subgroups. Three‐dimensional laser‐scanned long bone models were sectioned at midshaft (50% of biomechanical length) and distally (20%) along the humerus and femur. Traditional axis ratios acted as indices of cross‐sectional circularity, while geometric morphometric techniques were used to study cross‐sectional allometry and ontogenetic trajectory. Results The humeral midshaft is a strong indicator of posture and locomotor profile in the sample across development, while the mid‐femur appears more reflective of shifts in size. By comparison, the distal diaphyses of both limb elements are more ontogenetically constrained, where periosteal shape is largely static across development relative to size, irrespective of a given taxon's behavior or ecology. Discussion Primate limb shape is not only highly variable between taxa over development, but at discrete humeral and femoral diaphyseal locations. Overall, periosteal shape of the humeral and femoral midshaft cross sections closely reflects ontogenetic transitions in behavior and size, respectively, while distal shape in both bones appears more genetically constrained across intraspecific development, regardless of posture or size. These findings support prior research on tradeoffs between function and safety along the limbs.

Great apes and humans develop many of the same health conditions, including cardiac disease as a leading cause of death. In humans, lipid markers are strong predictors of morbidity and mortality risk. To determine if they similarly predict risk in gorillas, we measured five serum lipid markers and calculated three lipoprotein ratios from zoo-housed western lowland gorillas (aged 6–52 years, n=61, subset with routine immobilizations only: n=47): total cholesterol (TC), triglycerides (TGs), high-density lipoprotein (HDL), low-density lipoprotein (LDL), apolipoprotein A1 (apoA1), TC∕HDL, LDL∕HDL, and TG∕HDL. We examined each in relation to age and sex, then analyzed whether they predicted all-cause morbidity, cardiac disease, and mortality using generalized linear models (GLMs). Older age was significantly associated with higher TG, TC∕HDL, LDL∕HDL, and TG∕HDL, and lower HDL and apoA1. With all ages combined, compared to females, males had significantly lower TG, TC∕HDL, LDL∕HDL, and TG∕HDL, and higher HDL. Using GLMs, age, sex, and lower LDL∕HDL were significant predictors of all-cause morbidity; this is consistent with research demonstrating lower LDL in humans with arthritis, which was the second most prevalent condition in this sample. In contrast to humans, lipid markers were not better predictors of cardiac disease and mortality risk in gorillas, with cardiac disease best predicted by age and sex alone, and mortality risk only by age. Similar results were observed when multimodel inference was used as an alternative analysis strategy, suggesting it can be used in place of or in addition to traditional methods for predicting risk.

OBJECTIVES: Molar crenulation is defined as the accessory pattern of grooves that appears on the occlusal surface of many mammalian molars. Although frequently used in the characterization of species, this trait is often assessed qualitatively, which poses unavoidable subjective biases. The objective of this study is to quantitatively test the variability in the expression of molar crenulation in primates and its association with molar size and diet. METHODS: The variability in the expression of molar crenulation in hominids (human, chimpanzee, gorilla, and orangutan) was assessed with fractal analysis using photographs of first, second and third upper and lower molars. After this, representative values for 29 primate species were used to evaluate the correlation between molar complexity, molar size, and diet using a phylogenetic generalized least squares regression. RESULTS: Results show that there are statistically significant differences in fractal dimensions across hominid species in all molars, with orangutan molars presenting higher values of occlusal complexity. Our results indicate that there is no significant association between molar complexity and molar size or diet. DISCUSSION: Our results show higher levels of occlusal complexity in orangutans, thus supporting previously published observations. Our analyses, however, do not indicate a clear association between molar complexity and molar size or diet, pointing to other factors as the major drivers of complexity. To our knowledge, our study is the first one to use fractal analysis to measure occlusal complexity in primates. Our results show that this approach is a rapid and cost-effective way to measure molar complexity.

