Tetsuro Matsuzawa

Japan Monkey Centre, Inuyama-chō, Gifu, Japan

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Publications (181)673.33 Total impact

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    ABSTRACT: African apes and humans share a genetic mutation that enables them to effectively metabolize ethanol. However, voluntary ethanol consumption in this evolutionary radiation is documented only in modern humans. Here, we report evidence of the long-term and recurrent ingestion of ethanol from the raffia palm (Raphia hookeri, Arecaceae) by wild chimpanzees (Pan troglodytes verus) at Bossou in Guinea, West Africa, from 1995 to 2012. Chimpanzees at Bossou ingest this alcoholic beverage, often in large quantities, despite an average presence of ethanol of 3.1% alcohol by volume (ABV) and up to 6.9% ABV. Local people tap raffia palms and the sap collects in
    Royal Society Open Science 06/2015; DOI:10.1098/rsos.150150
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    ABSTRACT: We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence, but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Trends in Ecology & Evolution 04/2015; 30(4). DOI:10.1016/j.tree.2015.02.002 · 15.35 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence , but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene. Understanding the human–ape interface A primary goal of many field studies of animal behaviour is to obtain data on behaviour in the ecological contexts in which that behaviour is presumed to have evolved. Hence, for many research questions, scientists rightly seek to study populations in places remote from dense human settlements and minimally disturbed by human activities. While many researchers have thereby focused little attention on human impacts, the scale of impacts at many sites is now substantial enough that they should be explicitly taken into account. Given that great apes (here also referred to as apes) reproduce slowly and require natural forest for food and shelter, impacts such as hunting and
    Trends in Ecology & Evolution 04/2015; · 15.35 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence , but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene. Understanding the human–ape interface A primary goal of many field studies of animal behaviour is to obtain data on behaviour in the ecological contexts in which that behaviour is presumed to have evolved. Hence, for many research questions, scientists rightly seek to study populations in places remote from dense human settlements and minimally disturbed by human activities. While many researchers have thereby focused little attention on human impacts, the scale of impacts at many sites is now substantial enough that they should be explicitly taken into account. Given that great apes (here also referred to as apes) reproduce slowly and require natural forest for food and shelter, impacts such as hunting and
    Trends in Ecology & Evolution 04/2015; · 15.35 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence , but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene. Understanding the human–ape interface A primary goal of many field studies of animal behaviour is to obtain data on behaviour in the ecological contexts in which that behaviour is presumed to have evolved. Hence, for many research questions, scientists rightly seek to study populations in places remote from dense human settlements and minimally disturbed by human activities. While many researchers have thereby focused little attention on human impacts, the scale of impacts at many sites is now substantial enough that they should be explicitly taken into account. Given that great apes (here also referred to as apes) reproduce slowly and require natural forest for food and shelter, impacts such as hunting and
    Trends in Ecology & Evolution 04/2015; · 15.35 Impact Factor
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    ABSTRACT: Stone tool use by wild chimpanzees of West Africa offers a unique opportunity to explore the evolutionary roots of technology during human evolution. However, detailed analyses of chimpanzee stone artifacts are still lacking, thus precluding a comparison with the earliest archaeological record. This paper presents the first systematic study of stone tools used by wild chimpanzees to crack open nuts in Bossou (Guinea-Conakry), and applies pioneering analytical techniques to such artifacts. Automatic morphometric GIS classification enabled to create maps of use wear over the stone tools (anvils, hammers, and hammers/ anvils), which were blind tested with GIS spatial analysis of damage patterns identified visually. Our analysis shows that chimpanzee stone tool use wear can be systematized and specific damage patterns discerned, allowing to discriminate between active and passive pounders in lithic assemblages. In summary, our results demonstrate the heuristic potential of combined suites of GIS techniques for the analysis of battered artifacts, and have enabled creating a referential framework of analysis in which wild chimpanzee battered tools can for the first time be directly compared to the early archaeological record.
    PLoS ONE 03/2015; 10(3). DOI:10.1371/journal.pone.0121613 · 3.53 Impact Factor
