Correlation between musculoskeletal structure of the hand and primate locomotion: Morphometric and mechanical analysis in prehension using the cross- and triple-ratios.

Biometric ratios of the relative length of the rays in the hand have been analyzed between primate species in the light of their hand function or phylogeny. However, how relative lengths among phalanges are mechanically linked to the grasping function of primates with different locomotor behaviors remains unclear. To clarify this, we calculated cross and triple-ratios, which are related to the torque distribution, and the torque generation mode at different joint angles using the lengths of the phalanges and metacarpal bones in 52 primates belonging to 25 species. The torque exerted on the finger joint and traction force of the flexor tendons necessary for a cylindrical grip and a suspensory hand posture were calculated using the moment arm of flexor tendons measured on magnetic resonance images, and were compared among Hylobates spp., Ateles sp., and Papio hamadryas. Finally, the torques calculated from the model were validated by a mechanical study detecting the force exerted on the phalanx by pulling the digital flexor muscles during suspension in these three species. Canonical discriminant analysis of cross and triple-ratios classified primates almost in accordance with their current classification based on locomotor behavior. The traction force was markedly reduced with flexion of the MCP joint parallel to the torque in brachiating primates; this was notably lower in the terrestrial quadrupedal primates than in the arboreal primates at mild flexion. Our mechanical study supported these features in the torque and traction force generation efficiencies. Our results suggest that suspensory or terrestrial quadrupedal primates have hand structures that can exert more torque at a suspensory posture, or palmigrade and digitigrade locomotion, respectively. Furthermore, our study suggests availability of the cross and triple-ratios as one of the indicators to estimate the hand function from the skeletal structure.

Parameters of Experimental Activity in the Study of the Cognitive Abilities of Rhesus Monkeys (Macaca mulatta) and Baboons (Papio hamadryas).

We compared experimental activity, behavioral activity in the experiment, of rhesus monkeys (Macaca mulatta) and baboons (Papio hamadryas). Baboons showed higher levels of experimental activity. The contrast in the activity between the species is probably associated with species-specific characteristics of the behavior and different ability to adapt under new conditions. In particular, they may be the result of lower plasticity of rhesus monkeys with respect to experimental conditions.

Meat eating in wild hamadryas baboons: Opportunistic trade-offs between insects and vertebrates.

The consumption of meat may provide herbivorous animals with important nutrients that are scarce in their plant-based diet. Seasonal variation in plant food availability has been suggested to motivate dietary flexibility in a range of species and thus primates may seek more prey when key plant resources are unavailable. Alternatively, prey encounter rate may drive meat eating. Here we investigate patterns of meat eating in hamadryas baboons (Papio hamadryas) at Filoha, Awash National Park, Ethiopia. The Filoha baboons rely largely on doum palm fruit (Hyphaene thebaica), which are available most months of the year, and the young leaves of Acacia senegal, which are more abundant during the wet season. We hypothesized that the baboons would consume more meat when H. thebaica and A. senegal were less available, which we tested by comparing meat eating and consumption of these plant food species from March 2005 through February 2006. Our results reveal a high rate of vertebrate meat eating at Filoha (0.028/hour of observation) compared with other hamadryas sites. We found no relationship, however, between meat eating (either insect or vertebrate) and either rainfall or consumption of H. thebaica or A. senegal, indicating that availability of preferred plant resources does not drive meat consumption. Vertebrate consumption and time spent feeding were significantly negatively associated; there was no relationship, however, between the consumption of animal matter and either home range size or daily path length. Vertebrate and insect consumption alternated throughout the year such that the baboons maintained a small amount of animal matter in their diet year-round. Our results suggest that the baboons do not often actively seek animal matter, but consume it opportunistically, with the presence of locust and dragonfly swarms driving insect consumption, and both prey availability and the availability of feeding time shaping vertebrate predation.

Correlation of Cognitive Abilities of Male Hamadryas Baboon with Age and Hierarchical Status.

We studied the correlation between the rank and age of baboons (n=12) with their cognitive abilities. A positive correlation was found between performances of different tests by male. The ability to solve the tests related to bait placement depended on the age of the males and age-related hierarchical status. Four-year-old males performed these tests in 52% of cases, whereas five-year-old males, who reached a higher hierarchical status by this age solved with them in 93% of cases. In the tests for exploratory activity and the ability to learn skills, the differences between the four-year-olds and the five-year-old males are not received.