Portraits of humans favour the left cheek, with emotion thought to drive this posing asymmetry. In primates the emotion-dominant right hemisphere predominantly controls the left hemiface, rendering the left cheek anatomically more expressive than the right. As perceptions of nonhuman primates vary with genetic relatedness, depictions of nonhuman primates should theoretically be influenced by their phylogenetic proximity to humans. The present study thus examined whether humans depict nonhuman primates showing the left cheek, and whether depictions vary with evolutionary distance. Photographs of nonhuman primates were sourced from Instagram's "Most recent" feed: great apes (#chimpanzee, #bonobo, #gorilla, #orangutan), lesser apes (#gibbon), Old World monkeys (#baboon, #macaque, #proboscismonkey), New World monkeys (#spidermonkey, #marmosetmonkey, #capuchin), and prosimians (#lemur, #slowloris, #tarsier). The first 500 single-subject images for each hashtag (except #slowloris for which 318 images were available) were coded for pose orientation (left, right) and portrait type (head/torso, full body). As anticipated, there was a left cheek bias for great apes but no bias for more distantly related primates. These data thus suggest that depictions of nonhuman primates are implicitly influenced by phylogenetic proximity: the more closely related the primate, the more likely we are to depict them as we do ourselves, showing the left cheek.

In social species, such as many primate species, conspecifics can pose a threat and individuals that are socially vigilant can prevent harassment. Many previous studies have focused on the role of agonistic interactions on social vigilance. In a variety of primate species, individuals are more vigilant for aggressive or dominant group members. In contrast, only few studies have investigated whether affiliative relationships also affect social vigilance. These studies revealed that individuals with an affiliative relationship showed lower levels of vigilance towards each other. Here, we tested the differential effects of both dyadic agonism and affiliation on the level of social vigilance of group-living western lowland gorillas (Gorilla gorilla gorilla) at Apenheul Primate Park, The Netherlands. We made continuous focal observations of agonistic and affiliative interactions and we scored level of vigilance during neutral approaches of conspecifics. We found that dyads with many affiliative interactions showed lower levels of vigilance towards each other. The opposite pattern was found for agonistic experiences, but this effect was not statistically robust. In addition, the adult male and adolescent males received higher levels of social vigilance than individuals from other age-sex classes. Our results indicate that level of social vigilance was linked to affiliative and, to a lesser extent, agonistic relationships in western lowland gorillas. We suggest that future studies in both egalitarian and despotic species should investigate whether, next to aggression, affiliation also influences social vigilance.

Significance The male-specific Y chromosome harbors genes important for sperm production. Because Y is repetitive, its DNA sequence was deciphered for only a few species, and its evolution remains elusive. Here we compared the Y chromosomes of great apes (human, chimpanzee, bonobo, gorilla, and orangutan) and found that many of their repetitive sequences and multicopy genes were likely already present in their common ancestor. Y repeats had increased intrachromosomal contacts, which might facilitate preservation of genes and gene regulatory elements. Chimpanzee and bonobo, experiencing high sperm competition, underwent many DNA changes and gene losses on the Y. Our research is significant for understanding the role of the Y chromosome in reproduction of nonhuman great apes, all of which are endangered., The mammalian male-specific Y chromosome plays a critical role in sex determination and male fertility. However, because of its repetitive and haploid nature, it is frequently absent from genome assemblies and remains enigmatic. The Y chromosomes of great apes represent a particular puzzle: their gene content is more similar between human and gorilla than between human and chimpanzee, even though human and chimpanzee share a more recent common ancestor. To solve this puzzle, here we constructed a dataset including Ys from all extant great ape genera. We generated assemblies of bonobo and orangutan Ys from short and long sequencing reads and aligned them with the publicly available human, chimpanzee, and gorilla Y assemblies. Analyzing this dataset, we found that the genus Pan, which includes chimpanzee and bonobo, experienced accelerated substitution rates. Pan also exhibited elevated gene death rates. These observations are consistent with high levels of sperm competition in Pan. Furthermore, we inferred that the great ape common ancestor already possessed multicopy sequences homologous to most human and chimpanzee palindromes. Nonetheless, each species also acquired distinct ampliconic sequences. We also detected increased chromatin contacts between and within palindromes (from Hi-C data), likely facilitating gene conversion and structural rearrangements. Our results highlight the dynamic mode of Y chromosome evolution and open avenues for studies of male-specific dispersal in endangered great ape species.