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    ABSTRACT: We discovered a lethal hemorrhagic syndrome arising from severe thrombocytopenia in Japanese macaques kept at the Primate Research Institute, Kyoto University. Extensive investigation identified that simian retrovirus type 4 (SRV-4) was the causative agent of the disease. SRV-4 had previously been isolated only from cynomolgus macaques in which it is usually asymptomatic. We consider that the SRV-4 crossed the so-called species barrier between cynomolgus and Japanese macaques, leading to extremely severe acute symptoms in the latter. Infectious agents that cross the species barrier occasionally amplify in virulence, which is not observed in the original hosts. In such cases, the new hosts are usually distantly related to the original hosts. However, Japanese macaques are closely related to cynomolgus macaques, and can even hybridize when given the opportunity. This lethal outbreak of a novel pathogen in Japanese macaques highlights the need to modify our expectations about virulence with regards crossing species barriers.
    Scientific Reports 03/2015; 5:8850. DOI:10.1038/srep08850 · 5.58 Impact Factor
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    American Journal of Primatology 01/2015; 77:319-329. · 2.14 Impact Factor
  • Yuko Hattori, Masaki Tomonaga, Tetsuro Matsuzawa
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    ABSTRACT: Humans tend to spontaneously align their movements in response to visual (e.g., swinging pendulum) and auditory rhythms (e.g., hearing music while walking). Particularly in the case of the response to auditory rhythms, neuroscientific research has indicated that motor resources are also recruited while perceiving an auditory rhythm (or regular pulse), suggesting a tight link between the auditory and motor systems in the human brain. However, the evolutionary origin of spontaneous responses to auditory rhythms is unclear. Here, we report that chimpanzees and humans show a similar distractor effect in perceiving isochronous rhythms during rhythmic movement. We used isochronous auditory rhythms as distractor stimuli during self-paced alternate tapping of two keys of an electronic keyboard by humans and chimpanzees. When the tempo was similar to their spontaneous motor tempo, tapping onset was influenced by intermittent entrainment to auditory rhythms. Although this effect itself is not an advanced rhythmic ability such as dancing or singing, our results suggest that, to some extent, the biological foundation for spontaneous responses to auditory rhythms was already deeply rooted in the common ancestor of chimpanzees and humans, 6 million years ago. This also suggests the possibility of a common attentional mechanism, as proposed by the dynamic attending theory, underlying the effect of perceiving external rhythms on motor movement.
    PLoS ONE 01/2015; 10(7):e0130682. DOI:10.1371/journal.pone.0130682 · 3.53 Impact Factor
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    ABSTRACT: The Great Ape Information Network has collated and archived information on captive chimpanzees within Japan since 2002. As of July 1st, 2014, a total of 323 chimpanzees were housed within 52 facilities across Japan, all registered in the Japanese Association of Zoos and Aquariums (JAZA) studbook. JAZA has recorded information on captive chimpanzees within Japan since the 1980s. However, for individuals unregistered and/or deceased prior to this period, JAZA holds scant information. There are very few surviving reports on living conditions and husbandry of such individuals, particularly for the years preceding the Second World War (WWII) (up to 1945). Here we present the first detailed history of captive chimpanzees in Japan before WWII, following a systematic investigation of disparate records. The first record of any live chimpanzee within Japan was a chimpanzee accompanying an Italian travelling circus in 1921. The history of resident captive chimpanzees in Japan began in 1927 when a chimpanzee, imported into Japan by a visitor, was exhibited in Osaka zoo. In the 1930s, many chimpanzee infants were imported to Japanese zoos until in 1941 imports were halted because of WWII. By the end of WWII, there was only one single chimpanzee still alive within Japan, “Bamboo”, housed in Nagoya. In 1951, importation of wild chimpanzees into Japan resumed. In total, we identified 28 individuals housed within Japan before 1945, none listed previously in the JAZA studbook. Of these 28 individuals: 6 entered Japan as pets and/or circus animals, 21 were imported to zoos, and one was stillborn in zoo. Of the 21 zoo-housed individuals, 7 died within one year and 9 of the remaining 14 were dead within 5 years of arriving in Japan. Four individuals are recorded to have lived 7-8 years. Only one male individual, the aforementioned “Bamboo”, lived notably longer, to about 14 years.
    Primate Research 01/2015; DOI:10.2354/psj.31.001
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    ABSTRACT: Induced pluripotent stem cells (iPSCs) are potentially valuable cell sources for disease models and future therapeutic applications; however, inefficient generation and the presence of integrated transgenes remain as problems limiting their current use. Here, we developed a new Sendai virus vector, TS12KOS, which has improved efficiency, does not integrate into the cellular DNA, and can be easily eliminated. TS12KOS carries KLF4, OCT3/4, and SOX2 in a single vector and can easily generate iPSCs from human blood cells. Using TS12KOS, we established iPSC lines from chimpanzee blood, and used DNA array analysis to show that the global gene-expression pattern of chimpanzee iPSCs is similar to those of human embryonic stem cell and iPSC lines. These results demonstrated that our new vector is useful for generating iPSCs from the blood cells of both human and chimpanzee. In addition, the chimpanzee iPSCs are expected to facilitate unique studies into human physiology and disease.