Effect of menstrual cycle phase and hormonal treatments on evaluation of tubal patency in baboons.

BACKGROUND: We evaluated whether menstrual cycle phase influences the assessment of tubal patency by hysterosalpingography (HSG) in baboons. METHODS: Retrospective analysis of baseline tubal patency studies and serum estradiol (E2 ) and progesterone (P4) values obtained from female baboons used as models for development of non-surgical permanent contraception in women. The main outcome measure was bilateral tubal patency (BTP) in relationship with estradiol level. RESULTS: Female baboons (n = 110) underwent a single (n = 81), two (n = 26), or three (n = 3) HSG examinations. In 33/142 (23%) HSG examinations, one or both tubes showed functional occlusion (FO). The median E2 in studies with BTP (49 pg/mL) was significantly higher than in those studies with FO (32 pg/mL, P = .005). Among 18 animals with repeat examinations where serum E2 changed from <60 to ≥ 60 pg/mL, 13 results changed from FO to BTP (P = .0001). No sets showed a change from BTP to FO with an increase in estradiol. CONCLUSION: In baboons, functional occlusion of the fallopian tube is associated with low estradiol levels, supporting a role for estrogen-mediated relaxation of the utero-tubal junction.

Group compositional changes impact the social and feeding behaviors of captive hamadryas baboons (Papio hamadryas hamadryas).

The formation and modification of social groups in captivity are delicate management tasks. The ability for personnel to anticipate changes in group dynamics following compositional changes can increase the likelihood of successful management with minimized injury or social instability. Hamadryas baboons (Papio hamadryas hamadryas) have a distinctive multi-level social system comprising of one-male units (OMUs) that can make it difficult to apply knowledge from other primates' multi-female/multi-male social structure to changes imposed onto captive hamadryas baboon groups. We conducted an observational study of the behavioral impacts following the introduction of two females into the group of hamadryas baboons at the Wildlife Conservation Society's Prospect Park Zoo in NY to test hypotheses about the relationships between changes in group composition and social and feeding behavior. Generalized linear mixed models demonstrated that social interactions significantly increased following the compositional changes, even in groups that only experienced member removals. The increase in affiliative social behavior observed suggests that during times of social stress or uncertainty, hamadryas baboons may employ social behavior as a tension-reducing mechanism to negotiate relationships as opposed to using aggression to engage in competitions for ranks and resources. The observed response to compositional changes implies that hamadryas baboons may respond with less aggression than do other Old World monkey species and that levels of affiliative behavior may be a more accurate metric for evaluating introduction success in hamadryas baboons.

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Activity rhythms and time budgets are two important components of ecological influences on animal individual behaviors. We collected data on activity pattern using instantaneous scan sampling on captive hamadryas baboons (Papio hamadryas) in Hangzhou Wild Animal Zoo in Zhejiang, China from November 2012 to October 2013. The results showed that: 1) In the activity time allocation, the main activities (frequency percentage was more than or equal to 5%) included resting (42.5%), traveling (16.2%), playing (10.0%), feeding (9.8%), grooming (9.4%) and watching (7.3%), and the secondary activities (frequency percentage is lower than 5%) only accounted for a total of 4.8%. 2) Due to increasing in the feeding and watching time, and decreasing in the playing and grooming time in winter, their time budgets showed significant seasonal variation, but the resting and swimming time had no significant difference between the cold season and the warm season. 3) The diurnal activity rhythms of P. hamadryas showed two feeding peaks of morning and afternoon, and as the temperature gradually turned cold, feeding activity gradually increased with three feeding peaks, which might be a strategy of complementary energy against the cold season. 4) P. hamadryas only had a midday resting and grooming peak with multi peaks of traveling and playing in the warm season, and the swimming, playing and watching time rhythm had not obvious difference between the cold winter and the warm season, but there were multi peaks of resting in the cold winter. Therefore, their diurnal activity rhythm was not the same as other many primates (such as Nomascus nasutus, Propithecus verreauxi and Lagothrix sp.), the captive P. hamadryas in winter in Hangzhou area took a strategy of feeding for supplement energy to withstand cold rather than resting to reduce energy consumption. In short, Papio hamadryas reflects obvious rhythm with seasonal differences, which may be an adaptation to the influence of food and temperature changes in captivity.

