Free-living Chimpanzees Research Articles

Age at first molar emergence in Pan troglodytes verus and variation in the timing of molar emergence among free-living chimpanzees

Age at lower first molar (M1) emergence is a commonly used proxy for inferring life-history scheduling in fossil primates, but its utility is dependent on knowing to what extent extant populations vary in this datum and how this variation correlates with the scheduling of life-history variables. Here, we address the first of these issues among extant chimpanzees. While age at M1 emergence has been documented in several live individuals from the Kanyawara population of Pan troglodytes schweinfurthii in Uganda, it has been estimated for only one individual of Pan troglodytes verus, based on a deceased animal from the Taï Forest in Côte d’Ivoire. To further explore interpopulation variation in this variable in chimpanzees, and using dental histology, we calculated ages at death for two wild-shot individuals of P. t. verus with erupting M1, both collected in Liberia during the mid-1950s, and estimated ages at M1 emergence from the ages at death. The overall range for these two individuals is ∼4.2–4.6 yr, compared with an age of ∼3.7 yr for the individual from the Taï Forest, and <2.5–3.3 yr for the several individuals of P. t. schweinfurthii. While the absolute range of ∼2 yr in these samples combined is little greater than in captive chimpanzees, the disparity between the samples of P. t. schweinfurthii and P. t. verus is striking, although it cannot be determined if this disparity represents a subspecies difference or simply population differences expressed in two different subspecies. While life-history data are unavailable for the population to which the Liberian chimpanzees belonged, the difference in M1 emergence ages between these individuals and those from Kanyawara still suggests caution when attempting even broad life-history inference in fossil apes and hominins based on age at M1 emergence.

Syndromic Surveillance of Respiratory Disease in Free-Living Chimpanzees.

Disease surveillance in wildlife is rapidly expanding in scope and methodology, emphasizing the need for formal evaluations of system performance. We examined a syndromic surveillance system for respiratory disease detection in Gombe National Park, Tanzania, from 2004 to 2012, with respect to data quality, disease trends, and respiratory disease detection. Data quality was assessed by examining community coverage, completeness, and consistency. The data were examined for baseline trends; signs of respiratory disease occurred at a mean frequency of less than 1 case per week, with most weeks containing zero observations of abnormalities. Seasonal and secular (i.e., over a period of years) trends in respiratory disease frequency were not identified. These baselines were used to develop algorithms for outbreak detection using both weekly counts and weekly prevalence thresholds and then compared retrospectively on the detection of 13 respiratory disease clusters from 2005 to 2012. Prospective application of outbreak detection algorithms to real-time syndromic data would be useful in triggering a rapid outbreak response, such as targeted diagnostic sampling, enhanced surveillance, or mitigation.

Kin, Daytime Associations, or Preferred Sleeping Sites? Factors Influencing Sleep Site Selection in Captive Chimpanzees (Pan troglodytes)

Chimpanzee nesting behaviours and the factors that may influence these behaviours are rarely studied in captive settings. In the present study, the daytime associations, sleeping site selections and nesting groups of 11 zoo-housed chimpanzees over a 29-day period were analysed. Neither daytime associations nor presence of kin influenced sleeping site selection in females. Daytime associations did influence sleeping arrangements in males. Nighttime spatial arrangements and individual preferences for specific sleeping areas were broadly comparable to nesting patterns reported in free-living chimpanzee communities. In the interests of captive ape welfare, we conclude that exhibits should incorporate multilevel nesting areas and a choice of several potential sleeping sites.

Dental development and life history in living African and Asian apes.

