Vervet Research Articles

Aping Language: Historical Perspectives on the Quest for Semantics, Syntax, and Other Rarefied Properties of Human Language in the Communication of Primates and Other Animals.

In 1980, Robert Seyfarth, Dorothy Cheney and Peter Marler published a landmark paper in Science claiming language-like semantic communication in the alarm calls of vervet monkeys. This article and the career research program it spawned for its authors catalyzed countless other studies searching for semantics, and then also syntax and other rarefied properties of language, in the communication systems of non-human primates and other animals. It also helped bolster a parallel tradition of teaching symbolism and syntax in artificial language systems to great apes. Although the search for language rudiments in the communications of primates long predates the vervet alarm call story, it is difficult to overstate the impact of the vervet research, for it fueled field and laboratory research programs for several generations of primatologists and kept busy an equal number of philosophers, linguists, and cognitive scientists debating possible implications for the origins and evolution of language and other vaunted elements of the human condition. Now 40-years on, the original vervet alarm call findings have been revised and claims of semanticity recanted; while other evidence for semantics and syntax in the natural communications of non-humans is sparse and weak. Ultimately, we are forced to conclude that there are simply few substantive precedents in the natural communications of animals for the high-level informational and representational properties of language, nor its complex syntax. This conclusion does not mean primates cannot be taught some version of these elements of language in artificial language systems – in fact, they can. Nor does it mean there is no continuity between the natural communications of animals and humans that could inform the evolution of language – in fact, there is such continuity. It just does not lie in the specialized semantic and syntactic properties of language. In reviewing these matters, I consider why it is that primates do not evince high-level properties of language in their natural communications but why we so readily accepted that they did or should; and what lessons we might draw from that experience. In the process, I also consider why accounts of human-like characteristics in animals can be so irresistibly appealing.

Human-Wildlife Conflict around Belo-Bira Forest, Dawro Zone, Southwestern Ethiopia

Human-wildlife conflict (HWC) is a continuous problem in the world and has a significant impact on both human and wildlife populations. This study was conducted to investigate the HWC around Belo-Bira Forest, Dawro zone, southwestern Ethiopia. We collected data from October 2019 to March 2020 through semistructured questionnaires, focus group discussion, direct observation, and key informant interviews. Our results show that crop damage and livestock predation were common problems caused by Papio anubis, Cercopithecus aethiops, Crocuta crocuta, Canis aureus, and Potamochoerus larvatus. Human population growth, habitat disturbance, proximity to natural forest, and competition between wildlife and livestock are the identified causes of HWC. Moreover, the study identified guarding and fencing as dominant traditional methods used to reduce HWC in our study area. Therefore, local communities can minimize crop loss by using the most effective method in an area, and crops such as wheat, maize, and teff should not be grown near the forest edge.

Effect of donor-specific blood transfusions on allotransplanted teeth in a monkey model: Histoquantification of periodontal healing.

Pre-transplant blood transfusions have previously shown a positive effect on organ allograft survival in humans and various animal species. The aims of this study were, first, to evaluate the effect of pre-transplant donor-specific blood transfusions on periodontal healing of fully developed allotransplanted teeth in monkeys; and second, to investigate the immune response against donor antigens and to determine a possible correlation between alloimmune reactions and histopathological signs of rejection. Twenty monkeys (Cercopithecus aethiops) were divided into ten pairs with similar sizes of incisors. One monkey in each pair gave three transfusions to the other monkey with 1-week intervals. One week after the last transfusion, each pair exchanged simultaneously a central maxillary incisor and a lateral mandibular incisor. The corresponding central maxillary and mandibular lateral incisors were autotransplanted to the contralateral sockets. All teeth were treated endodontically per-operatively. Histocompatibility was evaluated by mixed lymphocyte culture before the first transfusion, while alloantibodies and cell-mediated alloresponses were measured before transfusions and at 2 and 8weeks after transplantation. All animals were sacrificed 8weeks after tooth transplantation. Serial sections of the transplanted teeth were quantified histologically. Mixed lymphocyte cultures showed positive reactions in 19 of 20 cases, indicating incompatibility. The majority of the monkeys developed antibodies towards the tooth donor. Cell-mediated cytotoxicity was negative in all monkeys. Histoquantification revealed a mean score of 70% normal periodontal ligament (PDL) in autotransplanted teeth, with 5% ankylosis. The allografts had a mean score of 17% normal PDL and 63% ankylosis, with no significant influence of transfusion. However, in the mandibular grafts, a tendency towards a positive transfusion effect was seen. Donor-specific blood transfusion did not reduce ankylosis in tooth allografts. The healing of mandibular incisor tooth allografts was improved, but not that of maxillary incisors. Donor-specific antibodies showed no effect on the survival of allograft PDL.

