What Role Do Mothers Play in the Gestural Acquisition of Bonobos (Pan paniscus) and Chimpanzees (Pan troglodytes)?

Contemporary research hypothesizes that biological inheritance and ontogenetic factors shape the development of gestural communication in nonhuman great apes. However, little is known about the specific role that mothers play in the acquisition of their infants’ gestures. We observed 6 bonobo (Pan paniscus) and 4 chimpanzee (Pan troglodytes) mother–infant dyads and recorded their gesture types and frequency. We analyzed all behavioral contexts in which gestures occurred as well as the play context alone. Infants of both species were unlikely to share gestures with their mother or unrelated adult females. However, gestural sharing was prevalent within age groups. Within and across species, infant–infant and mother–mother groups were homogeneous regarding the types of gestures they shared, although there was individual variation in the frequency of gesture use. Our findings provide limited evidence that infants learned their gestures by imitating their mothers. Phylogenetic influences seem to be vital in gestural acquisition but, we suggest, repertoire development cannot be disentangled from individual social encounters during life.     

Are bonobos (Pan paniscus) really more bipedal than chimpanzees (Pan troglodytes)?

Of the living apes, the chimpanzee (Pan troglodytes) and bonobo (Pan paniscus) are often presented as possible models for the evolution of hominid bipedalism. Bipedality in matched pairs of captive bonobos and chimpanzees was analyzed to test hypotheses for the evolution of bipedalism, derived from a direct referential model. There was no overall species difference in rates of bipedal positional behavior, either postural or locomotory. The hominoid species differed in the function or use of bipedality, with bonobos showing more bipedality for carrying and vigilance, and chimpanzees showing more bipedality for display.     

Spatiotemporal Variation in Bonobo (Pan paniscus) Habitat Use in a Forest–Savanna Mosaic

International Journal of Primatology - Understanding the ecological and behavioral variation of primates is central to improving conservation strategies. Studies of chimpanzees (Pan troglodytes)...     

Tool-use by chimpanzees (Pan t. troglodytes) in the Lopé Reserve,Gabon

During a long-term study of chimpanzees in the Lopé Reserve, Gabon, tool-use to obtain insects or their products was observed four times and on 23 other occasions tools made and used by chimpanzees were recovered. Of 144 tools used to obtain insects, 142 were made from woody material. Tools varied in dimensions and in the degree of modification (bark stripping and fraying of ends) but those used to obtain different prey species were generally similar and resembled tools described from other chimpanzee populations in central Africa. Use of a leaf “sponge” to obtain water from a hole in the branch of a tree was observed once. Four tool-use patterns shown by other chimpanzee populations appeared to be absent at Lopé as no direct or indirect evidence of their existence was obtained in ten years.     

Survey of savanna chimpanzees (Pan troglodytes verus) in Southeastern Sénégal

A survey of the western subspecies of chimpanzee (Pan troglodytes verus) was conducted from 1 February to 9 April 2000 in Sénégal, West Africa, by the Miami Assirik Pan Project (MAPP). In addition to the Assirik area of the Parc National du Niokolo Koba (PNNK), areas south and east of the park were surveyed. Nests made by chimpanzees were used to estimate chimpanzee distribution and densities. Within the PNNK, chimpanzees were estimated to occur at an average of 0.13 individuals/km(2). Chimpanzee nests were recorded in nine of 10 locales surveyed outside of the PNNK, as well as within the park. Data on 994 nests made by chimpanzees were recorded outside the PNNK, while 736 nests were recorded inside the park. Nest density in areas surveyed outside the PNNK, such as Bandafassi, Tomboronkoto, and Segou, was comparable to that of Assirik in habitats where nests were concentrated (i.e., evergreen gallery forest). The purpose of MAPP was to initiate long-term research of chimpanzees in southeastern Sénégal, as a follow-up to the Stirling African Primate Project (SAPP) of the 1970s. We sought to replicate the standards set by the SAPP project, except when technological innovations allowed improvement in data collection procedures (e.g., the global positioning system (GPS)).     

