Behavior Of Baboons Research Articles

Genetic ancestry predicts male–female affiliation in a natural baboon hybrid zone

Opposite-sex social relationships are important predictors of fitness in many animals, including several group-living mammals. Consequently, understanding sources of variance in the tendency to form opposite-sex relationships is important for understanding social evolution. Genetic contributions are of particular interest due to their importance in long-term evolutionary change, but little is known about genetic effects on male-female relationships in social mammals, especially outside of the mating context. Here, we investigate the effects of genetic ancestry on male-female affiliative behaviour in a hybrid zone between the yellow baboon, Papio cynocephalus, and the anubis baboon, Papio anubis, in a population in which male-female social bonds are known predictors of life span. We place our analysis within the context of other social and demographic predictors of affiliative behaviour in baboons. Genetic ancestry was the most consistent predictor of opposite-sex affiliative behaviour we observed, with the exception of strong effects of dominance rank. Our results show that increased anubis genetic ancestry is associated with a subtle, but significantly higher, probability of opposite-sex affiliative behaviour, in both males and females. Additionally, pairs of anubis-like males and anubis-like females were the most likely to socially affiliate, resulting in moderate assortativity in grooming and proximity behaviour as a function of genetic ancestry. Our findings indicate that opposite-sex affiliative behaviour partially diverged during baboon evolution to differentiate yellow and anubis baboons, despite overall similarities in their social structures and mating systems. Furthermore, they suggest that affiliative behaviour may simultaneously promote and constrain baboon admixture, through additive and assortative effects of ancestry, respectively.

Sensitivity to geometric shape regularity in humans and baboons: A putative signature of human singularity

Among primates, humans are special in their ability to create and manipulate highly elaborate structures of language, mathematics, and music. Here we show that this sensitivity to abstract structure is already present in a much simpler domain: the visual perception of regular geometric shapes such as squares, rectangles, and parallelograms. We asked human subjects to detect an intruder shape among six quadrilaterals. Although the intruder was always defined by an identical amount of displacement of a single vertex, the results revealed a geometric regularity effect: detection was considerably easier when either the base shape or the intruder was a regular figure comprising right angles, parallelism, or symmetry rather than a more irregular shape. This effect was replicated in several tasks and in all human populations tested, including uneducated Himba adults and French kindergartners. Baboons, however, showed no such geometric regularity effect, even after extensive training. Baboon behavior was captured by convolutional neural networks (CNNs), but neither CNNs nor a variational autoencoder captured the human geometric regularity effect. However, a symbolic model, based on exact properties of Euclidean geometry, closely fitted human behavior. Our results indicate that the human propensity for symbolic abstraction permeates even elementary shape perception. They suggest a putative signature of human singularity and provide a challenge for nonsymbolic models of human shape perception.

Nonlethal management of baboons on the urban edge of a large metropole.

The transformation of natural land for agricultural and urban use has displaced baboons from large parts of their historical distribution. Abundant resources within transformed areas, however, continue to attract baboons back into these human-dominated areas resulting in chronic levels of conflict throughout much of Africa. In the city of Cape Town, chacma baboons (Papio ursinus) have been raiding human-derived foods for over 200 years. In the last 20 years, the management of this conflict has shifted from predominantly lethal to nonlethal methods. In this study, we assess the success of field rangers to deter baboons from urban areas and investigate whether such management affects the diet and activity patterns of baboons. We opportunistically sampled baboon behavior and movement when field rangers were temporarily absent from managed troops in 2008. We also compared the intensity of baboon management by comparing one troop on days when the field rangers aggressively herded the troop away from the urban edge versus passively monitored them in 2004/2005. Our results reveal that when field rangers were absent, the two troops spent 70% and 80% of their time within the urban edge compared to 3% and 19% when they were present. Both troops also consumed more human-derived foods when field rangers were absent. There was no significant change in the activity budget or daily distance traveled for either troop with and without field rangers. The intensity of herding did have an impact on baboon activity and high levels of herding significantly reduced time spent feeding and increased time spent traveling, socializing, and resting. Habitat use and dietary composition did not differ between high- and low-herding days. Our results suggest that field rangers are a successful nonlethal method for reducing spatial overlap between baboons and urban areas but that intensive, unsystematic herding of the troop does have measurable impacts on behavior and should be prevented.