Vervet monkeys socialize more when time budget constraints are experimentally reduced

AbstractIn species that live in stable groups, successful management of time budget (i.e., the proportion of time involved in different behaviours) and social relationships has been proposed to be a key variable affecting individual fitness. Such management is limited by time constraints, which are group size and season dependancy. However, the link between time budget constraints and grooming patterns as a means to service social relationships has never been studied experimentally. Here, we reduced the time constraints of three wild vervet monkey (Chlorocebus aethiops pygerythrus) groups by offering them high quality food for 60 min in the morning. We conducted 10 trials in summer and 10 trials in winter. We found that vervet monkeys indeed reduced the proportion of time spent foraging during the rest of those days compared to control days and increased the proportion of grooming time spread over more bouts. Individuals that did not get access to the food still participated as much in grooming as those that did eat. In accordance with our expectations, social network analysis revealed a larger grooming network on supplementation days: vervet monkeys used their extra time to socialize with more different group members. Furthermore, following our predictions, the effect of provisioning was usually stronger during the winter season (when food was scarce and days shorter) than during the summer, and the number of conflicts decreased during supplementation days. Finally, despite the fact that adults and juveniles of all three groups increased their proportion of time spent grooming during supplementation days, few group and age differences emerged in the way vervet monkeys manage their time budget. Interestingly, some of these differences seem to be independent of group size. In conclusion, vervet monkeys seize the opportunity to increase the proportion of time spent in social behaviours if time budget constraints are reduced.

Markers of viral hepatitis E (Hepeviridae, Orthohepevirus, Orthohepevirus A) in the imported Old World monkeys

Viral hepatitis E is a zooanthroponotic disease that occurs in humans and various animals, including monkeys. It is caused by hepatitis E virus (HEV) (Hepeviridae, Orthohepevirus: Orthohepevirus A), for which 8 genotypes have been described to date. Among them, strains of genotypes 1 and 2 have been isolated from humans, strains of genotypes 3 and 4 from humans and animals, and strains of genotypes 5-8 from animals only. The main threat of the disease is associated with the documented zoonotic transmission of HEV genotypes 3, 4, 7, and 8, to humans through infected meat, blood and milk. Thus, monkeys could be involved in the transmission of HEV.The aim of this work was to study serological and molecular genetic markers of HEV infection in strepsirrhines (Old World monkeys, Cercopithecoidea), imported to the Adler Primate Center from various regions of the world (Tanzania, Vietnam, Mauritius). Fecal (n = 224) and blood serum samples (n = 395) from cynomolgus (Macaca fascicularis) and vervet monkeys (Chlorocebus pygerythrus) were examined by the enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). The data obtained show the high detection rate (51.8%) of IgG antibodies to HEV among 5 groups of cynomolgus monkeys imported from Vietnam, with a predominance of highly reactive sera (84%). High detection rate of IgM antibodies in these animals (10.4%) was observed, with the large number of IgM-reactive sera in one particular group of animals (36.8%). The fact of detection of HEV RNA in two groups of cynomolgus monkeys (11.9% and 5.7%) is of particular importance. All HEV sequences of isolated from monkeys belonged to genotype 4. Our data indicate that monkeys (in particular, cynomolgus monkeys) can serve as a natural reservoir of HEV genotype 4 for humans. This requires an appropriate set of anti-epidemic measures in a number of situations.

Occam's razor revisited: guenon species morphology supports evidence for an African influence in Bronze Age Aegean fresco primate iconography from Akrotiri, Thera.