The adaptive value of secondary males in the polygynous multi-level society of hamadryas baboons.

OBJECTIVES: One-male social systems are usually characterized by polygyny and reproductive exclusion by a single resident male. Sometimes, however, secondary males join these groups, and this may carry fitness costs and/or benefits to the resident male. In hamadryas baboons (Papio hamadryas hamadryas), which live in one-male units (OMUs) with female defense polygyny within a multi-level social system, secondary "follower" males often reside in OMUs. Our aim here is to examine possible benefits of these secondary males to hamadryas resident males. MATERIALS AND METHODS: Using 6 years of data from 65 OMUs in a band of wild hamadryas baboons in Ethiopia, we compared demographic and reproductive parameters of OMUs with and without secondary "follower" males to assess whether their presence conferred any reproductive benefits to resident "leader" males. RESULTS: Leaders with followers had tenure lengths almost twice as long, acquired more than twice as many females, retained females longer, and had three times as many infants during their tenure compared to leaders without followers. DISCUSSION: Hamadryas follower males enabled leaders to retain females for longer periods of time-likely through unit defense, social relationships with OMU members, and/or infant protection. Hamadryas leaders appear to be able to monopolize access to females despite the presence of followers, and as such any enhanced reproduction derived from the presence of followers likely increases the fitness of the leader rather than the follower. Thus the relationship between leaders and followers in hamadryas society appears to be a mutually beneficial one and tolerance of secondary males may be an adaptive reproductive strategy characterizing hamadryas leader males.

Variation of hair cortisol concentrations among wild populations of two baboon species (Papio anubis, P. hamadryas) and a population of their natural hybrids.

Male olive (Papio anubis) and hamadryas (P. hamadryas) baboons have distinctive sociobehavioral and physical characteristics. In the Awash National Park, Ethiopia, a hybrid population at the contact zone between these two species, exhibits heterogeneous sociobehavioral and physical characteristics. The ambiguity of the hybrid social environment and disruption of parental stress genotypes may be sources of physiological stress for hybrids. We examined levels of chronic stress among males of the three populations and tested the prediction that chronic cortisol levels would be higher among the hybrids. Animals were captured, sampled, and released during the wet season, and a hair sample was taken for assay. Cortisol was extracted from 182 hair samples with methanol and quantified by ELISA. We included age, age class, rainfall variation, and species affiliation in models examining variation in hair cortisol levels. Species and age significantly contributed to models explaining variation in hair cortisol. Infant hypercortisolism was observed in all three groups, and a decline in cortisol through juvenile and adolescent stages, with a subsequent rise in adulthood. This rise occurred earliest in hamadryas, corroborating other evidence of the precocious development of hamadryas baboons. As expected, hybrids had significantly elevated hair cortisol compared with olive baboons and hamadryas, irrespective of age, except for very young animals. Infant hypercortisolism was also less pronounced among hybrids. Species differences and age-related differences in cortisol levels suggest a dysregulated cortisol phenotype in hybrids, and possibly reflect some form of hybrid disadvantage. More work will be required to disentangle the effects of genetic factors and the social environment.

[The ability of hamadryas baboons' adolescents to decide the modified Piaget's A-not-B error test].

We investigated the ability to the inhibition of a forced instrumental food-procuring reflex in hamadryas baboons (Papio hamadryas). The subjects of the study were immature animals of the two age groups: the eighteen-month-old group (six males and five females) and three-year-old group (seven males and seven females). To determine the capability we used the modified Piaget's A-not-B error test. Four monkeys correctly decided the test only. The inhibition of the forced conditioned reflex occurred in females only and in the equal degree in each age group. The findings also show the big variation in an activity among the individuals of the different sex and age during the decision of the task. Regarding animals have shown the ability to inhibit consolidation of the conditioned reflex, we tend to treat it as a manifestation of conscious choice, but more research is needed.

Male takeovers are reproductively costly to females in hamadryas baboons: a test of the sexual coercion hypothesis.

