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Schrauf C.,University of Vienna | Call J.,Max Planck Institute for Evolutionary Anthropology | Fuwa K.,Hayashibara Biochemical Laboratories Inc. | Hirata S.,Hayashibara Biochemical Laboratories Inc.
PLoS ONE | Year: 2012

The extent to which tool-using animals take into account relevant task parameters is poorly understood. Nut cracking is one of the most complex forms of tool use, the choice of an adequate hammer being a critical aspect in success. Several properties make a hammer suitable for nut cracking, with weight being a key factor in determining the impact of a strike; in general, the greater the weight the fewer strikes required. This study experimentally investigated whether chimpanzees are able to encode the relevance of weight as a property of hammers to crack open nuts. By presenting chimpanzees with three hammers that differed solely in weight, we assessed their ability to relate the weight of the different tools with their effectiveness and thus select the most effective one(s). Our results show that chimpanzees use weight alone in selecting tools to crack open nuts and that experience clearly affects the subjects' attentiveness to the tool properties that are relevant for the task at hand. Chimpanzees can encode the requirements that a nut-cracking tool should meet (in terms of weight) to be effective. © 2012 Schrauf et al.

Hayashi S.,University of Bonn | Carpenter K.,Prehistoric Museum | Watabe M.,Hayashibara Biochemical Laboratories Inc. | McWhinney L.A.,Denver Museum Nature and Science
Palaeontology | Year: 2012

The dinosaur Stegosaurus is characterized by osteoderms of alternating plates and terminal paired spikes. Previous studies have described the histological features and possible functions of these osteoderms. However, ontogenetic changes are poorly documented. In this study, the ontogenetic changes of the osteoderms are examined using eight different ontogenetic skeletons (a juvenile, a subadult, a young adult, and five old adults based on the cortical histology of their body skeletons). The juvenile plate and subadult spike show thin cortex and thick cancellous bone. The young adult plates have an extensive vascular network, which is also seen in old adults. Old adult spikes are different from old adult plates in having a thick cortex and a large axial channel. The cortical histology, in both plates and spikes, show well-vascularized bone tissue consisting of dense mineralized fibres in young adult forms. In old adult forms, the bone tissues in the spikes become more compact and are extensively remodelled. This might contribute to the structural reinforcement of the spikes. The plates in old adult forms also show extensive remodelling and lines of arrested growth, but only limited signs of compaction. The timing for acquisition of features seen in old adults is different between plates (an extensive vascular network in the young adult) and spikes (a thick cortex with a large axial channel in old adults). The result suggests that the timing for plate and spike functions is different. The extensive vascular networks seen in large plates suggest their function is for display and/or thermoregulation. The thick cortical bone of spikes of old adults suggests that spikes acquire a weapon function for defence ontogenetically late. © The Palaeontological Association.

Myowa-Yamakoshi M.,Kyoto University | Myowa-Yamakoshi M.,Japan Science and Technology Agency | Scola C.,Aix - Marseille University | Hirata S.,Hayashibara Biochemical Laboratories Inc. | Hirata S.,Kyoto University
Nature Communications | Year: 2012

Humans comprehend the actions of others by making inferences about intentional mental states of another. However, little is known about how this capacity develops and whether this is shared with other animals. Here we show the ontogenetic and evolutionary foundations of this ability by comparing the eye movements of 8-and 12-month-old human infants, adults and chimpanzees as they watched videos presenting goal-directed and non-goal-directed actions by an actor. We find that chimpanzees anticipate action goals in the same way as do human adults. Humans and chimpanzees, however, scan goal-directed actions differently. Humans, particularly infants, refer to actors' faces significantly more than do chimpanzees. In human adults, attentional allocation to an actor's face changes as the goal-directed actions proceed. In the case of non-goal-directed actions, human adults attend less often to faces relative to goal-directed actions. These findings indicate that humans have a predisposition to observe goal-directed actions by integrating information from the actor. © 2012 Macmillan Publishers Limited. All rights reserved.

Kano F.,Kyoto University | Kano F.,Japan Society for the Promotion of Science | Hirata S.,Hayashibara Biochemical Laboratories Inc. | Call J.,Max Planck Institute for Evolutionary Anthropology | Tomonaga M.,Kyoto University
Vision Research | Year: 2011

Although an extensive body of literature exists on the cognitive underpinnings of gaze movements in macaques and humans, few studies have investigated this topic from a broader evolutionary perspective. This study used the gap-overlap paradigm to examine the timing of the gaze movements by four hominid species: humans, chimpanzees, gorillas, and orangutans. The saccade latency involved in shifting the gaze from central to peripheral stimuli was measured and compared under two conditions, gap and overlap. The central stimulus disappeared shortly before the onset of the peripheral stimulus under the gap condition, but it remained under the overlap condition. Although all species demonstrated similar saccade latencies under the gap condition, the species clearly differed from one another under the overlap condition, which may suggest their similar perceptual and motor mechanism of making a saccade on the one hand and their differential strategies for coping with the competition between two activities involving fixation and initiation of a saccade (i.e. central vs. peripheral visual stimuli) on the other hand. In particular, humans showed longer saccade latency under the overlap condition compared to the other great apes, which may reflect this species' unique means of visual processing. © 2011 Elsevier Ltd.