    PLoS ONE 12/2014; 9(12):e113052. DOI:10.1371/journal.pone.0113052 · 3.53 Impact Factor
  • 17th World Congress of Psychophysiology of the; 11/2014
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    ABSTRACT: We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked 80 km of transects and recces each month, and recorded 764 nests (mean group size = 2.23 nests) along with characteristics of vegetation structure and composition, topography, and seasonality. Population density estimated with two nest count methods ranged between 0.14 and 0.65 chimpanzee/km2. These values are lower than previous estimates, emphasizing the necessity of protecting remaining wild ape populations. Chimpanzees built nests in 108 tree species out of 437 identified, but 2.3% of total species comprised 52% of nests. Despite they preferred nesting in trees of 25–29 cm DBH and at a mean height of 8.02 m, we recorded an important proportion of terrestrial nests (8.2%) that may reflect a cultural trait of Nimba chimpanzees. A logistic model of nest presence formulated as a function of 12 habitat variables revealed preference for gallery and mountain forests rather than lowland forest, and old-growth forest rather than secondary forests. They nested more frequently in the study area during the dry season (December–April). The highest probability of observing nests was at 770 m altitude, particularly in steep locations (mean ground declivity = 15.54%). Several of the reported nest characteristics combined with the existence of two geographically separated clusters of nest, suggest that the study area constitutes the non-overlapping peripheral areas of two distinct communities. This nest-based study led us to findings on the behavioral ecology of Nimba chimpanzees, which constitute crucial knowledge to implement efficient and purpose-built conservation. Am. J. Primatol. © 2014 Wiley Periodicals, Inc.
    American Journal of Primatology 11/2014; 76(11). DOI:10.1002/ajp.22278 · 2.14 Impact Factor
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    ABSTRACT: To examine the evolutional origin of representational drawing, two experiments directly compared the drawing behavior of human children and chimpanzees. The first experiment observed free drawing after model presentation, using imitation task. From longitudinal observation of humans (N = 32, 11–31 months), the developmental process of drawing until the emergence of shape imitation was clarified. Adult chimpanzees showed the ability to trace a model, which was difficult for humans who had just started imitation. The second experiment, free drawing on incomplete facial stimuli, revealed the remarkable difference between two species. Humans (N = 57, 6–38 months) tend to complete the missing parts even with immature motor control, whereas chimpanzees never completed the missing parts and instead marked the existing parts or traced the outlines. Cognitive characteristics may affect the emergence of representational drawings.
    Child Development 11/2014; 85(6). DOI:10.1111/cdev.12319 · 4.92 Impact Factor
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    ABSTRACT: Chimpanzees are renowned for their use of foraging tools in harvesting social insects and some populations use tools to prey on aggressive army ants (Dorylus spp.). Tool use in army ant predation varies across chimpanzee study sites with differences in tool length, harvesting technique, and army ant species targeted. However, surprisingly little is known about the detailed ecology of army ant predation. We studied army ant predation by chimpanzees (Pan troglodytes verus) at the Seringbara study site in the Nimba Mountains, Guinea (West Africa), over 10 years (2003–2013). We investigated chimpanzee selectivity with regards to army ant prey species. We assessed the temporal variation in army ant-feeding and examined whether army ant predation was related to rainfall or ripe fruit availability. Moreover, we examined whether chimpanzees showed selectivity regarding plant species used for tool manufacture, as well as the relationship between tool species preference and tool collection distance. Lastly, we measured tool properties and investigated the use of tool sets and composite tools in army ant predation. Seringbara chimpanzees preyed on one army ant species (D. nigricans) more often than expected based on encounter rates, which may be explained by the overlap in altitudinal distribution between chimpanzees and D. nigricans. Army ant predation was not related to rainfall or fruit availability. Chimpanzees were selective in their choice of tool materials and collected their preferred tool species (Alchornea hirtella) from greater distances than they did other species. Lastly, Seringbara chimpanzees used both tool sets and composite tools (tree perch) in army ant predation. Tool types (dig vs. dip) differed in width and strength, but not length. Tool composites were found at 40% of ant-feeding sites. Our study sheds new light on the ecology of army ant predation and provides novel insights into chimpanzee selection of army ant prey and tool species. Am. J. Primatol. © 2014 Wiley Periodicals, Inc.
    American Journal of Primatology 10/2014; 77(3). DOI:10.1002/ajp.22347 · 2.14 Impact Factor
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    Mariska E Kret, Masaki Tomonaga, Tetsuro Matsuzawa