Toni Cade Bambara’s collection of short stories, Gorilla, My Love reveals the revolutionary significance of Black girls’ interior thoughts as an important component of the Black protest tradition. ...

African apes harbor at least twelve Plasmodium species, some of which have been a source of human infection. It is now well established that Plasmodium falciparum emerged following the transmission of a gorilla parasite, perhaps within the last 10,000 years, while Plasmodium vivax emerged earlier from a parasite lineage that infected humans and apes in Africa before the Duffy-negative mutation eliminated the parasite from humans there. Compared to their ape relatives, both human parasites have greatly reduced genetic diversity and an excess of nonsynonymous mutations, consistent with severe genetic bottlenecks followed by rapid population expansion. A putative new Plasmodium species widespread in chimpanzees, gorillas, and bonobos places the origin of Plasmodium malariae in Africa. Here, we review what is known about the origins and evolutionary history of all human-infective Plasmodium species, the time and circumstances of their emergence, and the diversity, host specificity, and zoonotic potential of their ape counterparts.

Objectives The primary aim of this study was to describe the insertion sites of the ligaments holding the flexor digitorum profundus and superficialis muscles (flexor ridges) in proximal phalanges 2-5 of African apes and modern humans. To interpret differences in flexor ridge size based on general behavioral differences among taxa. Materials and methods We analyzed 3D models of manual proximal phalanges 2-5 from 29 gorillas (Gorilla beringei and Gorilla gorilla), 30 chimpanzees (Pan troglodytes) and 36 recent modern humans. Flexor ridges (mm2) were compared within and across genera. Results Gorillas and chimpanzees had larger flexor ridges for phalanges 2-4 than humans and this difference subsists when controlling for body size. Each genus had a unique insertion size pattern across the digits, with the most heterogeneous pattern found in chimpanzees, followed by humans, and lastly gorillas. These patterns corresponded strongly to the differences in the size of the phalanges within each genus, except for phalanx 5 in humans, which had a larger flexor ridge than expected. Discussion When comparing these genera, the flexor ridges signal differences between taxa that use their hands for manipulation and locomotion (gorillas and chimpanzees) and taxa that use them exclusively for manipulation (humans). This functional signal was also apparent in the PP5 of humans, whose larger FR may be indicating the high recruitment of this digit during forceful precision grip characteristic of humans.