Life-history inference is an important aim of paleoprimatology, but life histories cannot be discerned directly from the fossil record. Among extant primates, the timing of many life-history attributes is correlated with the age at emergence of the first permanent molar (M1), which can therefore serve as a means to directly compare the life histories of fossil and extant species. To date, M1 emergence ages exist for only a small fraction of extant primate species and consist primarily of data from captive individuals, which may show accelerated dental eruption compared with free-living individuals. Data on M1 emergence ages in wild great apes exist for only a single chimpanzee individual, with data for gorillas and orangutans being anecdotal. This paucity of information limits our ability to make life-history inferences using the M1 emergence ages of extinct ape and hominin species. Here we report reliable ages at M1 emergence for the orangutan, Pongo pygmaeus (4.6 y), and the gorilla, Gorilla gorilla (3.8 y), obtained from the dental histology of wild-shot individuals in museum collections. These ages and the one reported age at M1 emergence in a free-living chimpanzee of approximately 4.0 y are highly concordant with the comparative life histories of these great apes. They are also consistent with the average age at M1 emergence in relation to the timing of life-history events in modern humans, thus confirming the utility of M1 emergence ages for life-history inference and providing a basis for making reliable life-history inferences for extinct apes and hominins.

Frequent foamy virus infection in free-living chimpanzees of the Taï National Park (Côte d'Ivoire)

Foamy viruses are frequently found in non-human primates and apes in captivity. However, data on simian foamy virus (SFV) infection in apes from the wild are limited. Necropsy specimens were collected from 14 West African chimpanzees (Pan troglodytes verus) from three communities in the Taï National Park, Côte d'Ivoire. PCR analysis revealed SFV-related int- and env-specific sequences in 12/14 chimpanzees. Two young chimpanzees were not infected. Plasma from 'PCR-positive' chimpanzees reacted against Pr71/74(gag) in Western blot analysis. Phylogenetic analysis demonstrated clustering of all analysed sequences with SFVcpz previously identified from the other P. troglodytes verus, although interestingly the sequences were diverse and no grouping according to a particular animal community was observed. The body compartments of two infected animals were examined and found to contain SFV sequences. Frequent SFV infections in chimpanzees from this area significantly increase the potential risk of zoonotic transmission to rural populations through direct contact, hunting and consumption of bush meat.

Aging and Fertility Patterns in Wild Chimpanzees Provide Insights into the Evolution of Menopause

Human menopause is remarkable in that reproductive senescence is markedly accelerated relative to somatic aging, leaving an extended postreproductive period for a large proportion of women. Functional explanations for this are debated, in part because comparative data from closely related species are inadequate. Existing studies of chimpanzees are based on very small samples and have not provided clear conclusions about the reproductive function of aging females. These studies have not examined whether reproductive senescence in chimpanzees exceeds the pace of general aging, as in humans, or occurs in parallel with declines in overall health, as in many other animals. In order to remedy these problems, we examined fertility and mortality patterns in six free-living chimpanzee populations. Chimpanzee and human birth rates show similar patterns of decline beginning in the fourth decade, suggesting that the physiology of reproductive senescence was relatively conserved in human evolution. However, in contrast to humans, chimpanzee fertility declines are consistent with declines in survivorship, and healthy females maintain high birth rates late into life. Thus, in contrast to recent claims, we find no evidence that menopause is a typical characteristic of chimpanzee life histories.

Timing and probability of ovulation in relation to sex skin swelling in wild West African chimpanzees, Pan troglodytes verus

Females of many catharrine primates show a periodic and often pronounced swelling of the perineum, the functional significance of which is unclear. Several hypotheses that exist to explain the function of this conspicuous trait are based on assumptions about the temporal relation between the period of maximum swelling and ovulation, and remain largely untested. We examined this relation in free-living chimpanzees of the Taı National Park, Côte d'Ivoire, and assessed the reliability of perineal swelling as an indicator of ovulation in this species. We used noninvasive urinary progestogen analysis of female reproductive status, together with observational data on swelling characteristics, to determine the variability of timing of ovulation within the maximum swelling phase in 36 cycles from 12 females. The period of maximum swelling was highly variable, lasting from 6 to 18 days. Although ovulation was virtually restricted to the second half of the period of maximum tumescence, its timing varied considerably in relation to both the onset and the end of the maximum tumescence phase. Probability of ovulation, however, was not random, but peaked on day 7 after the onset of the maximum swelling phase, and was almost 60% between days 7 and 9. Thus, in wild chimpanzees perineal swelling indicates the probability of ovulation, but does not provide sufficient information to deduce its exact timing. Given the temporal variability of ovulation relative to the last day of maximum tumescence, field workers should try to include hormonal analysis if information on timing of ovulation is required for interpretation of observational data. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.

