Ontogeny of a social custom in wild chimpanzees: age changes in grooming hand-clasp at Mahale.

Among cultural behaviors of chimpanzees, the developmental processes of complex skills involved in tool use are relatively well known. However, few studies have examined the ontogeny of social customs that do not require complex skills. Thus, in this study, we describe the developmental process of the grooming hand-clasp (GHC), one of the well-known social customs of chimpanzees at Mahale.

Epidemiological study of zoonoses derived from humans in captive chimpanzees.

Emerging infectious diseases (EIDs) in wildlife are major threats both to human health and to biodiversity conservation. An estimated 71.8 % of zoonotic EID events are caused by pathogens in wildlife and the incidence of such diseases is increasing significantly in humans.

Parasitology of five primates in Mahale Mountains National Park, Tanzania.

Parasitological surveillance in primates has been performed using coprological observation and identification of specimens from chimpanzees (Pan troglodytes schweinfurthii) in Mahale Mountains National Park, Tanzania (Mahale). In this study, we conducted coprological surveillance to identify the fauna of parasite infection in five primate species in Mahale: red colobus (Procolobus badius tephrosceles), red-tailed monkeys (Cercopithecus ascanius schmidti), vervet monkeys (Cercopithecus aethiops pygerythrus), yellow baboons (Papio cynocephalus), and chimpanzees. Fecal samples were examined microscopically, and parasite identification was based on the morphology of cysts, eggs, larvae, and adult worms.

Genetic and 'cultural' similarity in wild chimpanzees.

The question of whether animals possess 'cultures' or 'traditions' continues to generate widespread theoretical and empirical interest. Studies of wild chimpanzees have featured prominently in this discussion, as the dominant approach used to identify culture in wild animals was first applied to them. This procedure, the 'method of exclusion,' begins by documenting behavioural differences between groups and then infers the existence of culture by eliminating ecological explanations for their occurrence.

Molecular identification of the causative agent of human strongyloidiasis acquired in Tanzania: dispersal and diversity of Strongyloides spp. and their hosts.

In order to identify the causative agent of imported strongyloidiasis found in a Japanese mammalogist, who participated in a field survey in Tanzania, the hyper-variable region IV (HVR-IV) of 18S ribosomal DNA and partial mitochondrial cytochrome c-oxidase subunit 1 gene (cox1) were analyzed and compared with Strongyloides fuelleborni collected from apes and monkeys of Africa and Japan, and S. stercoralis from humans, apes and dogs. The HVR-IV and cox1 of the patient's worms were identical to or only slightly differed from those of worms parasitic in Tanzanian chimpanzees and yellow baboons, demonstrating that the patient acquired the infection during her field survey in Tanzania.

Case report of helminths and lung mite infection in the red-tailed monkey, Cercopithecus ascanius schmidti, in Mahale Mountains National Park, Tanzania.

We documented the presence of gastrointestinal nematodes and lung mites in two red-tailed monkeys, Cercopithecus ascanius schmidti, in Mahale Mountains National Park, Tanzania. We detected lung mites, Pneumonyssus duttoni, in the trachea and bronchioles, and five species of nematodes, Oesophagostomum pachycephalum, Ternidens deminutus, Streptopharagus pigmentatus, Primasubulura distans, and Trichuris sp. in their gastrointestinal tracts.

Pirouettes: the rotational play of wild chimpanzees.

A pirouette is a locomotor-rotational movement in which a young chimpanzee spins around in a (mostly) quadruped posture while advancing forward in a straight line. We addressed whether this behavior evolved as a practice of general athletic ability or of sexual selection. The former hypothesis would predict no sex differences in skill or the developmental process, while the latter would predict the opposite.

Prevalence of muzzle-rubbing and hand-rubbing behavior in wild chimpanzees in Mahale Mountains National Park, Tanzania.

In 1998, four chimpanzees in the Mahale Mountains National Park, Tanzania, were observed wiping their mouths with non-detached leaves or stalks of grass, or rubbing their mouths with a tree trunk or branch, especially while eating lemons. The number of mouth-wiping/rubbing individuals increased to 18 in 1999. By 2005, 29 chimpanzees were documented wiping/rubbing their muzzles in this way.

Emergence, propagation or disappearance of novel behavioral patterns in the habituated chimpanzees of Mahale: a review.

Each local population of chimpanzees shows cultural variation, but little is known about how behavioral variations first emerge, and how often variants spread to other individuals and then become fixed as a local culture in chimpanzee society. Although field studies of chimpanzees are still too short to answer these questions definitively, it may stimulate further study in various sites to summarize the developments observed over the past 40 years at Mahale, Tanzania. Innovative patterns were operationally defined as new behavioral patterns performed by M group chimpanzees from 1981 onwards.

Descriptive epidemiology of fatal respiratory outbreaks and detection of a human-related metapneumovirus in wild chimpanzees (Pan troglodytes) at Mahale Mountains National Park, Western Tanzania.

Over the past several years, acute and fatal respiratory illnesses have occurred in the habituated group of wild chimpanzees at the Mahale Mountains National Park, Tanzania. Common respiratory viruses, such as measles and influenza, have been considered possible causative agents; however, neither of these viruses had been detected. During the fatal respiratory illnesses in 2003, 2005 and 2006, regular observations on affected individuals were recorded.

Relatedness in wild chimpanzees: influence of paternity, male philopatry, and demographic factors.