Does space in the jaw influence the timing of molar crown initiation? A model using baboons (Papio anubis) and great apes (Pan troglodytes, Pan paniscus)

Radiographic and histological studies of baboon (Papio hamadryas, P. anubis) and chimpanzee (Pan troglodytes) permanent tooth development have found that periods of molar crown mineralization overlap markedly in chimpanzees but are staggered in baboons. Here we test the hypothesis that these intertaxon differences in molar initiation are primarily due to the space available in the mandibles of each species for these teeth. This study includes radiographic, linear measurement, and three-dimensional (3D) coordinate landmark data taken from baboon (Papio anubis n=51) and great ape (Pan paniscus n=43, P. troglodytes n=60) mandibles and permanent molars across a broad developmental range for each taxon. Unexpectedly, 3D multivariate statistical shape analysis of the molar crypt, crown, and root data shows that all three species trajectories of molar row shape change are indistinguishable from each other. Qualitative analysis of these 3D data reveals subtle and inconclusive intergeneric differences in the space maintained between adjacent molars during growth. The space distal to each newly initiated molar is slightly greater in the baboon. Bivariate analyses comparing molar row and mandibular corpus proportions in Papio and Pan fail to show clear or consistent taxonomic differences in the ratio of space afforded developing molars in the alveolar bone. Thus, there is a poor correlation between mandibular proportion and both intermolar spacing and 3D molar development pattern. Contrary to earlier studies, these results suggest that pattern of molar crown initiation and temporal overlap of adjacent mineralizing crowns is not significantly different between Papio and Pan. This may be due in part to the inclusion here of not only 3D molar crown data but also 3D molar crypt data. This study strongly refutes the hypothesis that space available in the mandible directly underlies different times of permanent molar crown initiation between Papio and Pan.     

Chaînes opératoires and resource-exploitation strategies in chimpanzee (Pan troglodytes) nut cracking

We apply archaeological methods to extend our knowledge of chimpanzee material culture. The cha?ne opératoire conceptual framework, as introduced by ethnography, established technology as a phased process. Prehistoric archaeology adopted this concept to elucidate technological variability in tool-making procedures, based on knowledge of tool functions or subsistence patterns. We focused on the detection of operational sequences by wild chimpanzees (Pan troglodytes verus) when nut cracking with lithic implements at the sites of Bossou and Diecké, Guinea, West Africa. Thus, while it has recently been claimed that chimpanzees leave behind recognizable assemblages of stone hammers that can be morphologically distinguished from Oldowan hammers, this is the first study to focus specifically on the existence of operational sequences during the utilization of stone tools by wild chimpanzees. By combining primatological and archaeological methods and examining ecological areas inhabited by different chimpanzee groups, we sought technological variability and identified variables influencing regional diversity in tool typology and technology. We compared three case studies: (1) Bossou-direct recording of experimental nut-cracking sessions; (2) Bossou- direct and indirect monitoring of nut-cracking sites in the wild; (3) Diecké-indirect monitoring of nut-cracking sites in the wild. Results suggest that chimpanzees perform sequences of repeated tool transport and nut cracking. Data show discrimination of tool functions based on tool features. We identified the most technologically complex tool for nut cracking, which was composed of four stones. We found regional diversity in chimpanzee stone assemblages. Raw-material type and tool mobility constrain technological development in human and nonhuman primates. Spatial analysis of tool distribution indicates a pattern of resource-exploitation strategy, revealing affinities with Oldowan.     

How Precisely Do Bonobos (Pan paniscus) Grasp Small Objects?

The general objective of this study was to compare the precise grasping behavior and intermanual differences in performance between three Pan paniscus and five Homo sapiens in grasping small objects. We compared the temporal pattern of two submovements of consecutive grasping cycles, the (visuomotor) reaching and the (sensorimotor) grasping. Both species were similarly successful in this task, they showed a behavioral right-hand preference and preferred specific types of grips. Bonobos required less time for reaching an object but a much longer time to grasp it than humans did. Thus, the species pursued different strategies. We assumed that this might be due to the different grip techniques. However, grip preferences did not serve a quicker intramanual performance but they pronounced differences between hands. Intermanual differences in timing were restricted to the reaching part and more strongly in bonobos than in humans. However, the right hand need not necessarily perform quicker. As in the case of humans, we assume that attentional cues were focused more on preparing a proper grip with the right hand than on a quick performance. However, strong intermanual differences in bonobos may indicate an overall stronger neuronal asymmetry in the motor organization of the finger musculature that prepare a proper grip than is true of humans.     