Mortality rates among wild chimpanzees

In order to compare evolved human and chimpanzees' life histories we present a synthetic life table for free-living chimpanzees, derived from data collected in five study populations (Gombe, Taı̈, Kibale, Mahale, Bossou). The combined data from all populations represent 3711 chimpanzee years at risk and 278 deaths. Males show higher mortality than females and data suggest some inter-site variation in mortality. Despite this variation, however, wild chimpanzees generally have a life expectancy at birth of less than 15 years and mean adult lifespan (after sexual maturity) is only about 15 years. This is considerably lower survival than that reported for chimpanzees in zoos or captive breeding colonies, or that measured among modern human hunter-gatherers. The low mortality rate of human foragers relative to chimpanzees in the early adult years may partially explain why humans have evolved to senesce later than chimpanzees, and have a longer juvenile period.

Enamel hypoplasias as indicators of developmental stress in pongids and hominids

This paper reports the results from a study of enamel hypoplasia in the deciduous dentition of free-living Liberian chimpanzees (Pan troglodytes verus). The entire study collection includes 280 specimens (278 skulls plus two unassociated mandibles), of which 70 are young enough to retain some decidous teeth. Among the subsample of infants, the total frequency of hypoplasia summed over all teeth in any individual reaches 80%, being expressed in the form of pits rather than transverse lines. Hypoplasia of a linear form was common in the permanent dentition, attaining a frequency of 46.7% on maxillary central incisors and 69.7% on mandibular canines.

Growing Independence, Conflict and Learning in Mother-Infant Relations in Free-Ranging Chimpanzees

Growing Independence, Conflict and Learning in Mother-Infant Relations in Free-Ranging Chimpanzees

Models of primate development. Review of the behavioral development of free‐living chimpanzee babies and infants, by Frans X. Plooij. Norwood, NJ, Ablex Publishing Corporation, 1985, 207 pp, $27.50

American Journal of PrimatologyVolume 13, Issue 2 p. 209-211 Book Review Models of primate development. Review of the behavioral development of free-living chimpanzee babies and infants, by Frans X. Plooij. Norwood, NJ, Ablex Publishing Corporation, 1985, 207 pp, $27.50 Suzanne Chevalier-Skolnikoff, Suzanne Chevalier-Skolnikoff Human Interaction Laboratory, Department of Psychiatry, University of California, San FranciscoSearch for more papers by this author Suzanne Chevalier-Skolnikoff, Suzanne Chevalier-Skolnikoff Human Interaction Laboratory, Department of Psychiatry, University of California, San FranciscoSearch for more papers by this author First published: 1987 https://doi.org/10.1002/ajp.1350130213AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume13, Issue21987Pages 209-211 RelatedInformation