During male takeovers, in addition to fighting off the female's current mating partner, males may exhibit intense aggressive mate guarding of the newly acquired females. Recent studies indicate that coercive sexual aggression by males is an important strategy through which sexual conflict is expressed. Previous tests of the sexual coercion hypothesis in primates have focused on assessing if female mate choice is effectively reduced by male aggression, however, only one recent study has tested a critical prediction of this hypothesis, namely, that male coercion is reproductively costly to victim females. The present study uses 15 years of data on inter-birth intervals from a large multilevel colony of baboons, mostly Papio h. hamadryas, with a mating system based on harem-defence polygyny to examine if male takeovers impact the length of the abducted females' inter-birth intervals. Our analysis of 121 inter-birth intervals from 45 adult females indicates that male takeovers are reproductively costly to abducted females as they are associated with an increase in the time they take to conceive and a lengthening of the inter-birth intervals. We discuss how several factors may contribute to this reproductive cost, including male-female sexual conflict, male-male competition, and female-female competition. Our findings suggest that the male's aggressive herding is the main contributor to the abducted females' immediate reproductive cost. We argue that although some of the male's aggressive herding may be driven by male-male competition, nonetheless, it serves a coercive function as it both constrains the female's mate choice options and hampers her immediate breeding performance. This conclusion is backed up by results obtained in the only other study that has tested the same prediction and which has been carried out in a wild population of hamadryas baboons.

[Redirection and consolation in hamadryas baboons].

Post-conflict interactions between victims and non-involved group members was investigated in the troop of hamadryas baboons, Papio hamadryas. Observations were done in the Russian Primate Center, Adler in 1996-1997. Redirected aggression, initiation of affiliation from the side of victims towards third parties and consolation were registered during this study. The analyses was done on 445 PC-MC pairs of animals, represented different social classes (harem male-female pairs, harem females, relations, females from different harems, male-male pairs, female-subadult pairs). The attracted-pairs method and the time-rule method were used. Redirected aggression was practiced mainly by male aggressees. It was typical for victims, both males and females, to initiate affiliative interactions with third parties soon after the conflict. Consolation was practiced by hamadryas baboons, but it was limited to harem male-female pairs only. Special affiliative patterns were used by male-consoler. This is the first case, when consolation was demonstrated in baboons.

Ecology and sociality in a multilevel society: ecological determinants of spatial cohesion in hamadryas baboons.

The multilevel society of hamadryas baboons, consisting of troops, bands, clans, and one-male units (OMUs), is commonly perceived to be an effective means of adapting to variable food availability while allowing spatial cohesion in response to predator pressure. The relationship between these variables, however, has never been tested quantitatively. The Filoha site in Awash National Park, Ethiopia is ideally suited to such an investigation as it contains nutrient-dense palm forests in addition to the Acacia scrublands typical of hamadryas distribution elsewhere, allowing comparisons of spatial cohesion across habitat types. Here, we use observations over a 1-year period to examine the relationship between resource availability, perceived predator pressure, and spatial cohesion in a band of wild hamadryas baboons at Filoha. Our results demonstrate that the band was more likely to break into OMUs when foraging in habitats with lower food availability, and that the band fissioned into independent clans more often when preferred resources were not available. Furthermore, the baboons remained in larger aggregations for longer periods of time (i.e., prior to embarking on their daily foraging route) on mornings after predators were heard in the vicinity, and increased cohesion in response to encounters with people who may have been perceived as predators. These results support the notion that hamadryas baboons change their social groupings in response to both food availability and predation risk and that the ability of hamadryas bands to cleave and coalesce in response to changes in these factors underlies the evolution of the hamadryas modular social structure.

Haemodynamics using transthoracic echocardiography in healthy pregnant and non-pregnant baboons (Papio hamadryas).

BACKGROUND: To determine systolic and diastolic function using transthoracic echocardiography in the baboon (Papio hamadryas). METHODS: Transthoracic echocardiography was performed in eight non-pregnant female and six pregnant baboons according to American Society of Echocardiography recommendations. RESULTS: Haemodynamic measurements were obtained from fourteen baboons. Compared to non-pregnant baboons, pregnant baboons demonstrated: (mean ± SD, pregnant vs. healthy) increased cardiac output (1615 ± 121 ml/minutes vs. 1317 ± 134 ml/minutes P = 0.001) due to an increased heart rate [120 ± 11 beats per minute (BPM) vs. 105 ± 6 BPM P = 0.018]. The inter-observer and intra-observer variability (mean difference ± SD) for the left ventricular outflow tract diameter was 0.05 ± 0.07 cm and 0.01 ± 0.03 cm respectively. There was minimal impact to the animal's daily activities. CONCLUSIONS: Transthoracic echocardiography was applicable and reproducible for the assessment of haemodynamics in baboons thus enabling translation of animal results to human studies.