Metagenomic analysis of dental calculus in ancient Egyptian baboons

Dental calculus, or mineralized plaque, represents a record of ancient biomolecules and food residues. Recently, ancient metagenomics made it possible to unlock the wealth of microbial and dietary information of dental calculus to reconstruct oral microbiomes and lifestyle of humans from the past. Although most studies have so far focused on ancient humans, dental calculus is known to form in a wide range of animals, potentially informing on how human-animal interactions changed the animals’ oral ecology. Here, we characterise the oral microbiome of six ancient Egyptian baboons held in captivity during the late Pharaonic era (9th–6th centuries BC) and of two historical baboons from a zoo via shotgun metagenomics. We demonstrate that these captive baboons possessed a distinctive oral microbiome when compared to ancient and modern humans, Neanderthals and a wild chimpanzee. These results may reflect the omnivorous dietary behaviour of baboons, even though health, food provisioning and other factors associated with human management, may have changed the baboons’ oral microbiome. We anticipate our study to be a starting point for more extensive studies on ancient animal oral microbiomes to examine the extent to which domestication and human management in the past affected the diet, health and lifestyle of target animals.

Abnormal behavior and associated risk factors in captive baboons (Papio hamadryas spp.).

Abnormal behavior, ranging from motor stereotypies to self-injurious behavior, has been documented in captive nonhuman primates, with risk factors including nursery rearing, single housing, and veterinary procedures. Much of this research has focused on macaque monkeys; less is known about the extent of and risk factors for abnormal behavior in baboons. Because abnormal behavior can be indicative of poor welfare, either past or present, the purpose of this study was to survey the presence of abnormal behavior in captive baboons and to identify potential risk factors for these behaviors with an aim of prevention. Subjects were 144 baboons (119 females, 25 males) aged 3-29 (median = 9.18) years temporarily singly housed for research or clinical reasons. A 15-min focal observation was conducted on each subject using the Noldus Observer® program. Abnormal behavior was observed in 26% of the subjects, with motor stereotypy (e.g., pace, rock, swing) being the most common. Motor stereotypy was negatively associated with age when first singly housed (P < 0.005) while self-directed behavior (e.g., hair pull, self-bite) was positively associated with the lifetime number of days singly housed (P < 0.05) and the average number of blood draws per year (P < 0.05). In addition, abnormal appetitive behavior was associated with being male (P < 0.05). Although the baboons in this study exhibited relatively low levels of abnormal behavior, the risk factors for these behaviors (e.g., social restriction, routine veterinary procedures, and sex) appear to remain consistent across primate species.

The behavioral pharmacology of anorexigenic drugs in nonhuman primates: 30 years of progress.

Comparatively few studies over the past 30 years have used pharmacological manipulations as a means of understanding processes underlying feeding behavior of nonhuman primates. In the 1970s and early 1980s, four laboratories provided data on the anorexigenic effects of a range of drugs on rhesus monkeys and baboons, and a fifth laboratory studied the effects of neuropeptides on feeding behavior of baboons. There were differences in the way anorexigenic drugs altered eating topography, and those that increased dopamine levels had greater abuse liability than those that increased serotonin levels. Studies in the 1980s and 1990s used foraging models and principles of behavioral economics to understand food-drug interactions. Experimenter-given anorexigenic drugs did not function as economic substitutes for food. Recent studies have examined the effects of a range of drugs on consumption of highly palatable food and model diet-induced obesity. Although some drugs, including stimulants, N-methyl-D-aspartate antagonists, and a cannabinoid antagonist increased the latency to standard food consumption, there was little evidence for a selective effect of any drug on highly palatable food consumption. Results obtained in nonhuman primates did not always confirm those observed in rodents. Future studies looking at sex differences and social factors may provide insight into factors related to human obesity.