In a recent exchange, Pareja et al. (Primates 61: 159-168, 2020a; Primates 61: 767-774, 2020b) and Urbani and Youlatos (Primates, https://doi.org/10.1007/s10329-020-00825-2 , 2020a) dispute the re-interpretation of the primate species depicted in a Bronze Age fresco from Room 6 of Building Complex Beta at Akrotiri, Thera. They review the history of interpretations of this artwork and combine the expertise of scholars that traditionally focus on such research with the scientific expertise of primatologists to reexamine the artwork. Additionally, they emphasize the morphological traits exhibited by these painted primates. We review and expand their list of candidate primates here in a decision table to demonstrate that the African link is better supported by the morphological traits than the Asian one proposed by Pareja et al. (2020a, b). Using such evidence, we show that other guenons of the tribe Cercopithecini, such as L'Hoest's monkey (Allochrocebus lhoesti) and the Diana monkey (Cercopithecus diana), provide equal support for the African link as the vervet monkey proposed by Urbani and Youlatos (2020a). However, the historical context supports the traditional interpretation that the Akrotiri fresco depicts vervet monkeys from this region. This discourse provides an open forum for scholars in various fields to contribute to an important problem that crosses disciplinary boundaries.

Impacts of habitats and seasons on mammalian diversity and distribution in the Faragosa-Fura landscape, Gamo Zone, Southern Ethiopia

ABSTRACT In Ethiopia, most of the studies on mammals have focused on single species and protected areas. This survey investigated the impacts of habitats and seasons on the medium and large-sized mammals’ diversity and distribution in a human-dominated landscape. This survey was conducted using 36 systematically distributed transect lines within stratified habitat types. A total of 685 records belonging to 21 species, six orders, and 13 families were identified, including globally vulnerable Panthera leo, Panthera pardus, and Hippopotamus amphibious. Overall, Papio anubis and Chlorocebus aethiops were the dominant species recorded in the area. Except for three species, all species encountered in the three habitats are subsets of the species recorded in the grassland. The species record frequency was highest in the forest. The dry season characterized by a higher frequency of records but by lower species richness than the wet season. In general, the study area is potential for mammalian species conservation in Ethiopia.

Serological Evidence of Filovirus Infection in Nonhuman Primates in Zambia.

Ebolaviruses and marburgviruses are filoviruses that are known to cause severe hemorrhagic fever in humans and nonhuman primates (NHPs). While some bat species are suspected to be natural reservoirs of these filoviruses, wild NHPs often act as intermediate hosts for viral transmission to humans. Using an enzyme-linked immunosorbent assay, we screened two NHP species, wild baboons and vervet monkeys captured in Zambia, for their serum IgG antibodies specific to the envelope glycoproteins of filoviruses. From 243 samples tested, 39 NHPs (16%) were found to be seropositive either for ebolaviruses or marburgviruses with endpoint antibody titers ranging from 100 to 25,600. Interestingly, antibodies reactive to Reston virus, which is found only in Asia, were detected in both NHP species. There was a significant difference in the seropositivity for the marburgvirus antigen between the two NHP species, with baboons having a higher positive rate. These results suggest that wild NHPs in Zambia might be nonlethally exposed to these filoviruses, and this emphasizes the need for continuous monitoring of filovirus infection in wild animals to better understand the ecology of filoviruses and to assess potential risks of outbreaks in humans in previously nonendemic countries.

On the problem of craniological differentiation in two species of the green monkeys: Chlorocebus pygerythrus and C. aethiops (Cercopithecidae, Primates)

The problem of taxonomic differentiation in the order Primates is one of the important problems of evolutionary anthropology and primatology. The systematics of primates reflects their evolutionary relationships and allows to reconstruct the possible ways of formation of particular groups. Clarification of primate taxonomy involves a wide range of data, primarily from the field of morphology. Among the morphological features that distinguish particular taxa, the special role belongs to the system of craniological characters, which allow diagnosing the skulls in museum collections or fossil materials. The article is devoted to craniological identification of two species of the genus Chlorocebus: Chlorocebus pygerythrus (vervets) and Chlorocebus aethiops (grivets).

Presence of the Endocannabinoid System in the Inferior Pulvinar of the Vervet Monkey.