The anomalous position of gorillas (Gorilla gorilla gorilla) in the capacity for self-recognition remains puzzling. The standard measure of self-recognition is Gallup's (1970) mark test that assesses an individual's ability to recognize its altered image in a mirror following the application of paint marks to visually inaccessible areas. Here, the results of a small-scale pilot study are presented, utilizing video playback through a TV monitor, to examine behavioral differences indicative of developing self-recognition. The behaviors of 4 Western lowland gorillas at Bristol Zoo, United Kingdom, were observed while watching a TV screen during 5 conditions: blank screen, white noise interference, footage of unfamiliar gorillas, self previously recorded, and self-live. Differences were predicted in the frequency of the gorillas' observed behaviors when viewing each of the conditions: specifically, that there would be more visual inspection, contingent body and facial movements, and self-exploration in the self-recorded and self-live conditions compared with the other conditions. These predictions were partially supported. No agonistic or fear responses were observed, and self-exploration was only seen in the self-live condition. During live playback, contingency-checking movements and self-exploration of the mouth were observed, particularly in the youngest gorilla, providing important video evidence of a close parallel to the mouth exploratory behavior witnessed in self-recognizing chimpanzees. On the basis of these preliminary findings of differentiated spontaneous behaviors, a tentative framework is proposed for categorizing gorillas according to levels of developing self-recognition along a continuum. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Objectives Because trabecular bone volume fraction (BV/TV) is influenced by variations in physical activity recent declines in BV/TV in humans are often attributed to modern sedentary lifestyles. This study tests the hypothesis that presumed variations in mechanical loading between groups can predict the observed BV/TV patterns in humans, chimpanzees and gorillas in two bones: the calcaneus which experiences high and well characterized impact forces, and the C2 vertebrae which experiences reduced locomotor forces. Materials and methods BV/TV and other structural variables were quantified from high-resolution microCT scans in gorillas, chimpanzees, and four Homo sapiens populations: Pleistocene, semi-sedentary Natufians; Holocene hunter-gatherers from Point Hope, Alaska; Holocene nomadic pastoralists from medieval Europe; and modern, sedentary Americans. Results In the calcaneal tuberosity, Natufian BV/TV was 36, 46, and 46% greater than Alaskans (p = .02), Europeans (p = .005) and modern Americans (p = .002), respectively, but not significantly different from apes. BV/TV was not significantly different between modern Americans and Alaskans or Europeans. In the C2, Natufian BV/TV was 53 and 25% greater than in the Alaskan (p = .0001) and European (p = .048) populations. Discussion These results suggest that phenomena other than or in addition to variations in physical activity are needed to explain BV/TV patterns observed in H. sapiens, and point to a systemic decline in H. sapiens BV/TV after the Pleistocene.

Background An obstetrician on standby assessed an 18-year-old primiparous captive gorilla with a term singleton fetus with a protracted labor course. Case After it was determined that an arrest of descent had occurred, a viable, 2,280 g male neonate was delivered through an operative vaginal birth with forceps assistance without major complications. Conclusion Given the numerous anatomic and biochemical similarities of humans and other great apes, it is possible that the high maternal mortality and stillbirth rates of gorillas could be reduced by using the same principles of obstetric management in a multidisciplinary fashion.

Allostatic load is the wear-and-tear organisms accumulate due to senescence and stress; it is measured by combining biomarkers from multiple somatic systems into allostatic load indices (ALIs). Fre...

Food preference has been studied in a range of Hominoidea in the wild and in captivity, allowing for interspecific comparisons. Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla) prefer low-fibre, high-sugar foods, suggesting that frugivory and their dietary overlap are a result of their shared preference for the same nutrients. Comparable tests of the nutritional preference of bonobos do not exist. In this study we examined food preferences of five captive bonobos for 23 familiar and ten novel food items. We performed paired-choice food tests, resulting in a clear rank order in food preference, with minor individual differences. Fruits were more preferred than vegetables. We correlated nutritional composition of the food items with the bonobos' preference. We found that preferences for familiar food items were positively correlated with total energy and carbohydrate content and negatively correlated with water and micronutrient (sodium, calcium, phosphorus, iron, zinc, manganese, selenium) content. Food preference for the novel food items also showed a significant positive correlation with total energy and carbohydrate content. Our study supports the idea that food preference among bonobos follows the pattern of the other great apes and that the shared frugivorous diets may be the result of a common preference for the same nutrients. In the wild, these preferences may be less clear due to the interference of preferred nutrients with secondary compounds. Combining food preference data and nutritional information can help in providing a healthy diet with a balanced nutrient composition in captivity. Individual food preferences can help in optimizing food choice for positive reinforcement training and food-related tasks in future research.

The wild non-human primates that inhabit our planet are experiencing a conservation crisis, with ~60% of all primate species facing extinction and ~75% showing population declines (Estrada et al. 2...