Sociality and the evolution of intelligence

Two recently published studies provide important new data relevant to the evolution of human intelligence. Both studies of social behavior in baboons, Bergman et al. demonstrated that baboons use two criteria simultaneously to classify other troop members, and Silk et al. showed that highly social female baboons have higher reproductive success than less social females. Taken together, these studies provide strong evidence for the importance of social context in cognitive evolution.

Effect of solar eclipse on the behavior of a captive group of hamadryas baboons (Papio hamadryas)

AbstractTo date there have been no systematic studies on the effects of a solar eclipse on the behavior of nonhuman primates. However, some descriptive studies have reported an increase in inactivity levels and congregation of individuals during a solar eclipse. The aim of the present work was to carry out a systematic study of the effect of a solar eclipse on the behavior of baboons at an individual, gender, and one‐male unit (OMU) level. On 3 November 1994, Chile experienced a solar eclipse. A hamadryas baboon colony grouped in two OMUs at the Zoo of Santiago de Chile was observed 2 days before the solar eclipse (control situation), and during the eclipse for the same time period. Two observers simultaneously sampled the data. An all‐occurrence sampling method was used to collect data on threats and attacks made by adult individuals. Simultaneously, instantaneous samplings of 1 min each were used to record behavioral states of the two males and two females. In relation to the control situation, the effect of the solar eclipse on baboon behavior was a reduction in the rates of locomotion and threats, and an increase in the rates of inactivity and grooming, but not significantly so in all the focal individuals. Behavioral changes were more marked in males than in females, but did not differ between the two OMUs. Air temperature and humidity were similar in the two situations, and can therefore be discarded as causal effects on the behavioral changes of the baboons during the eclipse. Zoo Biol 22:299–303, 2003. © 2003 Wiley‐Sons, Inc.

Sex Differences in Captive Olive Baboon Behavior During the First Fourteen Days of Life

I discuss newborn baboon behavioral and proximity sex differences in a population of captive olive baboons (Papio anubis) living in a social group of >500 individuals. The data are based upon 20-min focal observations of 42 mother-newborn pairs (n = 27, n = 15) for infant-days 1–7 and 36 pairs (n = 23, n = 13) for infant-days 8–14 collected late-May through late-November 2001. I examined the first two weeks of infant life via behavioral, proximity, and approach-leave/contact analyses in order to determine whether behavioral sex differences exist during the first few days of life. I examine and analyze these 2 weeks independently due to different sample sizes. I used data from the total available sample population of 57 infants (n = 36, n = 21) to discuss birth, survivorship, and infant weight. Statistically significant age and/or age-sex interactions exist for all of the behavior and proximity measures during either infant-week 1 or 2. Moreover, there is a statistically significant difference in the birth sex ratio in the sample population but no significant difference in infant mortality by sex. There are also relative and significant differences in mothers' treatment of their newborn males and females. There are also some general tendencies for female newborns on average to suckle less and to explore more per focal observation than male infants do as they age. Conversely, male newborns average slightly more time per focal observation 1 m from the mother than do female infants. However, the observed differences may be influenced by maternal behavior in that mothers have higher rates of contact with their female than their male infants.

Climatic determinants of diet and foraging behaviour in baboons

Baboons (Papio spp.) are characterised by a large degree of variation in foraging behaviour and dietary composition. Previous analyses have suggested that much of this can be traced to differences in ecological conditions between sites. The proximate mechanism underlying these relationships is assumed to be mediated via the impact of climatic conditions on food availability, and ultimately the impact that this has on dietary composition. This paper examines these relationships more explicitly. Data from 15 baboon populations were used to assess the relationship between foraging variables and dietary composition. Only feeding time showed significant relationships with dietary composition, with percentage of time spent feeding decreasing with proportion of fruit in the diet, and increasing with the proportion of subterranean items. No relationships were found between diet composition and moving time or day journey length, although significant relationships were found between these variables and group size. The proportions of feeding time spent feeding on fruit, subterranean items and leaves were functions of the ecological conditions experienced by that population, although no relationships were found for the percentage of feeding time devoted to flowers or animal material. The relationships between the proportion feeding time spent on fruits, leaves and subterranean items and ecological variables could be best explained through understanding the way in which bush and tree level vegetation respond to the climatic environment and the impact this has on fruit availability. In this respect, temperature and seasonality are the key climatic parameters. This provides good support for the idea that the proximate mechanism underlying the relationship between foraging time and ecological variables is mediated via the impact of the climatic environment on vegetation structure and food availability. Similar factors have been proposed to explain much of the geographic variation in species diversity, suggesting that these relationships have far wider relevance and may account for much of the observed geographical variation in mammalian behaviour.