In chimpanzees (Pan troglodytes), high-ranking males are expected to have high reproductive success and females typically emigrate upon reaching maturity. Although high average relatedness among males in the same social groups has been assumed, previous reports have indicated that relatedness among males is not necessarily significantly higher than that among females. The paternity of 11 offspring and the relatedness of 50 individuals in the M group of chimpanzees at Mahale Mountains National Park, Tanzania, were investigated using DNA analyses.

Interspecies and intraspecies variations in the serotonin transporter gene intron 3 VNTR in nonhuman primates.

A variable number of tandem repeat (VNTR) polymorphism based on a 16 or 17-bp unit has been reported in the third intron of the human serotonin transporter gene (5-HTT). VNTRs have been shown to affect the transcriptional activity of genes, and VNTR polymorphisms possibly influence human personality and several psychoneurological disorders. To estimate the changes that occurred in the VNTRs during primate evolution, we amplified and sequenced the regions that corresponded to the human VNTRs in various primate species, including apes, Old World monkeys, and New World monkeys.

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.

Chimpanzee deaths at Mahale caused by a flu-like disease.

A flu-like disease spread among chimpanzees (Pan troglodytes schweinfurthii) of the M group at Mahale Mountains National Park, Tanzania, from June to July 2006. This epizootic or epidemic killed up to 12 chimpanzees. The obvious evidence of their deaths came from finding the bodies of three infants who had previously shown some symptoms of the disease.

Chimpanzee grouping patterns and food availability in Mahale Mountains National Park, Tanzania.

The aim of this study was to test for a correlation between party size and food (fruit) availability among the M group chimpanzees (Pan troglodytes) in the Mahale Mountains, Tanzania. Chimpanzee unit groups (or communities) show fission-fusion grouping patterns and form temporal parties. Fruit availability is assumed to be one of the important limiting factors in relation to the size of these parties.

Wild chimpanzee infant urine and saliva sampled noninvasively usable for DNA analyses.

In many genetic studies on the great apes, fecal or hair samples have been used as sources of DNA. However, feces and hairs are difficult to collect from chimpanzee infants under 3 years of age. As alternative DNA sources, we investigated the efficiency of collecting urine samples from infants compared with fecal samples, as well as the validity of the DNA extracted from urine and saliva samples of well-habituated M group chimpanzees (Pan troglodytes schweinfurthii) in the Mahale Mountains National Park, Tanzania.

Locomotor behavior and long bone morphology in individual free-ranging chimpanzees.

We combine structural limb data and behavioral data for free-ranging chimpanzees from Taï (Ivory Coast) and Mahale National Parks (Tanzania) to begin to consider the relationship between individual variation in locomotor activity and morphology. Femoral and humeral cross sections of ten individuals were acquired via computed tomography. Locomotor profiles of seven individuals were constructed from 3387 instantaneous time-point observations (87.

Tool-use for drinking water by immature chimpanzees of Mahale: prevalence of an unessential behavior.

Use of leaves or sticks for drinking water has only rarely been observed during long-term study of wild chimpanzees (Pan troglodytes schweinfurthii) at Mahale. Recently, however, we observed 42 episodes of tool-use for drinking water (73 tools and two cases of using "tool-sets") between 1999 and 2004. Interestingly, all of the performers were immature chimpanzees aged from 2 to 10 years.

Subtle behavioral variation in wild chimpanzees, with special reference to Imanishi's concept of kaluchua.

Here we consider the concept of kaluchua (a word adopted from the English "culture") in group-living animals developed by Imanishi in the 1950s. He distinguished it from bunka (the Japanese equivalent to the English "culture") because he thought that bunka had strong connotations of noble and intellectual human-like activities. Although he did not rigidly define kaluchua, his original concept of kaluchua was much broader than bunka and represented non-hereditary, acquired behavior that was acknowledged socially.

Leaf-pile pulling: an unusual play pattern in wild chimpanzees.

Play in nonhuman animals has generally been viewed as being uniform among study sites. No studies have examined whether there are local variations in play. In this work we report an apparently locality-specific form of play that is basically solo locomotor play, but also has aspects of object play and social play.

Extraordinarily low bone mineral density in an old female chimpanzee (Pan troglodytes schweinfurthii) from the Mahale Mountains National Park.

We examined bone mineral density (BMD) of the femoral neck and lumbar vertebrae of four chimpanzee skeletons from Mahale Mountains National Park, Tanzania, and four captive ones, with a dual energy X-ray absorptiometer. The BMD of Wansombo, an old female chimpanzee from Mahale, was remarkably lower than the mean of the other six younger adult female chimpanzees and categorized as osteoporosis. Posture, locomotion, and trunk-sacral anatomy of chimpanzees may have prevented fractures in Wansombo, whose BMD was below human osteoporosis criteria.

Demography, female life history, and reproductive profiles among the chimpanzees of Mahale.

Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48%), followed by senescence (24%) and within-species aggression (16%).

Social scratch: Another custom in wild chimpanzees?

Chimpanzees (Pan troglodytes schweinfurthii) in the Mahale Mountains National Park, Tanzania, scratch other individual's bodies while they groom them. This behavioral pattern of "social scratch" is another example of locality-specific social behavior, or custom, as it is not found in the Gombe National Park, Tanzania, about 150 km north of Mahale, nor has it been reported from any other sites of chimpanzee study. Frequency of social scratch was correlated with frequency of social grooming, but not with frequency of self-scratch.