Naruki Morimura

How to crack nuts: acquisition process in captive chimpanzees (Pan troglodytes) observing a model

Stone tool use for nut cracking consists of placing a hard-shelled nut onto a stone anvil and then cracking the shell open by pounding it with a stone hammer to get to the kernel. We investigated the acquisition of tool use for nut cracking in a group of captive chimpanzees to clarify what kind of understanding of the tools and actions will lead to the acquisition of this type of tool use in the presence of a skilled model. A human experimenter trained a male chimpanzee until he mastered the use of a hammer and anvil stone to crack open macadamia nuts. He was then put in a nut-cracking situation together with his group mates, who were naïve to this tool use; we did not have a control group without a model. The results showed that the process of acquisition could be broken down into several steps, including recognition of applying pressure to the nut, emergence of the use of a combination of three objects, emergence of the hitting action, using a tool for hitting, and hitting the nut. The chimpanzees recognized these different components separately and practiced them one after another. They gradually united these factors in their behavior leading to their first success. Their behavior did not clearly improve immediately after observing successful nut cracking by a peer, but observation of a skilled group member seemed to have a gradual, long-term influence on the acquisition of nut cracking by naïve chimpanzees.

Cortisol analysis of hair of captive chimpanzees (Pan troglodytes).

In addition to behavioral evaluations, stress assessments are also important for measuring animal welfare. Assessments of long-term stress are particularly important given that prolonged stress can affect physical health and reproduction. The use of hair cortisol as a marker of long-term stress has been increasing, but there has not yet been any report on the use of such methods with chimpanzees. Therefore, the purpose of this study was to establish and validate a methodology for analyzing hair cortisol in captive chimpanzees. In the first experiment, hair was removed from the arms of nine chimpanzees living in the Kumamoto Sanctuary (KS) and the regrown hair was sampled 3 months later. Fecal samples were collected periodically during the hair-growth period. The results showed that hair cortisol level was positively correlated with the rate of receiving aggression. Although the correlation between hair and fecal cortisol levels was not significant, the individual with the highest hair cortisol concentration also had the highest fecal cortisol concentration. These results suggest that hair cortisol may reflect long-term stress in chimpanzees. In the second experiment, we investigated the physiological factors affecting hair cortisol concentrations. We cut hair from the arms, sides, and backs of 25 chimpanzees living at the KS and the Primate Research Institute. The results revealed that cortisol varied based on source body part and hair whiteness. Therefore, we recommend that hair should always be collected from the same body part and that white hair should be avoided as much as possible.

The first chimpanzee sanctuary in Japan: an attempt to care for the "surplus" of biomedical research.

This article specifically examines several aspects of the human–captive chimpanzee bond and the effort to create the first chimpanzee sanctuary in Japan. We discuss our ethical responsibility for captive chimpanzees that have been used in biomedical research. On April 1, 2007, the Chimpanzee Sanctuary Uto (CSU) was established as the first sanctuary for retired laboratory chimpanzees in Japan. This initiative was the result of the continuous efforts by members of Support for African/Asian Great Apes (SAGA), and the Great Ape Information Network to provide a solution to the large chimpanzee colony held in biomedical facilities. However, the cessation of invasive biomedical studies using chimpanzees has created a new set of challenges because Japan lacks registration and laws banning invasive ape experiments and lacks a national policy for the life‐long care of retired laboratory chimpanzees. Therefore, CSU has initiated a relocation program in which 79 retired laboratory chimpanzees will be sent to domestic zoos and receive life‐long care. By the end of 2009, the number of chimpanzees living at CSU had decreased from 79 to 59 individuals. A nationwide network of care facilities and CSU to provide life‐long care of retired laboratory chimpanzees is growing across Japan. This will result in humane treatment of these research animals. Am. J. Primatol. 73:226–232, 2011.

Polymorphism of the Tryptophan Hydroxylase 2 (TPH2) Gene Is Associated with Chimpanzee Neuroticism

In the brain, serotonin production is controlled by tryptophan hydroxylase 2 (TPH2), a genotype. Previous studies found that mutations on the TPH2 locus in humans were associated with depression and studies of mice and studies of rhesus macaques have shown that the TPH2 locus was involved with aggressive behavior. We previously reported a functional single nucleotide polymorphism (SNP) in the form of an amino acid substitution, Q468R, in the chimpanzee TPH2 gene coding region. In the present study we tested whether this SNP was associated with neuroticism in captive and wild-born chimpanzees living in Japan and Guinea, respectively. Even after correcting for multiple tests (Bonferroni p = 0.05/6 = 0.008), Q468R was significantly related to higher neuroticism (β = 0.372, p = 0.005). This study is the first to identify a genotype linked to a personality trait in chimpanzees. In light of the prior studies on humans, mice, and rhesus macaques, these findings suggest that the relationship between neuroticism and TPH2 has deep phylogenetic roots.

Green passage plan (tree-planting project) and environmental education using documentary videos at Bossou: a progress report.