Effects of concurrent exposure to 60 Hz electric and magnetic fields on the social behavior of baboons

Effects of concurrent exposure to 60 Hz electric and magnetic fields on the social behavior of baboons

Effects of a 30 kV/m, 60 Hz electric field on the social behavior of baboons: a crossover experiment.

Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former control group was exposed to a 30 kV/m, 60 Hz electric field for 3 weeks. Only an extremely small, incidental magnetic field was generated by the exposure apparatus. We found that electric-field exposure again produced increases in the performance rates that index Passive Affinity, Tension, and Stereotypy. These findings, combined with results from our other electric-field experiments, indicate that exposure to strong electric fields, in the absence of associated magnetic fields, consistently produces effects that are expressed as increases in rates of performance of social behaviors in young adult male baboons.

Effects of exposure to 30 kV/m, 60‐Hz electric fields on the social behavior of baboons

We tested the hypothesis that exposure to a 30-kV/m, 60-Hz electric field produces significant change (stress) in the social behavior of adult male baboons (Papio cynocephalus anubis). One group of eight baboons was exposed to an electric field (12 hours per day, 7 days per week for 6 weeks) while a second group of eight baboons was maintained in a sham-exposure (control) condition. Exposed subjects and control subjects were compared over three, six-week experimental periods (pre-exposure, exposure, and post-exposure). Performance rates of six categories of social behaviors (passive affinity, active affinity, approach, tension, threat, and attack) and four categories of nonsocial behaviors (forage, manipulate, posture, and stereotypy) were used to compare the two groups. The results of our study indicate that 1) there were no significant differences between the two groups during the pre-exposure or post-exposure periods; 2) during the exposure period, experimental and control groups exhibited statistically significant differences in the mean performance rates of three behavior categories; 3) within-group comparisons across periods indicate that the experimentally exposed group exhibited statistically significant changes in passive affinity, tension, and stereotypy; and 4) changes in behavior performance among the exposed subjects reflect a stress response to the electric field.

Effects of exposure to a 60‐kV/m, 60‐Hz electric field on the social behavior of baboons

We found in a previously reported study that exposure to a 30-kV/m, 60-Hz electric field had significant effects on the social behavior of baboons. However, it was not established whether or not the effects were related specifically to the 30-kV/m intensity of the field. A new experiment was conducted to determine whether or not exposure to a 60-Hz electric field at 60 kV/m would produce like changes in the baboons' social behavior. We exposed one group of eight male baboons to an electric field 12 hours a day, 7 days a week, for 6 weeks. A second group of eight animals was maintained under sham-exposure (control) conditions. Rates of performing on each of six categories of social behavior and on four categories of nonsocial behavior were used as criteria for comparing exposed with unexposed subjects and for within-group comparisons during three six-week experimental periods: Pre-Exposure, Exposure, and Post-Exposure. The results indicate that (1) during the exposure period, exposed animals exhibited statistically significant differences from controls in means of performance rates based on several behavioral categories; (2) across all three periods, within-group comparisons revealed that behaviors of exposed baboons were significantly affected by exposure to the electric field; (3) changes in performance levels probably reflect a stress response to the electric field; and (4) the means of response rates of animals exposed at 60 kV/m were higher, but not double, those of animals exposed at 30 kV/m. As in the 30-kV/m experiment, animals exposed at 60 kV/m exhibited significant differences in performances of Passive Affinity, Tension, and Stereotypy. Mean rates of performing these categories were 122% (Passive Affinity), 48% (Tension), and 40% (Stereotypy) higher in the exposed group than in the control group during exposure to the 60-kV/m field.

