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ABSTRACT: Humans actively use behavioral synchrony such as dancing and singing when they intend to make affiliative relationships. Such advanced synchronous movement occurs even unconsciously when we hear rhythmically complex music. A foundation for this tendency may be an evolutionary adaptation for group living but evolutionary origins of human synchronous activity is unclear. Here we show the first evidence that a member of our closest living relatives, a chimpanzee, spontaneously synchronizes her movement with an auditory rhythm: After a training to tap illuminated keys on an electric keyboard, one chimpanzee spontaneously aligned her tapping with the sound when she heard an isochronous distractor sound. This result indicates that sensitivity to, and tendency toward synchronous movement with an auditory rhythm exist in chimpanzees, although humans may have expanded it to unique forms of auditory and visual communication during the course of human evolution.
Scientific Reports 03/2013; 3:1566.
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Tomoko Sakai,
Akichika Mikami,
Masaki Tomonaga,
Mie Matsui,
Juri Suzuki,
Yuzuru Hamada,
Masayuki Tanaka,
Takako Miyabe-Nishiwaki,
Haruyuki Makishima,
Masato Nakatsukasa, Tetsuro Matsuzawa
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Tomoko Sakai,
Mie Matsui,
Akichika Mikami,
Ludise Malkova,
Yuzuru Hamada,
Masaki Tomonaga,
Juri Suzuki,
Masayuki Tanaka,
Takako Miyabe-Nishiwaki,
Haruyuki Makishima,
Masato Nakatsukasa, Tetsuro Matsuzawa
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ABSTRACT: Developmental prolongation is thought to contribute to the remarkable brain enlargement observed in modern humans (Homo sapiens). However, the developmental trajectories of cerebral tissues have not been explored in chimpanzees (Pan troglodytes), even though they are our closest living relatives. To address this lack of information, the development of cerebral tissues was tracked in growing chimpanzees during infancy and the juvenile stage, using three-dimensional magnetic resonance imaging and compared with that of humans and rhesus macaques (Macaca mulatta). Overall, cerebral development in chimpanzees demonstrated less maturity and a more protracted course during prepuberty, as observed in humans but not in macaques. However, the rapid increase in cerebral total volume and proportional dynamic change in the cerebral tissue in humans during early infancy, when white matter volume increases dramatically, did not occur in chimpanzees. A dynamic reorganization of cerebral tissues of the brain during early infancy, driven mainly by enhancement of neuronal connectivity, is likely to have emerged in the human lineage after the split between humans and chimpanzees and to have promoted the increase in brain volume in humans. Our findings may lead to powerful insights into the ontogenetic mechanism underlying human brain enlargement.
Proceedings of the Royal Society B: Biological Sciences 01/2013; 280(1753):20122398. · 5.41 Impact Factor
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ABSTRACT: Describes a series of field experiments aimed at investigating aspects of emergence of cultural traditions in wild chimpanzee communities. The target behavior of the study reported here is nut cracking by chimpanzees at Bossou, Guinea, West Africa. Members of this community use a pair of stones as hammer and anvil to open oil-palm nuts. To examine aspects of such highly complex tool-using skills, the authors applied 2 distinct approaches. First, they carried out an extensive survey of neighboring communities and found that each community utilizes different species of nuts as the targets of cracking. Then, they introduced unfamiliar nuts to the Bossou chimpanzees and recorded their behavior toward these novel potential targets. The authors video-recorded all behavior during the repeated presentations of novel nuts, including individuals' initial responses and incidents of observing behavior, which helped ascertain how the cracking of nuts could spread among members of the community. The authors aimed to reveal processes of acquisition as well as their associated educational aspects in chimpanzees—in other words, the mechanisms involved in the transmission of knowledge and skills from one generation to the next. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
10/2012;
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ABSTRACT: Though many nonhuman primates possess a laryngeal sac, the great apes are unique in their great size. Though an enlarged sac
probably arose in their common ancestor, its functional adaptations remain a matter of debate. Its development in extant great
apes is likely to provide valuable information to clarify the issue. We used magnetic resonance imaging to examine the development
of the laryngeal sac in 3 living chimpanzees, age 4mo–5yr, and identified 2 distinct growth phases of the sac. A gradual
growth of the sac in early infancy results in a configuration so that it occupies the ventral region of the neck; many adult
nonhominoid primates having a sac show the configuration. The subsequent rapid expansion of the sac in late infancy causes
the final configuration in chimpanzees, wherein the sac expands into the pectoral, clavicular, and axillary regions. The latter
phase possibly arose at latest in the last common ancestor of extant great apes and contributed to the evolution of the enlarged
sac, despite the later evolutionary diversification in adult sac anatomy and growth. As many studies have advocated, the enlarged
sac probably plays a role in vocalization in adults. However, physiological modifications in the laryngeal region during infancy
are likely to provide valuable information to evaluate the functional adaptations of the enlarged sac in the great apes.