A group of chimpanzees at Bossou, Guinea, has been studied by Sugiyama and hi.s colleagues since 1976. Research has been fruitful, with results focusing on behavior, ecology, and a variety of tool-using skills unique to this group. · However, environmental conditions for the chimpanzees themselves are considerably less than favorable at Bossou. The area surrounding their habitat has been transformed into savanna . as a result of cultivation. More than a thousand Liberian refugees have been streamirig into the village of Bossou since 1990. Japanese researchers of the Primate Research Institute, Kyoto University, in cooperation with local villagers and supported by the Japanese government, the Guinean government and the Japanese embassy in Guinea, launched two projects aimed at protecting the chimpanzees.

Memory of movies by chimpanzees (Pan troglodytes).

How do animals remember what they see in daily life? The processes involved in remembering such visual information may be similar to those used in interpreting moving images on a monitor. In Experiment 1, 4 adult chimpanzees (Pan troglodytes) were required to discriminate between movies using a movie-to-movie matching-to-sample task. All chimpanzees demonstrated the ability to discriminate movies from the very 1st session onward. In Experiment 2, the ability to retain a movie was investigated through a matching-to-sample task using movie stills. To test which characteristics of movies are relevant to memory, the authors compared 2 conditions. In the continuous condition, the scenes comprising the movie progressed gradually, whereas in the discrete condition, the authors introduced a sudden change from one scene to another. Chimpanzees showed a recency effect only in the discrete condition, suggesting that composition and temporal order of scenes were used to remember the movies.

A note on enrichment for spontaneous tool use by chimpanzees (Pan troglodytes)

Abstract In the wild, decisions as to “when”, “where”, and “how” an animal acts are made based on the individual’s own choice; in contrast, the behaviour of wild animals in captivity may be under human control. To improve the physical and psychological well-being of captive animals, we should ensure that animals act on their own will, by ascertaining the voluntary nature of their behaviour. So far, most feeding enrichments permit an animal to use only one type of processing for each food item. This study was designed to permit voluntary tool-using behaviour by chimpanzees. Tube feeders from which chimpanzees could access orange juice using either tools or their hands were presented. Results showed that chimpanzees opted to use tools to access the juice in the feeders, even though the use of the mouth and the hands to obtain juice continued to occur intermittently until the end of the task. This finding demonstrated that when chimpanzees have the option to access juice through a variety of methods, they employ all available choices. It also supported the hypothesis that the behaviour of captive chimpanzees may come to resemble that of their wild counterparts as a function of behavioural freedom.

Effects of Relocation and Individual and Environmental Factors on the Long-Term Stress Levels in Captive Chimpanzees (Pan troglodytes): Monitoring Hair Cortisol and Behaviors.

Understanding the factors associated with the long-term stress levels of captive animals is important from the view of animal welfare. In this study, we investigated the effects of relocation in addition to individual and environmental factors related to social management on long-term stress level in group-living captive chimpanzees by examining behaviors and hair cortisol (HC). Specifically, we conducted two studies. The first compared changes in HC levels before and after the relocation of 8 chimpanzees (Study 1) and the second examined the relationship between individual and environmental factors and individual HC levels in 58 chimpanzees living in Kumamoto Sanctuary (KS), Kyoto University (Study 2). We hypothesized that relocation, social situation, sex, and early rearing conditions, would affect the HC levels of captive chimpanzees. We cut arm hair from chimpanzees and extracted and assayed cortisol with an enzyme immunoassay. Aggressive behaviors were recorded ad libitum by keepers using a daily behavior monitoring sheet developed for this study. The results of Study 1 indicate that HC levels increased during the first year after relocation to the new environment and then decreased during the second year. We observed individual differences in reactions to relocation and hypothesized that social factors may mediate these changes. In Study 2, we found that the standardized rate of receiving aggression, rearing history, sex, and group formation had a significant influence on mean HC levels. Relocation status was not a significant factor, but mean HC level was positively correlated with the rate of receiving aggression. Mean HC levels were higher in males than in females, and the association between aggressive interactions and HC levels differed by sex. These results suggest that, although relocation can affect long-term stress level, individuals’ experiences of aggression and sex may be more important contributors to long-term stress than relocation alone.

Analysis of hair cortisol levels in captive chimpanzees: Effect of various methods on cortisol stability and variability

Graphical abstract Summary of the experimental process. The items colored blue affected the results of the hair cortisol analysis in the present study. The stippled items were found to affect the results obtained in our previous study [1].

A case of maxillary sarcoma in a chimpanzee (Pan troglodytes).

Oral malignancy is rare in chimpanzees. A 34‐year‐old female chimpanzee (Pan troglodytes) at Kumamoto Sanctuary, Japan, had developed it. Treatment is technically difficult for chimpanzees while malignant neoplasm is seemingly rising in captive populations. Widespread expert discussion, guidelines for treatment, especially for great apes in terminal stages is urgently needed.