Copulation patterns in captive hamadryas baboons: a quantitative analysis.

For primates, as for many other vertebrates, copulation which results in ejaculation is a prerequisite for reproduction. The probability of ejaculation is affected by various physiological and social factors, for example reproductive state of male and female and operational sex-ratio. In this paper, we present quantitative and qualitative data on patterns of sexual behaviour in a captive group of hamadryas baboons (Papio hamadryas), a species with a polygynous-monandric mating system. We observed more than 700 copulations and analysed factors that can affect the probability of ejaculation. Multilevel logistic regression analysis and Akaike's information criterion (AIC) model selection procedures revealed that the probability of successful copulation increased as the size of female sexual swellings increased, indicating increased probability of ovulation, and as the number of females per one-male unit (OMU) decreased. In contrast, occurrence of female copulation calls, sex of the copulation initiator, and previous male aggression toward females did not affect the probability of ejaculation. Synchrony of oestrus cycles also had no effect (most likely because the sample size was too small). We also observed 29 extra-group copulations by two non-adult males. Our results indicate that male hamadryas baboons copulated more successfully around the time of ovulation and that males in large OMUs with many females may be confronted by time or energy-allocation problems.

Female "dispersal" in hamadryas baboons: transfer among social units in a multilevel society.

Unlike most cercopithecines, hamadryas baboons (Papio hamadryas hamadryas) are characterized by female-biased dispersal. To clarify this pattern within the context of their hierarchical social system (comprising one-male units, clans, bands, and troops), we report here 7 years of data on female transfers among social units in wild hamadryas baboons in Ethiopia. Female tenure in one-male units (OMUs) ranged from 1 to 2,556 days (N = 208) and survival analysis revealed a median tenure length of 1,217 days (40 months). Changes in OMU membership consisted almost exclusively of takeovers by males, not voluntary transfer. Of 130 takeovers, 67% occurred within the band and 33% across bands, and, of the 22 takeovers for which we have clan membership data, 77% occurred within, not between, clans. These results reinforce the notion that hamadryas female dispersal is not analogous to sex-biased dispersal in other taxa, because (1) at least in Ethiopian populations, females do not disperse voluntarily but are transferred, often forcibly, by males; (2) only dispersal between bands will promote gene flow, whereas females are most often rearranged within bands; (3) hamadryas females undergo social dispersal but not usually locational dispersal; and (4) while male hamadryas are far more philopatric than females, they have been observed to disperse. It thus appears that the ancestral baboon pattern of female philopatry and male dispersal has evolved into a system in which neither sex is motivated to disperse, but females are forcibly transferred by males, leading to female-mediated gene flow, and males more rarely disperse to find females.

Not without a fair fight: failed abductions of females in wild hamadryas baboons.

In contrast to other papionin monkeys, hamadryas baboons are characterized by female-biased dispersal. Given that hamadryas females do not disperse voluntarily, one mechanism for female transfer between bands is thought to be abductions during aggressive intergroup conflict. To date, however, no successful abductions have been witnessed. We describe three abduction events at the Filoha field site in Ethiopia, two interband and one intraband, in which the abductors successfully separated a female from her leader male for several minutes or hours. In each case, the original leader male located the abductor and retrieved the female, even if it involved entering the social sphere of another band. These observations suggest that a hamadryas leader male will risk injury and loss of additional females in his attempt to retrieve a female from an abductor unless the abductor has openly challenged the leader for possession of his female and physically defeated him.

Morphological and physiological aspects of digestive processes in the graminivorous primate Theropithecus gelada-a preliminary study.