The expression of the endocannabinoid (eCB) system, including cannabinoid receptor type 1 (CB1R) and the cannabinoid synthesizing (NAPE-PLD) and degrading (FAAH) enzymes, has been well-characterized in the retina of rodents and monkeys. More recently, the presence of CB1R was localized throughout the dorsal lateral geniculate nucleus of the thalamus of vervet monkeys. Given that the retina projects also to the pulvinar either via a direct projection or via the superior colliculus, it was reasonable to assume that this system would be present therein. The visual pulvinar, namely the inferior pulvinar (PI) region, was delineated with calbindin immunohistochemical staining. Using Western blots and immunofluorescence, we demonstrated that CB1R, NAPE-PLD and FAAH are expressed in the PI of the vervet monkey. Throughout the PI, CB1R was mainly colocalized with VGLUT2-positive axon terminals in the vicinity of calbindin and parvalbumin-positive neurons. NAPE-PLD and FAAH rather colocalized with calbindin over the somatodendritic compartment of PI neurons. Our results suggest that visual information coming from the retina and entering the PI is modulated by the eCB system on its way to the dorsal visual stream. These results provide insights for understanding the role of eCBs in the modulation of visual thalamic inputs and, hence, visual perception.

Factors affecting tolerance persistence after grooming interactions in wild female vervet monkeys, Chlorocebus pygerythrus

Grooming is the most common cooperative behaviour in primates. It has helped advance our understanding of how animals achieve reciprocal cooperation without using precise counting strategies. For example, attitudinal reciprocity refers to recipients making short-term adjustments like reciprocated grooming or tolerance at food sources based on a change in emotional states. Here, we used an experimental set-up to investigate in unprecedented detail the building blocks of attitudinal reciprocity that govern wild dominant females' tolerance around food after a grooming interaction with a subordinate female partner in vervet monkeys. We measured the tolerance of dominant females towards the previous grooming partner within 4 h after a grooming interaction. Tolerance levels remained elevated compared to baseline for the entire period, decreasing with time and predicted to fall to baseline levels after approximately 6 h. The decline in tolerance was not affected by the relationship quality between females, further grooming received from other group members or the surplus grooming that the dominant received relative to what she gave. However, the duration of grooming by the subordinate influenced the dominant's tolerance positively. These results suggest that the temporal dynamics of tolerance are best described as grooming triggering the start of a partner-specific ‘hourglass’, where the amount of remaining ‘sand’ equates to the dominant's current tolerance level above baseline. The results challenge the notion that dominants use scorekeeping regarding their grooming debts towards subordinates to make decisions about reciprocating with tolerance.

Processing of novel food reveals payoff and rank-biased social learning in a wild primate

Social learning—learning from others—is the basis for behavioural traditions. Different social learning strategies (SLS), where individuals biasedly learn behaviours based on their content or who demonstrates them, may increase an individual’s fitness and generate behavioural traditions. While SLS have been mostly studied in isolation, their interaction and the interplay between individual and social learning is less understood. We performed a field-based open diffusion experiment in a wild primate. We provided two groups of vervet monkeys with a novel food, unshelled peanuts, and documented how three different peanut opening techniques spread within the groups. We analysed data using hierarchical Bayesian dynamic learning models that explore the integration of multiple SLS with individual learning. We (1) report evidence of social learning compared to strictly individual learning, (2) show that vervets preferentially socially learn the technique that yields the highest observed payoff and (3) also bias attention toward individuals of higher rank. This shows that behavioural preferences can arise when individuals integrate social information about the efficiency of a behaviour alongside cues related to the rank of a demonstrator. When these preferences converge to the same behaviour in a group, they may result in stable behavioural traditions.