Chimpanzees’ constructional praxis (Pan paniscus, P. troglodytes)

This study investigated chimpanzees spontaneous spatial constructions with objects and especially their ability to repeat inter-object spatial relations, which is basic to understanding spatial relations at a higher level than perception or recognition. Subjects were six chimpanzees—four chimpanzees and two bonobos—aged 6–21 years, all raised in a human environment from an early age. Only minor species differences, but considerable individual differences were found. The effect of different object samples was assessed through a comparison with a previous study. A common overall chimpanzee pattern was also found. Chimpanzees repeated different types of inter-object spatial relations such as insertion (I), or vertical (V), or next-to (H) relations. However chimpanzees repeated I or V relations with more advanced procedures than when repeating H relations. Moreover, chimpanzees never repeated combined HV relations. Compared with children, chimpanzees showed a specific difficulty in repeating H relations. Repeating H relations is crucial for representing and understanding multiple reciprocal spatial relations between detached elements and for coordinating independent positions in space. Therefore, the chimpanzees difficulty indicates a fundamental difference in constructive space in comparison to humans. The findings are discussed in relation to issues of spatial cognition and tool use.     

Enteric protists in wild western chimpanzees (Pan troglodytes verus) and humans in Comoé National Park,Côte d'Ivoire

Primates - The western chimpanzee (Pan troglodytes verus), a subspecies of the common chimpanzee, is currently listed as Critically Endangered. Human-driven habitat loss and infectious diseases are...     

Male–Female Association Patterns Among Free-ranging Chimpanzees (Pan troglodytes schweinfurthii)

Although male–female relationships can offer a number of advantages such as protection or social support, they are poorly studied among primates compared to same-sex relationships. We used 12 yr of data from the Kanyawara chimpanzee community to compare three independent measures of association (party association, 5m association, and grooming) among all adult dyads. Party association exhibited by male–female dyads was of intermediate strength between strong male–male and weak female–female association. Male–female dyads were less likely to be within 5m of one another and to groom as male–male dyads, but equally likely to be within 5m and more likely to groom as female–female dyads. Variation in male–female association strength was not related to male rank but was affected by female ranging patterns and female reproductive states. Females with core areas in the center of the home range were more likely to be in parties with males but did not show higher spatial proximity or grooming indices compared to females ranging in the periphery. Party association and 5m indices were higher for dyads of males and estrous females compared to those with anestrous females. These results indicate that male–female dyads are likely to associate with one another more often than female–female dyads because of overlapping ranging patterns and short-term changes in female reproductive state. We conclude that male and female chimpanzees do not exhibit proximity and grooming patterns indicative of strong affiliative bonds. This study also highlights the importance of using multiple independent measures of bond strength in studies of primate social dynamics.     

Variability of antioxidant enzyme activity and isoenzyme profile in needles of Serbian spruce (Picea omorika (Panč.) Purkinye)

Variations were studied of the activity and isoenzyme patterns of soluble peroxidase, catalase, catechol oxidase and superoxide dismutase, in needles of the Balkan endemic conifer Serbian spruce, Picea omorika (Pan?.) Purkinye. The samples were collected from the natural habitat of the species, Mt. Tara. Seasonal changes were found to affect enzymatic activities and isoenzyme profiles. Total protein content was significantly lower in the summer than in other seasons. Several isoforms of peroxidase, catechol oxidase and superoxide dismutase (SOD), as well as two catalase isoenzymes were detected. The number of peroxidase isoenzymes was greatest during the vegetative season. Catalase and catechol oxidase peaked in summer and spring, respectively. Total SOD and Mn-SOD activities were significantly higher in the winter samples than the summer ones.     

Individual copulatory preference and the “strange female effect” in a captive group-living male chimpanzee (Pan troglodytes)

The common chimpanzee has been considered to be a promiscuous species, although transient consort relationships and male possessive behavior have been described byTutin (1975, 1979). A prolific adult male chimpanzee was housed with from four to seven adult female chimpanzees (depending on the females' maternal status) and copulations were recorded from August 7, 1978 until February 16, 1979, during morning feeding periods. Ten females composed the fluctuating available partners. Sixty-four observed copulations involved six females. One female was clearly preferred, including occasions when she was not maximally tumescent (e.g., completely detumescent, pregnant) and other available females were maximally tumescent. The remainder of the observed copulations, with one exception, involved females who had recently been reintroduced into the one-male breeding group. Such copulations took place on and continued temporarily after the day of reintroduction for two females, and after the resumption of menstrual cycling for two females who had been reintroduced while still lactating. Nonpreferred females were impregnated during the period of data collection, even though copulations with them were not observed. These data suggest that the male chimpanzee can form an individual mating preference regardless of the hormonal status of his available partners without lessening his reproductive success with nonpreferred females, but also tends toward maximization of his reproductive success by copulating with novel females.     