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    ABSTRACT: Group-living typically provides benefits to individual group members but also confers costs. To avoid incredulity and betrayal and allow trust and cooperation, individuals must understand the intentions and emotions of their group members. Humans attend to other's eyes and from gaze and pupil-size cues, infer information about the state of mind of the observed. In humans, pupil-size tends to mimic that of the observed. Here we tested whether pupil-mimicry exists in our closest relative, the chimpanzee (P. troglodytes). We conjectured that if pupil-mimicry has adaptive value, e.g. to promote swift communication of inner states and facilitate shared understanding and coordination, pupil-mimicry should emerge within but not across species. Pupillometry data was collected from human and chimpanzee subjects while they observed images of the eyes of both species with dilating/constricting pupils. Both species showed enhanced pupil-mimicry with members of their own species, with effects being strongest in humans and chimpanzee mothers. Pupil-mimicry may be deeply-rooted, but probably gained importance from the point in human evolution where the morphology of our eyes became more prominent. Humans' white sclera surrounding the iris, and the fine muscles around their eyes facilitate non-verbal communication via eye signals.
    PLoS ONE 08/2014; 9(8):e104886. DOI:10.1371/journal.pone.0104886 · 3.53 Impact Factor
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    ABSTRACT: Knowledge of the context and development of playful expressions in chimpanzees is limited because research has tended to focus on social play, on older subjects, and on the communicative signaling function of expressions. Here we explore the rate of playful facial and body expressions in solitary and social play, changes from 12-to 15-months of age, and the extent to which social partners match expressions, which may illuminate a route through which context influences expression. Naturalistic observations of seven chimpanzee infants (Pan troglodytes) were conducted at Chester Zoo, UK (n = 4), and Primate Research Institute, Japan (n = 3), and at two ages, 12 months and 15 months. No group or age differences were found in the rate of infant playful expressions. However, modalities of playful expression varied with type of play: in social play, the rate of play faces was high, whereas in solitary play, the rate of body expressions was high. Among the most frequent types of play, mild contact social play had the highest rates of play faces and multi-modal expressions (often play faces with hitting). Social partners matched both infant play faces and infant body expressions, but play faces were matched at a significantly higher rate that increased with age. Matched expression rates were highest when playing with peers despite infant expressiveness being highest when playing with older chimpanzees. Given that playful expressions emerge early in life and continue to occur in solitary contexts through the second year of life, we suggest that the play face and certain body behaviors are emotional expressions of joy, and that such expressions develop additional social functions through interactions with peers and older social partners.
    Frontiers in Psychology 07/2014; 5. DOI:10.3389/fpsyg.2014.00741 · 2.80 Impact Factor
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    ABSTRACT: The capacity for strategic thinking about the payoff-relevant actions of conspecifics is not well understood across species. We use game theory to make predictions about choices and temporal dynamics in three abstract competitive situations with chimpanzee participants. Frequencies of chimpanzee choices are extremely close to equilibrium (accurate-guessing) predictions, and shift as payoffs change, just as equilibrium theory predicts. The chimpanzee choices are also closer to the equilibrium prediction, and more responsive to past history and payoff changes, than two samples of human choices from experiments in which humans were also initially uninformed about opponent payoffs and could not communicate verbally. The results are consistent with a tentative interpretation of game theory as explaining evolved behavior, with the additional hypothesis that chimpanzees may retain or practice a specialized capacity to adjust strategy choice during competition to perform at least as well as, or better than, humans have.
    Scientific Reports 06/2014; 4:5182. DOI:10.1038/srep05182 · 5.58 Impact Factor
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    Primate Research 01/2014; 30(1):147-156. DOI:10.2354/psj.30.009

Publication Stats

4k Citations
673.33 Total Impact Points

Institutions

  • 2015
    • Japan Monkey Centre
      Inuyama-chō, Gifu, Japan
  • 1981–2015
    • Kyoto University
      • Primate Research Institute
      Kioto, Kyōto, Japan
  • 2012
    • University of Cambridge
      • Leverhulme Centre for Human Evolutionary Studies
      Cambridge, England, United Kingdom
  • 2010
    • Kyoto Prefectural University
      • Graduate School of Life and Environmental Sciences
      Kyoto, Kyoto-fu, Japan
    • University of Oxford
      • Department of Zoology
      Oxford, ENG, United Kingdom
  • 2006
    • University of Stirling
      • Department of Psychology
      Stirling, Scotland, United Kingdom
  • 1997
    • Kwansei Gakuin University
      Nishinomiya, Hyōgo, Japan
  • 1993
    • Oita Prefectural College of Arts and Culture
      Ōita, Ōita, Japan
  • 1992
    • Osaka University of Human Sciences
      Ōsaka, Ōsaka, Japan