The expression of type I and II gonadotropin-releasing hormone receptors transcripts in Vervet monkey (Chlorocebus aethiops) spermatozoa

Gonadotropin-Releasing Hormone (GnRH), acting via the GnRH receptor (GnRHR), and a member of G-protein coupled receptor (GPCR), plays an essential role in the control of reproduction while operating primarily at the hypothalamic level of the gonadotropic axis. GnRH and its receptor are co-expressed in certain specific cells, suggesting an autocrine regulation of such cells. In the male reproductive system, two forms of GnRH (I and II) and its receptors (GnRHR) are present in the human and non-human primate (NHP) testis, prostate, epididymis, seminal vesicle, and human spermatozoa. In humans, the GnRHR-II receptor gene is disrupted by a frameshift in exon 1 and a stop codon in exon 2, rendering the receptor non-functional, whereas a fully functional GnRHR-II receptor is present in New-World and Old-World monkeys. There is no evidence of the existence of a GnRH receptor in NHP sperm. Since the NHP has a phylogenetic relationship to man and is often used as models in reproductive physiology, this present study aimed to determine GnRHR-I and GnRHR-II in Vervet monkey (Chlorocebus aethiops) spermatozoa. A total of 24 semen samples were obtained from four adult Vervet monkeys through electro-ejaculation and utilized for genotyping and gene expression analysis of GnRHR-I and II. Here we report that both receptors were successfully identified in the Vervet monkey sperm with the abundance of GnRHR-I gene expression compared to GnRHR-II. In comparison to the human, there is no evidence of such a stop codon at position 179 in exon 2 of the Vervet GnRHR-II. These findings suggest that both receptors are transcriptionally functional in Vervet spermatozoa.

Reprint of: Relationship Between Surface and Inflammatory Resorption and Changes in the Pulp After Replantation of Permanent Incisors in Monkeys

The etiology of surface and inflammatory root resorption after the replantation of incisors was examined in green vervet monkeys. The teeth were examined histologically and histobacteriologically for pulpal healing and root resorption 2 and 8 weeks after replantation. In contrast to surface resorption, inflammatory resorption was related to infected necrotic tissue or an infected leukocyte zone in the root canal. The following theory for surface and inflammatory resorption is presented. Damaged periodontal ligament areas and damaged parts of the root surface are attacked by a resorption process whereby resorption of cementum and dentin may occur. Inflammatory resorption or surface resorption will then occur depending on the pulpal status and the depth of the resorption cavity. If the resorption cavity penetrates the intermediate layer of cementum and contacts dentinal tubules that are in communication with infected necrotic pulp tissue or an infected leukocyte zone, then inflammatory resorption will take place as a result of the diffusion of toxic elements from the pulp canal to the resorption cavity. However, if the resorption cavity is shallow and does not penetrate the intermediate layer of cementum, a tooth that displays similar pulpal changes will elicit only surface resorption because the intermediate layer of cementum will tend to arrest the diffusion of toxic elements. Finally, if the pulp contains vital, inflamed, or noninflamed tissue or if root canal treatment has been performed, surface resorption will occur regardless of the depth of the cavity.

Female African Green Monkeys Exhibit Higher Insulin Sensitivity and Lower Blood Pressure than Age‐matched Males