The behavioral development of free-living chimpanzee babies and infants

The behavioral development of free-living chimpanzee babies and infants

On Williams's Review of Evolutionary Biology and Human Social Behavior

American AnthropologistVolume 84, Issue 4 p. 896-897 Free Access On Williams's Review of Evolutionary Biology and Human Social Behavior WILLIAM IRONS, WILLIAM IRONS Northwestern UniversitySearch for more papers by this authorNAPOLEON A. CHAGNON, NAPOLEON A. CHAGNON Northwestern UniversitySearch for more papers by this author WILLIAM IRONS, WILLIAM IRONS Northwestern UniversitySearch for more papers by this authorNAPOLEON A. CHAGNON, NAPOLEON A. CHAGNON Northwestern UniversitySearch for more papers by this author First published: December 1982 https://doi.org/10.1525/aa.1982.84.4.02a00150AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References Cited Journal of Reproductive Fertility, Supplement 28: 43– 57. Tutin, C. E. G., and P. R. McGinnis 1981 Sexuality of the Chimpanzee in the Wild. In Reproductive Biology of the Great Apes. C. E. Graham, ed. pp. 239– 269. New York: Academic Press. van Lawick-Goodall, J. 1968 The Behaviour of Free-Living Chimpanzees in the Gombe Stream Reserve. Animal Behaviour Monograph 1: 161– 311. van Lawick-Goodall, J. 1970 Tool-using in Primates and other Vertebrates. In Advances in the Study of Behavior, Volume 3. D. S. Lehrman, R. A. Hinde, and E. Shaw, eds. pp. 195– 249. London: Academic Press. van Lawick-Goodall, J. 1973 Cultural Elements in a Chimpanzee Community. In Precultural Primate Behavior. E. W. Menzel, ed. pp. 144– 184. Basel, Switzerland: Karger. Washburn, S. L. 1960 Tools and Human Evolution. Scientific American 203(9): 63– 75. Waterfall, W. 1979 Form and Function: The Anatomists' View. Mosaic 10: 23– 29. Weiss, K. 1973 Demographic Models for Anthropology. Society for American Archaeology, Memoir 27. Wolpoff, M. H. 1973 Posterior Tooth Size, Body Size, and Diet in the South African Gracile Austral-opithecines. American Journal of Physical Anthropology 39: 375– 394. Wolpoff, M. H. 1976 Some Aspects of the Evolution of Early Hominid Sexual Dimorphism. Current Anthropology 17: 579– 606. Wolpoff, M. H. 1980 Paleoanthropology. New York: Knopf. Wolpoff, M. H. 1982 Ramapithecus and Human Origins: An Anthropologist's Perspective of Changing Interpretations. In New Interpretations of Ape and Human Ancestry. R. L. Ciochon and R. S. Corruccini, eds. New York: Plenum. Wrangham, R. W. 1979a On the Evolution of Ape Social Systems. Social Science Information 18: 335– 368. Wrangham, R. W. 1979b Sex Differences in Chimpanzee Dispersion. In The Great Apes. D. A. Hamburg and E. R. McCown, eds. pp. 481– 489. Menlo Park, Calif.: Benjamin/ Cummings. Volume84, Issue4December 1982Pages 896-897 ReferencesRelatedInformation

An observed birth in a free-living chimpanzee (Pan troglodytes schweinfurthii) in Gombe National Park, Tanzania

During 19 years of study of chimpanzees in the Gombe National Park only one birth has been observed; this is probably the first such observation for any chimpanzee in the natural habitat. The birth took place in a nest in a tall tree during the morning. Details were recorded by Tanzanian field staff from a neighbouring tree. Labour and parturition are described as well as the mother’s care of the infant immediately after birth. The mother consumed the placenta as she lay in another nest. Throughout the birth process the mother’s juvenile son remained close by and watched with apparent interest. Another mother and her offspring were present during the birth and an adult male approached the mother while she was feeding on the placenta. Their behaviour is described.

Infant killing and cannibalism in free-living chimpanzees.

Male chimpanzees at the Gombe National Park were twice seen to attack 'stranger' females and seize their infants. One infant was then killed and partially eaten: the other was 'rescued' and carried by three different males. Once several males were found eating a freshly killed 'stranger' infant. A similar event was observed in Uganda by Dr. Suzuki and Dr. Nishida reports an incident from the Mahali Mountains, Tanzania. A different kind of killing occurred at Gombe when a female and her daughter killed and ate three infants of other females of the same community during a 2-year period. There is evidence suggesting that other infants may have died in this way. The paper draws attention to puzzling aspects of infant killing and cannibalism in chimpanzees.