International Journal of Primatology 04/2012; 28(2):483-492. · 1.54 Impact Factor
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ABSTRACT: Nest-building is a great ape universal and arboreal nesting in chimpanzees and bonobos suggests that the common ancestor of Pan and Homo also nested in trees. It has been proposed that arboreal nest-building remained the prevailing pattern until Homo erectus, a fully terrestrial biped, emerged. We investigated the unusual occurrence of ground-nesting in chimpanzees (Pan troglodytes), which may inform on factors influencing the tree-to-ground sleep transition in the hominin lineage. We used a novel genetic approach to examine ground-nesting in unhabituated chimpanzees at Seringbara in the Nimba Mountains, Guinea. Previous research showed that ground-nesting at Seringbara was not ecologically determined. Here, we tested a possible mate-guarding function of ground-nesting by analyzing DNA from shed hairs collected from ground nests and tree nests found in close proximity. We examined whether or not ground-nesting was a group-level behavioral pattern and whether or not it occurred in more than one community. We used multiple genetic markers to identify sex and to examine variation in mitochondrial DNA control region (HV1, HV2) sequences. Ground-nesting was a male-biased behavior and males constructed more elaborate ("night") nests than simple ("day") nests on the ground. The mate-guarding hypothesis was not supported, as ground and associated tree nests were built either by maternally-related males or possibly by the same individuals. Ground-nesting was widespread and likely habitual in two communities. We suggest that terrestrial nest-building may have already occurred in arboreally-adapted early hominins before the emergence of H. erectus.
American Journal of Physical Anthropology 03/2012; 148(3):351-61. · 2.82 Impact Factor
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ABSTRACT: Why did our earliest hominin ancestors begin to walk bipedally as their main form of terrestrial travel? The lack of sufficient fossils and differing interpretations of existing ones leave unresolved the debate about what constitutes the earliest evidence of habitual bipedality. Compelling evidence shows that this shift coincided with climatic changes that reduced forested areas, probably forcing the earliest hominins to range in more open settings [1]. While environmental shifts may have prompted the origins of bipedality in the hominin clade, it remains unknown exactly which selective pressures led hominins to modify their postural repertoire to include a larger component of bipedality [2]. Here, we report new experimental results showing that wild chimpanzees walk bipedally more often and carry more items when transporting valuable, unpredictable resources to less-competitive places.
Current biology: CB 03/2012; 22(6):R180-1. · 10.99 Impact Factor
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ABSTRACT: Interactions between wildlife species are numerous and diverse, ranging from commensalism to predation. Information on cross-species interactions in anthropogenic habitats are rare but can serve to improve our understanding of animal behavioural and ecological flexibility in response to human-induced changes. Here we report direct observations of interactions between chimpanzees (Pan troglodytes verus) and wild and domesticated species in a forest-farm mosaic at Bossou, Guinea, recorded between 1997 and 2009. The low diversity and abundance of wildlife, in particu-lar typical chimpanzee prey species, are reflected in both the low interaction rates (one interaction per 400 observation hours) and the low number of species with which chimpanzees interacted (nine species, mostly mammals, but also birds and reptiles). Chimpanzees generally chose either to make direct physical contact with a species or not; interactions that involved direct contact lasted longer than noncontacts. Interactions with mammals showed the greatest diversity in nature and duration. Adults most often consumed a captured animal, while immatures most often engaged in play-ful behaviours with other species. Immatures also exhibited distinctive accompanying behaviours whereas adults rarely did so. Species-specific behaviours that depend on the age-class of the in-teractant are consistent with the idea that chimpanzees categorise different animals. We anticipate 300 Cross-species interactions that chimpanzee interactions with sympatric species inhabiting humanised habitats will change over time to include more domesticated species. Conservation management strategies should an-ticipate behavioural flexibility in response to changing landscapes.