Morphological variation in adult chimpanzees (Pan troglodytes verus) of the Taï National Park, Côte d'Ivoire

Twenty five adult chimpanzee skeletons (Pan troglodytes verus) of known age and sex (15 females, 10 males) from a long‐term study site in Taï National Park, Cote d'Ivoire present new data on variation. These skeletons provide a rare opportunity to measure the cranium and postcranium from the same individuals. We compare measurements and indices of the Taï sample with those of relatively complete Pan troglodytes schweinfurthii skeletons from Gombe National Park, Tanzania. Measurements of Pan paniscus are included as an outside comparison. The Taï and Gombe samples are analyzed by sex; combined sex samples are compared between the two groups, and the two sexes to each other. Taï females and males do not differ in most long bone lengths or in pelvic dimensions, but do differ significantly in cranial capacity, facial measurements, clavicle length, scapular breadth, and femur length. Gombe females and males differ significantly in some facial measurements and in scapular breadth. In combined sex samples, Taï individuals have lower cranial capacity, longer palate and mandible, and greater dimensions in the trunk and limb lengths. Taï females account for most of the variation; males differ from each other only in greater length of humerus and femur. The Taï skeletons provide new data for assessing individual variation and sexual dimorphism within and between populations and species. The combination of cranial and postcranial data provides a clearer picture of chimpanzee intraspecific and interspecific variation than can be gained from either data set alone. Am J Phys Anthropol, 2008. © 2007 Wiley‐Liss, Inc.     

Versuche zur Symbol-Ereignis-Verknüpfung bei einer Zwergschimpansen (Pan paniscus Schwarz, 1929)

According toFiedler (1956) the pygmy chimpanzee is considered to be a separate species of the pongidae. Therefore, our investigations with a young female pygmy chimpanzee had two special aims. First, we hoped to collect some facts concerning the transferability of the experiments ofPremack (1971) within the great apes; he investigated the language skills of a common chimpanzee. Besides, we wanted to test the intellectual abilities of this littel known primate species. Pieces of wood, differing in color and shape, were used as symbols. At both sides, there was a magnet to hang them on an iron board. The subject had to choose between two or more signs out of three groups: food symbols, activity symbols and quantity symbols. The hanging up of one, later of two correlated symbols was followed by a special event for each of them. There is high concordance between the subject’s preferring of events and its preferring of symbols. The correlation-coefficient for food and food signs is as high as 0.95. Nearly without mistake is the subject’s use of the much/little signs in connection with the food symbols. The rate of error in general is between 10–20% and is in accordance to the corresponding results mentioned byPremack (1971). The way the subject learned the meaning of the symbols changed from slow to sudden comprehension. In general, these results provide further evidence of the high intelligence level of pygmy chimpanzees.      

Benzyladenine induction of buds and somatic embryogenesis in Picea omorika (Pančić) Purk.

Somatic embryogenesis and adventitious bud formation, initiated from shoot explants of Picea omorika is described. Benzyladenine (BA) as the only growth regulator, added to modified Von Arnold and Eriksson medium, induced formation of both adventitious buds and embryogenic tissue. Optimal BA concentration for bud induction was 4.5 M and further bud development and plantlet formation was achieved on growth regulator-free medium. The embryogenic tissue formation was induced when the explants were first grown on the medium with high BA content (22.5 M) and then transferred to medium without growth regulators. Subsequent proliferation of embryogenic tissue was accomplished by subculturing on medium containing 9 M 2,4-dichlorophenoxyacetic acid and 4.5 M BA, and further embryo development was achieved on medium with 12 M abscisic acid. Embryos cultured on growth regulator-free medium formed roots and rooted plantlets were successfully established in soil in the greenhouse.