Type 2 Diabetes (T2DM) has become the most prevalent form of diabetes worldwide. In some studies, females have increased insulin sensitivity with greater glucose tolerance than males. Pre-menopausal females may also be protected from early onset T2DM, hypertension and early onset end stage renal disease. A subpopulation of African Green Monkeys (AGM; Chlorocebus aethiops sabaeus) exhibit spontaneous glucose intolerance and co-morbidities such as insulin insensitivity, and spontaneous hypertension. The AGM’ similarities to human pathologies make them an optimal experimental model for diabetes. Thus, we hypothesize that female AGM may differ in insulin sensitivity compared to age-matched males. Healthy, middle-aged AGM were utilized (n= 22 female, n=13 male). Systolic blood pressure (SBP) was measured by forearm plethysmography. Glucose tolerance was assessed via conscious and anesthetized oral glucose tolerance tests (OGTT). All AGM were fasted 12-18 hours with water provided ad libitum. Blood glucose was measured via standard glucometry at 0, 15, 30, 60, 90, and 120 min after an oral glucose load. Conscious AGM’ OGTT were delivered as 0.75g glucose/kg body weight. Anesthetized AGM (ketamine, 15mg/kg, i.m.), received 5g/dl glucose and 15 ml/kg in water. Venous blood samples were taken at 0, 30, 90 and 120 min after glucose administration in anesthetized AGM. All data between conscious and anesthetized OGTT were similar. All AGM were normotensive, however, male SBPs averaged 117.6 ± 4.2 mmHg compared with female SBPs of 104.1 ± 4.1 mmHg (p< 0.05). Female AGM area under the curve (AUC) for glucose was 12,102±466.9 min*mg/dl compared to 13,799.4±564.1 min*mg/dl for males over the 120 min after the glucose load. The peak blood glucose AUC response for females was 6,211.4 ± 219.5 min*mg/dl and 7,482 ±600.1 min*mg/dl in males (p<0.05). Insulin and C-peptide were also compared at the same time points. There were no differences in insulin or C-peptide responses between males and females. Overall renal glomerular function was assessed by measuring fasted, plasma creatinine concentrations. Average plasma creatinine was not different between males and females. These data demonstrate that middle-aged, males have decreased glucose tolerance compared to age-matched females despite similar OGTT induced changes in plasma insulin and C-peptide. Thus, middle-aged males have decreased insulin sensitivity in their response to glucose following an oral glucose load compared to females. All AGM in this study were normotensive however, females had significantly lower SBP than males, indicating that reduced glucose tolerance in males may contribute to elevated SBP. Together, the glucose and SBP data may suggest early onset of T2DM in males compared to age-matched females. This potential early onset T2DM has yet to induce overt alterations in renal glomerular filtration. Long-term studies are needed to assess whether further blood pressure elevation can lead to a decline in renal function and renal injury. Future studies will include differentiation of renal function in males and females including proteinuria, glomerular filtration, and kidney histology of AGM.

Be early or be tolerated: vervet monkey, Chlorocebus pygerythrus, foraging strategies in a dispersed resource

Among social foragers, individuals can actively search for and find food (the producers) or join already discovered food patches (the scroungers). Compared to scroungers, producers often occupy more dangerous outer spatial positions in the group, but they benefit from the finder's advantage, which is the amount of food eaten before the arrival of others. Scroungers may occupy safer positions but they face feeding competition when joining a patch already occupied by others. Here, we report factors influencing intragroup spatial position, feeding strategies and feeding success for a group of wild vervet monkeys, C. pygerythrus, at Lake Nabugabo, Uganda. We collected data using behavioural observations and field experimentation (N = 132 trials) where we set up an artificial food patch with dispersed food rewards. We found that individuals who spent more time in the front-outer position of a moving group produced more. Producers that had a greater finder's time advantage (fed undetected by group members for longer periods) had a greater finder's advantage (consumed more food items before the arrival of other group members), and scroungers that arrived earlier had greater overall feeding success. We found that when the scrounger was higher ranking than other individuals at the patch, they used displacement scrounging (supplanted at least one individual from the patch to gain access to the food resource). However, feeding success did not differ between displacement scrounging and tolerated scrounging (when the scrounger fed at the patch with at least one other individual). Interestingly, we did not find higher-ranking individuals to have greater feeding success than lower-ranking individuals. Our findings corroborate previous studies showing that even among species with a linear dominance hierarchy and high occurrences of within-group contest competition, dominant individuals do not benefit from feeding advantages at large, dispersed food patches since they cannot monopolize the resource. Furthermore, our results emphasize the need to understand factors influencing feeding tolerance, particularly for subordinate individuals, who need to process ecological and social elements to maximize their food acquisition.

Social contact behaviors are associated with infection status for Trichuris sp. in wild vervet monkeys (Chlorocebus pygerythrus).

Social grooming in the animal kingdom is common and serves several functions, from removing ectoparasites to maintaining social bonds between conspecifics. We examined whether time spent grooming with others in a highly social mammal species was associated with infection status for gastrointestinal parasites. Of six parasites detected, one (Trichuris sp.) was associated with social grooming behaviors, but more specifically with direct physical contact with others. Individuals infected with Trichuris sp. spent significantly less time grooming conspecifics than those not infected, and time in direct contact with others was the major predictor of infection status. One model correctly predicted infection status for Trichuris sp. with a reliability of 95.17% overall when the variables used were time spent in direct contact and time spent grooming others. This decrease in time spent grooming and interacting with others is likely a sickness behavior displayed by individuals with less energy or motivation for non-essential behaviors. This study emphasizes the possible links between host behavior and parasitic infections and highlights the need for an understanding of a study population's parasitic infections when attempting to interpret animal behavior.