Behaviour 01/2012; 149:299-324. · 1.57 Impact Factor
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Animal Behaviour 01/2012; · 3.49 Impact Factor
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ABSTRACT: Humans share implicit preferences for certain cross-sensory combinations; for example, they consistently associate higher-pitched sounds with lighter colors, smaller size, and spikier shapes. In the condition of synesthesia, people may experience such cross-modal correspondences to a perceptual degree (e.g., literally seeing sounds). So far, no study has addressed the question whether nonhuman animals share cross-modal correspondences as well. To establish the evolutionary origins of cross-modal mappings, we tested whether chimpanzees (Pan troglodytes) also associate higher pitch with higher luminance. Thirty-three humans and six chimpanzees were required to classify black and white squares according to their color while hearing irrelevant background sounds that were either high-pitched or low-pitched. Both species performed better when the background sound was congruent (high-pitched for white, low-pitched for black) than when it was incongruent (low-pitched for white, high-pitched for black). An inherent tendency to pair high pitch with high luminance hence evolved before the human lineage split from that of chimpanzees. Rather than being a culturally learned or a linguistic phenomenon, this mapping constitutes a basic feature of the primate sensory system.
Proceedings of the National Academy of Sciences 12/2011; 108(51):20661-5. · 9.68 Impact Factor
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ABSTRACT: The Balanophoraceae is a unique angiosperm family that fully parasitizes the roots of trees. Although the pollination systems of several genera in this family have been reported, little is known of their diversity. In the present study, we investigated the pollination biology of Thonningia sanguinea (Balanophoraceae) in the tropical rainforests of Guinea, West Africa. Female flies of the families Muscidae and Calliphoridae as well as Technomyrmex ants frequently visited flowers to consume nectar secreted from inflorescences. While feeding, their bodies attached to anthers or pollen grains. The most abundant flower-visiting fly, Morellia sp. (Muscidae), was observed laying eggs on T. sanguinea, and the larvae fed only on the vegetative tissue of decaying male inflorescences. Our findings provide a new candidate of pollination mutualism involving plants that provide brood sites for their pollinators.
Plant Species Biology 09/2011; 27(2):164-169. · 0.79 Impact Factor
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Tomoko Sakai,
Akichika Mikami,
Masaki Tomonaga,
Mie Matsui,
Juri Suzuki,
Yuzuru Hamada,
Masayuki Tanaka,
Takako Miyabe-Nishiwaki,
Haruyuki Makishima,
Masato Nakatsukasa, Tetsuro Matsuzawa
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ABSTRACT: A comparison of developmental patterns of white matter (WM) within the prefrontal region between humans and nonhuman primates is key to understanding human brain evolution. WM mediates complex cognitive processes and has reciprocal connections with posterior processing regions [1, 2]. Although the developmental pattern of prefrontal WM in macaques differs markedly from that in humans [3], this has not been explored in our closest evolutionary relative, the chimpanzee. The present longitudinal study of magnetic resonance imaging scans demonstrated that the prefrontal WM volume in chimpanzees was immature and had not reached the adult value during prepuberty, as observed in humans but not in macaques. However, the rate of prefrontal WM volume increase during infancy was slower in chimpanzees than in humans. These results suggest that a less mature and more protracted elaboration of neuronal connections in the prefrontal portion of the developing brain existed in the last common ancestor of chimpanzees and humans, and that this served to enhance the impact of postnatal experiences on neuronal connectivity. Furthermore, the rapid development of the human prefrontal WM during infancy may help the development of complex social interactions, as well as the acquisition of experience-dependent knowledge and skills to shape neuronal connectivity.