Saneyoshi M.,Hayashibara Biochemical Laboratories Inc. | Watabe M.,Hayashibara Biochemical Laboratories Inc. | Suzuki S.,Hayashibara Biochemical Laboratories Inc. | Tsogtbaatar K.,Mongolian Academy of science
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011

The formation processes of trace fossils - including shallow to deep pits, notches, borings (tunnels), and channels, particularly at the limb joints - observed on the surfaces of Velociraptor, Protoceratops, ankylosaurid, and Bagaceratops skeletons from Upper Cretaceous eolian deposits in the Gobi desert, Mongolia were investigated. The median diameters of these structures ranged from 5.25 to 7.68. mm. These structures were likely created by insects scavenging on dinosaur carcasses. This interpretation is corroborated by the presence of burrows of a size similar to the trace fossils observed on the dinosaur bone surfaces at the same locality. Broad borings (about 32. mm in diameter) created by small Mesozoic mammals have also been discovered on the ribs and scapulae of a Protoceratops skeleton. Dinosaur skeletons found at two localities, Tugrikin Shireh and Khermeen Tsav, and two formations, the Djadokhta Formation and Barun Goyot Formation, exhibited the same type of damage to the limb joints. The high frequency of trace fossils at the limb joints suggests that small animals targeted the collagen in the joint cartilage of dried dinosaur carcasses as a source of nitrogen, which was relatively scarce in the eolian environments of the Gobi desert during the Late Cretaceous. © 2011 Elsevier B.V.

Hirata S.,Hayashibara Biochemical Laboratories Inc. | Fuwa K.,Hayashibara Biochemical Laboratories Inc. | Sugama K.,Hayashibara Biochemical Laboratories Inc. | Kusunoki K.,Hayashibara Biochemical Laboratories Inc. | Takeshita H.,Hayashibara Biochemical Laboratories Inc.
Biology Letters | Year: 2011

Researchers have argued that the process of human birth is unique among primates and mammals in that the infant emerges with its face oriented in the opposite direction from its mother (occiput anterior) and head rotation occurs in the birth canal. However, this notion of human uniqueness has not been substantiated, because there are few comparative studies of birth in non-human primates. This paper reports the mechanism of birth in chimpanzees (Pan troglodytes) based on the first clear, close-up video recordings of three chimpanzee births in captivity. In all three cases, the foetus emerged with an occiput anterior orientation, and the head and body rotated after the head had emerged. Therefore, these characteristics are not uniquely human. Furthermore, in two of the three cases, the chimpanzee newborns landed on the ground without being guided from the birth canal by the mother. The fact that the human newborn emerges with an occiput anterior orientation has thus far been taken as evidence for the necessity of midwifery in modern humans, but this view also needs revision. Our observations raise the need to reconsider the evolutionary scenario of human birth. © 2011 The Royal Society.

Zamma K.,Hayashibara Biochemical Laboratories Inc.
Primates | Year: 2011

Grooming was observed in 11 wild chimpanzees (Pan troglodytes schweinfurthii) in Mahale, Tanzania, and the number of removal and stroke movements and grooming duration were recorded. Removal movements were more frequent during social grooming than during self-grooming. Chimpanzees used one or both hands for grooming, and grooming using both hands was more efficient for removing small objects. Due to physical constraints, self-grooming of the arms was almost always done using only one hand. The removal movement frequency during arm grooming was lower when self-grooming than when grooming another. They were more likely to use both hands during grooming another than during self-grooming, and fewer physical constraints during social grooming enabled a higher level of hygienic grooming. © 2011 Japan Monkey Centre and Springer.