Socioecological variables influence the rate and nature of encounters between conspecific primate groups. Both social (i.e., type of encounter) and ecological factors (i.e., fruit availability) affect rates and outcomes of intergroup encounters in eastern gorillas. However, the roles of individual factors underlying these events among western lowland gorillas (Gorilla gorilla gorilla) remain relatively understudied. We assessed whether group composition (the number of subordinate males and females in the group) and fruit availability influenced the rate of intergroup encounters in three groups of western lowland gorillas in the Republic of Congo. From April 2014 to October 2018, we monitored focal gorilla groups daily in the Goualougo and Djeke Triangles. To assess the ecological similarity between sites, we compared botanical surveys of trees and herbs across them and found overall herb densities were similar between sites. We observed 294 intergroup encounters over 2797 observation days, with a mean rate of 2.20 ± SD 0.93 encounters/month (range: 1.59–3.94) across groups, and these interactions ranged from tolerant to aggressive. The number of subordinate males in the group correlated negatively with the occurrence of intergroup encounters, and groups were more likely to avoid interaction or react aggressively when they encountered a solitary male than when they encountered another group. Some differences between the groups may be attributed to familiarity with extragroup members and the status of the dominant silverback. We found no relationship between the rate of encounters and fruit availability. Our findings indicate that defense of mates, rather than of food resources, may be the most important driver of between-group competition in western lowland gorillas. These findings, which are similar to those for mountain gorillas, suggest that primate social systems may be more variable than previously anticipated within taxa. Therefore, further longitudinal studies are needed to determine the generality of our findings and assess the direct impacts of intergroup encounters on fitness.

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.

Although many animals typically defend key resources from conspecifics during encounters, tolerant encounters also occur frequently in some primate species. For example, African apes and humans (Homininae) show large variation in terms of agonistic and affiliative intergroup relationships, and local human communities are formed via a network of affiliative relationships among groups. To understand this variation and its evolution, we need to examine the variation between species, between populations, and within populations. In the genus Pan, both eastern and western chimpanzees commonly express aggressive intergroup relationships, whereas intergroup relationships in bonobos are generally affiliative. In the genus Gorilla, although the proportions of groups with multiple males differ, all subspecies show large overlap of home ranges and both aggressive and affiliative intergroup interactions. Differences in intergroup relationships among local populations of the same (sub)species are limited in both Pan and Gorilla. In contrast, intergroup relationships vary within the same local populations in bonobos, with female dispersal among groups seemingly contributing to the affiliative relationships. Such tendencies in bonobos seem to resemble those in local human communities, where intergroup relationships differ for different combinations of groups and female dispersal among groups plays an important role in affiliative relationships. Intergroup relationships within the same local populations also vary from affiliative to aggressive in all subspecies of gorillas, and kin relations between leading males play important roles in affiliative relationships. Studies of variation in intergroup relationships, the contributions of males and females to such variation, and the genetic structure of local populations might increase our understanding of the evolutionary process underpinning local communities in Homininae.

Spatial memory allows animals to retain information regarding the location, distribution, and quality of feeding sites to optimize foraging decisions. Western gorillas inhabit a complex environment with spatiotemporal fluctuations of resource availability, prefer fruits when available, and travel long distances to reach them. Here, we examined movement patterns-such as linearity, distance, and speed of traveling-to assess whether gorillas optimize travel when reaching out-of-sight valued resources. Our results show that gorillas travel patterns are affected by the activity they perform next, the type of food they feed on, and their preference level to specific fruits, suggesting they are able to optimize foraging based on spatial knowledge of their resources. Additionally, gorillas left in the direction of the next resource as soon as they started traveling and decelerated before approaching food resources, as evidence that they have a representation of their exact locations. Moreover, home range familiarity did not influence gorillas' movement patterns, as travel linearity in the core and periphery did not differ, suggesting that they may not depend wholly on a network of paths to navigate their habitat. These results show some overlap with chimpanzees' spatial abilities. Differences between the two ape species exist, however, potentially reflecting more their differences in diet (degree of frugivory) rather than their cognitive abilities. Further studies should focus on determining whether gorillas are able to use shortcuts and/or approach the same goal from multiple directions to better identify the spatial abilities used by this species.