Current biology: CB 08/2011; 21(16):1397-402. · 10.99 Impact Factor
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ABSTRACT: Social animals have much to gain from observing and responding appropriately to the actions of their conspecific group members. This can in turn lead to the learning of novel behavior patterns (social learning) or to foraging, ranging, or social behavioral choices copied from fellow group members, which do not necessarily result in long-term learning, but at the time represent adaptive responses to environmental cues (public information use). In the current study, we developed a novel system for the study of public information use under fully automated conditions. We modified a classic single-subject laboratory paradigm--matching-to-sample (MTS)--and examined chimpanzees' ability to interpret and utilize cues provided by the behavior of a conspecific to solve the task. In Experiment 1, two subjects took turns on an identity MTS task, with one subject (the model) performing the first half of the trial and the other subject (the observer) completing the trial using the model's actions as discriminative cues. Both subjects performed above chance from the first session onwards. In Experiment 2, the subjects were tested on a symbolic version of the same MTS task, with one subject showing spontaneous transfer. Our study establishes a novel method for examining public information use within a highly controlled and automated setting.
Animal Cognition 06/2011; 14(6):893-902. · 3.09 Impact Factor
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ABSTRACT: 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.
American Journal of Primatology 03/2011; 73(3):226-32. · 2.22 Impact Factor
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ABSTRACT: Extensive research on human subjects has tried to investigate whether there is a correlation between cognitive performance and the menstrual cycle. Less is known about the relationship between the menstrual cycle and task performance in other cognitive animals. We test whether the secretion of a sex hormone [luteinizing hormone(LH)] influences the performance of cognitive tasks by a female chimpanzee (Pan troglodytes) who is part of a long-term cognition research program. We focus on two cognitive tasks: an "easy task," which consists of simple numerical ordering, and a "difficult task," which combines numerical ordering with memorizing the numerals' spatial location. Data on the performance of these cognitive tasks, urine samples, and sexual swelling over six menstrual cycles showed that the chimpanzee's performance accuracy decreased and that the intertrial interval was longer during the LH-surge of the menstrual cycle, but only for the performance of the difficult task. These performance attributes seem to reflect a decrease in attention or motivation during ovulation. In summary, the cognitive performance of a chimpanzee was disturbed by hormonal changes despite her long-term experience in the tasks.
Journal of Comparative Psychology 02/2011; 125(1):104-11. · 1.73 Impact Factor
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ABSTRACT: Snare injuries to chimpanzees (Pan troglodytes) have been reported at many study sites across Africa, and in some cases cause the death of the ensnared animal. However, very few snare injuries have been reported concerning the chimpanzees of Bossou, Guinea. The rarity of snare injuries in this study group warrants further consideration, given the exceptionally close proximity of the Bossou chimpanzees to human settlements and the widespread practice of snare hunting in the area. Herein we report a total of six observations of chimpanzees attempting to break and deactivate snares, successfully doing so on two of these occasions. We observed the behavior in 5 males, ranging in age from juveniles to adults. We argue that such active responses to snares must be contributing to the rarity of injuries in this group. Based on our observations, we suggest that the behavior has transmitted down the group. Our research team at Bossou continues to remove snares from the forest, but the threat of ensnarement still remains. We discuss potential ways to achieve a good balance between human subsistence activities and the conservation of chimpanzees at Bossou, which will increasingly be an area of great concern in the future.
Primates 01/2011; 52(1):1-5. · 1.40 Impact Factor
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01/2011: pages 123-130;
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ABSTRACT: The present chapter aims to report on a reforestation program known as the “Green Corridor Project,” which was initiated in
January 1997. This project aims to connect the chimpanzee habitat of Bossou to that of the Nimba Mountains. This project began
with a pilot study known as the “Petit Jardin Botanique.” This study aimed to evaluate the plant species that would best thrive
in a savanna environment. Over the years, the Green Corridor Project has involved the creation of tree nurseries, the introduction
of hexatubes to protect the young trees, and the planting of cuttings of Spondias cythera trees. The Green Corridor Project has promoted environmental awareness in the locality.
12/2010: pages 361-370;
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ABSTRACT: A small group of chimpanzees inhabits the forested hills surrounding the village of Bossou in southeastern Guinea, West Africa.
Over the years, cultural primatology has driven much of the research on this unique group of wild chimpanzees.
12/2010: pages 3-10;