Ohta H.,Hayashibara Biochemical Laboratories Inc. | Arai S.,Hayashibara Biochemical Laboratories Inc. | Akita K.,Hayashibara Biochemical Laboratories Inc. | Ohta T.,Hayashibara Biochemical Laboratories Inc. | Fukuda S.,Hayashibara Biochemical Laboratories Inc.
PLoS ONE | Year: 2011

Background: Neurotrophic factors may be future therapeutic agents for neurodegenerative disease. In the screening of biologically active molecules for neurotrophic potency, we found that a photosensitizing cyanine dye, NK-4, had remarkable neurotrophic activities and was a potent radical scavenger. Methodology/Principal Findings: In this study, we evaluated the effect of NK-4 on the protection of neurons against oxidative damage and investigated the associated intracellular signaling pathways. Subsequently, we evaluated the effect of NK-4 in an animal model of neurodegeneration. In vitro, NK-4 showed dose-dependent protection of PC12 cells from toxicity induced by oxidative stress caused by hydrogen peroxide (H 2O 2) or 6-hydroxydopamine (6-OHDA). Comparison of extracellular signal-regulated kinase signaling pathways between treatment with NK-4 and nerve growth factor (NGF) using K252a, an inhibitor of the NGF receptor TrkA, revealed that NK-4 activity occurs independently of NGF receptors. LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, blocked the protective effect of NK-4, and NK-4 caused activation of Akt/protein kinase B, a downstream effector of PI3K. These results suggest that the neuroprotective effects of NK-4 are mediated by the PI3K-Akt signaling pathway. NK-4 treatment also attenuated stress-induced activation of SAPK/JNK, which suggests that NK-4 activates a survival signaling pathway and inhibits stress-activated apoptotic pathways independently of the TrkA receptor in neuronal cells. In vivo, administration of NK-4 improved motor coordination in genetic ataxic hamsters, as assessed by rota-rod testing. Histological analysis showed that cerebellar atrophy was significantly attenuated by NK-4 treatment. Notably, the Purkinje cell count in the treated group was threefold higher than that in the vehicle group. Conclusions/Significance: These results suggest that NK-4 is a potential agent for therapy for neurodegenerative disorders based on the activation of survival signaling pathways. © 2011 Ohta et al.

Hirata S.,Hayashibara Biochemical Laboratories Inc. | Fuwa K.,Hayashibara Biochemical Laboratories Inc. | Sugama K.,Hayashibara Biochemical Laboratories Inc. | Kusunoki K.,Hayashibara Biochemical Laboratories Inc. | Fujita S.,Hayashibara Biochemical Laboratories Inc.
Animal Cognition | Year: 2010

This paper reports on the use of an eye-tracking technique to examine how chimpanzees look at facial photographs of conspecifics. Six chimpanzees viewed a sequence of pictures presented on a monitor while their eye movements were measured by an eye tracker. The pictures presented conspecific faces with open or closed eyes in an upright or inverted orientation in a frame. The results demonstrated that chimpanzees looked at the eyes, nose, and mouth more frequently than would be expected on the basis of random scanning of faces. More specifically, they looked at the eyes longer than they looked at the nose and mouth when photographs of upright faces with open eyes were presented, suggesting that particular attention to the eyes represents a spontaneous face-scanning strategy shared among monkeys, apes, and humans. In contrast to the results obtained for upright faces with open eyes, the viewing times for the eyes, nose, and mouth of inverted faces with open eyes did not differ from one another. The viewing times for the eyes, nose, and mouth of faces with closed eyes did not differ when faces with closed eyes were presented in either an upright or inverted orientation. These results suggest the possibility that open eyes play an important role in the configural processing of faces and that chimpanzees perceive and process open and closed eyes differently. © 2010 Springer-Verlag.

Ohta H.,Hayashibara Biochemical Laboratories Inc. | Arai S.,Hayashibara Biochemical Laboratories Inc. | Akita K.,Hayashibara Biochemical Laboratories Inc. | Ohta T.,Hayashibara Biochemical Laboratories Inc. | Fukuda S.,Hayashibara Biochemical Laboratories Inc.
PLoS ONE | Year: 2012

Beta-amyloid (Aβ) peptides are considered to play a major role in the pathogenesis of Alzheimer's disease (AD) and molecules that can prevent pathways of Aβ toxicity may be potential therapeutic agents for treatment of AD. We have previously reported that NK-4, a cyanine photosensitizing dye, displays neurotrophic and antioxidant activities. In this study, we report the effects of NK-4 on the toxicity of Aβ and on cognitive function and Aβ concentration in a transgenic mouse model of AD (Tg2576). In vitro, NK-4 effectively protected neuronal cells from toxicity induced by Aβ. In addition, it displayed profound inhibitory activities on Aβ fibril formation. In vivo, Tg2576 mice received an intraperitoneal injection at 100 or 500 μg/kg of NK-4 once a day, five times a week for 9 months. Administration of NK-4 to the mice attenuated impairment of recognition memory, associative memory, and learning ability, as assessed by a novel object recognition test, a passive avoidance test, and a water maze test, respectively. NK-4 decreased the brain Aβ concentration while increasing the plasma amyloid level in a dose-dependent manner. NK-4 also improved memory impairments of ICR mice induced by direct intracerebroventricular administration of Aβ. These lines of evidence suggest that NK-4 may affect multiple pathways of amyloid pathogenesis and could be useful for treatment of AD. © 2012 Ohta et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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