Further away with dental microwear analysis: Food resource partitioning among Plio-Pleistocene monkeys from the Shungura Formation, Ethiopia

This study aims at improving dietary discrimination among primates through a new analytic approach of dental microwear texture analysis integrating a surface sampling on facets of both phase I and II of mastication. The surface sampling is applied on these two types of molar facets on 104 specimens belonging to four extant cercopithecids, and on 207 Plio-Pleistocene specimens representing four taxa from the Shungura Formation, Ethiopia. The extant species, including Colobus guereza, Theropithecus gelada, Papio hamadryas, Chlorocebus aethiops, compose a model covering a wide range of feeding ecology from leaf-eating through grass-eating habits to opportunistic habits.A principal component analysis built with a selection of the most discriminant variables and extant species as a model displays that the two facets contribute equally to the dispersion of individuals and to the between-species differences. Also, most contributing variables along the components are not central values of texture parameters (mean and median of the parameters measured on subsurfaces or a single value for the whole surface) but rather statistics of their dispersion (percentiles) and distribution (kurtosis, skewness).Once the fossil specimens are inserted into the extant species model, the two large-bodied colobines, Paracolobus and Rhinocolobus, are found to differ from the extant Colobus guereza, one of the most leaf-eating colobines. This highlights ecological diversity among early African colobines. Besides, the analysis tracks between-genus as well as temporal differences between the extinct species of papionins, attesting of a low ecological overlapping between Theropithecus and non-theropith papionins, notably after 2.4 Ma. No significant difference was found between T. brumpti, T. oswaldi, Theropithecus sp. supporting similar feeding habits with the present-day gelada, at least from 2.9 Ma onwards.

Efficiency of whole-exome sequencing in old world and new world primates using human capture reagents.

Whole-exome sequencing (WES) can expedite research on genetic variation in non-human primate (NHP) models of human diseases. However, NHP-specific reagents for exome capture are not available. This study reports the use of human-specific capture reagents in WES for olive baboons, marmosets, and vervet monkeys. Exome capture was carried out using the SureSelect Human All Exon V6 panel from Agilent Technologies, followed by high-throughput sequencing. Capture of protein-coding genes and detection of single nucleotide variants were evaluated. Exome capture and sequencing results showed that more than 97% of old world and 93% of new world monkey protein coding genes were detected. Single nucleotide variants were detected across the genomes and missense variants were found in genes associated with human diseases. A cost-effective approach based on commercial, human-specific reagents can be used to perform WES for the discovery of genetic variants in these NHP species.

Female emancipation in a male dominant, sexually dimorphic primate under natural conditions.

In most group-living animals, a dominance hierarchy reduces the costs of competition for limited resources. Dominance ranks may reflect prior attributes, such as body size, related to fighting ability or reflect the history of self-reinforcing effects of winning and losing a conflict (the winner-loser effect), or both. As to prior attributes, in sexually dimorphic species, where males are larger than females, males are assumed to be dominant over females. As to the winner-loser effect, the computational model DomWorld has shown that despite the female’s lower initial fighting ability, females achieve some degree of dominance of females over males. In the model, this degree of female dominance increases with the proportion of males in a group. This increase was supposed to emerge from the higher fraction of fights of males among themselves. These correlations were confirmed in despotic macaques, vervet monkeys, and in humans. Here, we first investigate this hypothesis in DomWorld and next in long-term data of 9,300 observation hours on six wild groups of robust capuchin monkeys (Sapajus libidinosus; S. nigritus, and S. xanthosternos) in three Brazilian sites. We test whether both the proportion of males and degree of female dominance over males are indeed associated with a higher relative frequency of aggression among males and a higher relative frequency of aggression of females to males. We confirm these correlations in DomWorld. Next, we confirm in empirical data of capuchin monkeys that with the proportion of males in the group there is indeed an increase in female dominance over males, and in the relative frequency of both male-male aggression and aggression of females to males and that the female dominance index is significantly positively associated with male male aggression. Our results reveal that adult sex ratio influences the power relation between the sexes beyond predictions from socioecological models.