Effects of cigarette nicotine content on smoking behavior of baboons

Human cigarette smokers modify the way in which they smoke cigarettes of differing nicotine content, apparently to maintain nicotine exposure at a preferred level. The effects of changing from moderate to high or low nicotine content cigarettes were examined in 11 baboons (superspecies Papio cynocephalus) trained to smoke cigarettes for water rewards. Relative to the moderate nicotine content cigarette, the animals took significantly ( p < .05) more puffs on the high nicotine content cigarette, and the puffs on the high nicotine cigarette were significantly larger in volume. The animals made the same number of puffs, relative to the moderate nicotine content cigarette, on the low nicotine content cigarette, but the volume of the puffs was significantly smaller. The cotinine output in urine varied significantly and was directly related to cigarette nicotine content; cotinine is the primary metabolite of nicotine. Baboons, like people, prefer high nicotine content cigarettes. Nonhuman primates also regulate nicotine exposure by modification of their puffing behavior. These results indicate that the nonhuman primate also can be used as a model for the investigation of the behavioral aspects of cigarette smoking.

Social play in differentially reared infant and juvenile baboons (Papio sp).

Effects of early experience and peer-group socialization on later play behavior of baboons (Papio sp) was assessed. The potential for development of sex differences in play behavior in the absence of sex-role models was of particular concern. Social play of nursery-reared baboons was contrasted with that of mother-reared conspecifics during late infancy (6-12 mo) and the late-juvenile period (36-42 mo). Males played more than did females and infants played more than did juveniles. There was no significant influence of early rearing conditions on play behavior despite effects on other behaviors. There were consistent sex differences in play behavior even for the individuals with no early access to sex-role models. This result is consistent with previous research indicating a strong hormonal basis of sex-differences in primate play behavior.

Restraint in primate chair may cause unusual behaviour in baboons; electrocorticographic correlates and corrective effects of diazepam

Whereas primates restrained in a chair may usually be considered ‘normal’, the behaviour of baboons in this position was considerably altered: their eyes were closed and they only slightly reacted to the approach of the experimenter (opening of the eyes), in contrast with their active behaviour when left free to move about in their cage. When the ECoG was recorded from certain cortical areas (particularly somatic area I), an unusual pattern developed during the restrained state: ‘drowsiness rhythms’, which typically appear in this area during transition from wakefulness to sleep, developed in long sustained sequences. Administration of diazepam, an anxiolytic drug, caused both the behaviour and the ECoG of the restrained animal to return to normal (i.e., attentive behaviour and ECoG characteristic of the true waking state). The prolonged drowsy-like ECoG and behaviour may therefore underline a reaction to the ‘stress’ conditions brought on by restraint.

Anti‐predator behaviour of baboons and impalas toward a cheetah

Anti‐predator behaviour of baboons and impalas toward a cheetah

Adaptations of crop‐raiding baboons in Kenya

AbstractA field study of baboon behavior as it relates to crop‐raiding was conducted on the Kenya Coast. The results proved useful for quantifying the distribution, movement, and other factors of their behavior. Such variables as troop organization, crop season, and the behavior of the farmers influence raiding behavior. Apparently diversionary activities of crop‐raiding baboons result from troop distribution along habitat margins between farms and forest and from baboon vigilance behavior.

A population survey of chacma baboon in the Northern Transvaal

To the farmers in mountainous areas in the Tranvaal, baboons are a menace which cause the death of lambs and the destruction of crops. The Nature Conservation Division thus embarked on a five-year field study to obtain data on the distribution, population density, ecology and social behaviour of baboons in the Transvaal. More than 300 baboon troops were located in the 7000 square mile study area in the Northern Transvaal. The population density varied between three and 18 per square mile in the different habitat types. Baboon troops were followed on foot for 74 days and it was found that the home range sizes varied between five and nine square miles. Capture cages were developed and control measures were applied according to a scheduled management plan. Most of the baboons were captured in heavy populated areas. Population changes were ascribed to dispersion and mortality.