Hindgut fermentation has been suggested to contribute significantly to the digestive process in the gelada (Theropithecus gelada). We therefore hypothesized that in an in vitro fermentation test (Hohenheim gas test, using gas production as measure of microbial digestion) inoculum based on fresh gelada feces would degrade grass to a similar degree as zebra (Equus burchelli chapmani) feces and to a higher degree than that of hamadryas baboons (Papio hamadryas). Additionally, morphology of gelada tongue, salivary glands, stomach, and intestine were examined in this study. Gas production was measured between 4 and 96 hr using animal feces incubated with 200 mg of air-dry hay or mixed concentrate sample. For grass hay, 12-hr gas production was as follows: T. gelada (19.9 ml)>Papio (18.4 ml)>Equus (15.7 ml). After 24 hr, gas production changed: Papio (35.1 ml)>T. gelada (31.9 ml)>Equus (27.9 ml). At 96 hr, Papio was unexpectedly the most effective species with the highest gas production (53.1 ml)>zebra (51.2 ml)>gelada (49.4 ml). With a concentrate standard, 12-hr gas production was as follows: T. gelada (38.5 ml)>Equus (36.8 ml) = Papio (36.4 ml). At 24 hr, gas production differed: Papio (51.7 ml)>Equus (47.0 ml) = T. gelada (46.8 ml). At 96 hr, zebra was the most effective species with the highest gas production (63.9 ml)>Papio (60 ml) = T. gelada (59.9 ml). In conclusion, the results show that the microbial population present in gelada feces is able to ferment forage and concentrate substrates in vitro, although this fermentation did not occur with the expected effectiveness. Future studies should therefore focus also on the bacteria species involved.

Alternative routes to the leader male role in a multi-level society: follower vs. solitary male strategies and outcomes in hamadryas baboons.

The nested one-male units (OMUs) of the hamadryas baboon are part of a complex social system in which "leader" males achieve near exclusive mating access by forcibly herding females into permanent consortships. Within this multi-level social system (troops, bands, clans and OMUs) are two types of prereproductive males--the follower and solitary male--whose different trajectories converge on the leader role. Here we compare OMU formation strategies of followers, who associate with a particular OMU and may have social access to females, with those of solitary males, who move freely within the band and do not associate regularly with OMUs. Data were derived from 42 OMU formations (16 by followers and 26 by solitary males) occurring over 8 years in a hamadryas baboon band at the Filoha site in Ethiopia. "Initial units" (IUs) with sexually immature females (IU strategy) were formed by 44% of followers and 46% of solitary males. The remaining followers took over mature females when their leader was deposed (challenge strategy) or disappeared (opportunistic strategy), or via a seemingly peaceful transfer (inheritance strategy). Solitary males took over mature females from other clans and bands, but mainly from old, injured or vanished leaders within their clan (via both the challenge and opportunistic strategies). Former followers of an OMU were more successful at taking over females from those OMUs than any other category of male. Despite this advantage enjoyed by ex-follower leaders, ex-solitary leaders were equally capable of increasing their OMU size at a comparable rate in their first 2 years as a leader. These results demonstrate the potential for males to employ both multiple roles (follower vs. solitary male) and multiple routes (IU, inheritance, challenge, opportunistic) to acquire females and become a leader male in a mating system characterized by female defense polygyny in a competitive arena.

Differences between the normal vaginal bacterial community of baboons and that of humans.

Humans and baboons (Papio spp.) share considerable anatomical and physiological similarities in their reproductive tracts. Given the similarities, it is reasonable to expect that the normal vaginal microbial composition (microbiota) of baboons would be similar to that of humans. We have used a 16S rRNA phylogenetic approach to assess the composition of the baboon vaginal microbiota in a set of nine animals from a captive facility and six from the wild. Results show that although Gram-positive bacteria dominate in baboons as they do in humans, there are major differences between the vaginal microbiota of baboons and that of humans. In contrast to humans, the species of Gram-positive bacteria (Firmicutes) were taxa other than Lactobacillus species. In addition, some groups of Gram-negative bacteria that are not normally abundant in humans were found in the baboon samples. A further level of difference was also seen even within the same bacterial phylogenetic group, as baboon strains tended to be more phylogenetically distinct from human strains than human strains were with each other. Finally, results of our analysis suggests that co-evolution of microbes and their hosts cannot account for the major differences between the microbiota of baboons and that of humans because divergences between the major bacterial genera were too ancient to have occurred since primates evolved. Instead, the primate vaginal tracts appear to have acquired discrete subsets of bacteria from the vast diversity of bacteria available in the environment and established a community responsive to and compatible with host species physiology.