The recent rise to the alpha-rank in a population of free-living chimpanzees.

The recent rise of a high-ranking adult male chimpanzee to the alpha male position of the Gombe National Park's Kasakela chimpanzee community is reported. The male Figan is the fourth individual to assume this status in the wild chimpanzees' social hierarchy during Goodall's 16 year study in Tanzania. The paper describes the overthrow of the previous top-ranking male, and the manner in which Figan has maintained his new position after the take-over. Emphasis is placed upon his relationship with his elder male sibling, Faben, and the second highest-ranking male in the community, Evered.

Visualizing Interaction and Sequential Data in Animal Behaviour: Theory and Application of Cluster-Analysis Methods

Abstract The results of behavioural studies can be difficult to assimilate, often because such enormous quantities of data are involved, both as the studies are carried out and often in their final published form. This paper is concerned with data occurring in two-way tables which summarise, for example, the time each individual in a social group spends with every other individual, or the frequency with which every phrase in a bird's song follows every other one. We present some methods of cluster-analysis which help us to produce visual representations of such data. We describe how to build a single-link dendrogram (which is a way of representing a single-link cluster-analysis or SLCA) in Section 3 and a Maximum spanning-tree (MST) in Section 4. We also describe the properties of non-metric Multidimensional scaling (MDS) in Section 5, and B(2) cluster-analysis in section 6. Because methods of cluster-analysis often make fewer assumptions, we use them rather than factor analysis, principal-component analysis or canonical variate analysis. Section 8 compares the results of factor analyses with those of our cluster-analyses. The methods we describe are illustrated with reference to the times eleven free-living chimpanzees were seen together, analysed by SLCA in Section 3, MST in Section 4 and MDS in Section 5. Section 6 shows how B(2) analyses are used for the chimpanzee data, and Section 7 shows their application to data about sequences of phrases in a blackbird's song. In order to begin the cluster-analyses we present, our tables of raw data must be recast as tables of similarities. Section 2 introduces the art of constructing similarities, and Appendix I (1) shows how different kinds of similarity can be constructed from the same raw data. With reference to Appendix I (2b) and also to the data from BAERENDS et al. (1970) study of the incubation behaviour of herring gulls (Section 8), we emphasise that the act of constructing a particular kind of similarity commits one to a particular way of interpreting the data. Moreover, a method of constructing similarities can conceal differences of precision, Appendix I (3). Appendix I (2), examines the problems posed for cluster-analyses by asymmetric tables such as occur when elements precede other elements more often than vice versa, or when an individual in a social group grooms another for longer than vice versa. In Section 8, we illustrate how methods of cluster-analysis help us to interpret association data for 11 chimpanzees, and we examine the consistency of the chimpanzees' patterns of association through two consecutive 4-month periods. We then examine the association data of the whole community to which the 11 belong, and we use three consecutive analyses to show how the males in the community began to split into two sub-groups. We also compare he association data for three captive groups of rhesus monkeys; and we follow one group, comparing 12 consecutive monthly analyses to discover periods of change in that group's social organisation. We apply cluster-analyses to preceding-following tables from WIEPKEMA (1961) and BAERENDS et al. (1970), and we compare our interpretations of the original data with theirs. Finally, we show how cluster-analysis helps us to understand the songs of a blackbird, originally described by HALL-CRAGGS (1962). While we have emphasised the need to produce visual representations of our data, the need to evaluate them statistically remains, and Section 8-4 and Appendix II discuss the statistical methods for comparing dendrograms.

The Behaviour of Free-living Chimpanzees in the Gombe Stream Reserve

The Behaviour of Free-living Chimpanzees in the Gombe Stream Reserve

TOOL-USING AND AIMED THROWING IN A COMMUNITY OF FREE-LIVING CHIMPANZEES.

TOOL-USING AND AIMED THROWING IN A COMMUNITY OF FREE-LIVING CHIMPANZEES.