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2.
Biol Lett ; 15(7): 20190209, 2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31311488

RESUMO

The communicative function of primates' self-directed behaviours like scratching has gained increasing attention in recent years, but their intentional use is still debated. Here, we addressed this issue by exploring the communicative function of 'loud scratches' in wild Sumatran orangutans. Building on previous studies in chimpanzees, we examined the prediction that audio-visual loud scratches are used communicatively in mother-infant travel coordination. Specifically, we examined whether individual, social and scratch features affected the use of pre-move scratches, markers of intentional signal use and approach responses. We analysed a total of 1457 scratching bouts, produced by 17 individuals (including four mothers and their dependent offspring) observed during 305 h of focal follows. Overall, we found that scratching bouts preceded departure mainly when these were produced by mothers and showed features of exaggeration. If the scratching individual was a mother, associates were more likely to be visually attentive during pre-move scratches than in other contexts. Approach or follow responses to scratches by individuals in association were predicted by context, the relationship with the scratcher (i.e. offspring) and the associate's attentional state. We conclude that orangutan mothers use loud scratches as communicative strategies to coordinate joint travel with their infants.


Assuntos
Pongo abelii , Animais , Feminino , Gestos , Humanos , Mães , Pan troglodytes , Pongo pygmaeus
3.
Am J Primatol ; 81(6): e22976, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31094019

RESUMO

Olfaction is important across the animal kingdom for transferring information on, for example, species, sex, group membership, or reproductive parameters. Its relevance has been established in primates including humans, yet research on great apes still is fragmentary. Observational evidence indicates that great apes use their sense of smell in various contexts, but the information content of their body odor has not been analyzed. Our aim was therefore to compare the chemical composition of body odor in great ape species, namely Sumatran orangutans (Pongo abelii (Lesson, 1827), one adult male, five adult females, four nonadults), Western lowland gorillas (Gorilla gorilla gorilla (Savage, 1847), one adult male, two adult females, one nonadult), common chimpanzees (Pan troglodytes (Blumenbach, 1775), four adult males, nine adult females, four nonadults), and bonobos (Pan paniscus (Schwarz, 1929), two adult males, four adult females, two nonadults). We collected 195 samples (five per individual) of 39 captive individuals using cotton swabs and analyzed them using gas chromatography mass spectrometry. We compared the sample richness and intensity, similarity of chemical composition, and relative abundance of compounds. Results show that species, age, and potentially sex have an impact on the variance between odor profiles. Richness and intensity varied significantly between species (gorillas having the highest, bonobos the lowest richness and intensity), and with age (both increasing with age). Richness and intensity did not vary between sexes. Odor samples of the same species were more similar to each other than samples of different species. Among all compounds identified some were associated with age (N = 7), sex (N = 6), and species-related (N = 37) variance. Our study contributes to the basic understanding of olfactory communication in hominids by showing that the chemical composition of body odor varies across species and individuals, containing potentially important information for social communication.


Assuntos
Gorilla gorilla/fisiologia , Odorantes/análise , Pan paniscus/fisiologia , Pan troglodytes/fisiologia , Pongo abelii/fisiologia , Fatores Etários , Animais , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Fatores Sexuais
4.
Am J Primatol ; 81(1): e22945, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30604887

RESUMO

The diversity of great ape diets requires behavioral flexibility. Consequently, the exploration of potentially novel food sources is supposedly beneficial, but simultaneously, apes show high neophobia to prevent harmful and poisonous food intake. Social information, such as presence of group members or observations of non-naïve, experienced individuals have been demonstrated to affect the acceptance of novel food items in primates. Sociality may have evolutionary effects on the response of apes to novel foods. Here we assess the social information hypothesis, which predicts that selection favors higher neophobia in species where social information is abundant. We report the results from 134 great apes housed in multiple facilities from four closely related species that naturally differ in their degree of sociality: Pongo pygmaeus, Pongo abelii, Pan troglodytes and Pan paniscus. We examined individuals' reactions to novel foods when alone, which enabled us to detect any inherent differences and revealed significant distinctions between species. Chimpanzees and bonobos, that are naturally exposed to higher amounts of social information, were less likely to consume novel foods alone (showed higher neophobia) than the two more solitary orangutan species. Chimpanzees were especially cautious and showed higher explorative behaviors before tasting novel food than other species. Age influenced neophobia as younger individuals of all species took longer to taste novel foods than adults did.


Assuntos
Comportamento Alimentar/psicologia , Pan paniscus/psicologia , Pan troglodytes/psicologia , Pongo abelii/psicologia , Pongo pygmaeus/psicologia , Fatores Etários , Animais , Feminino , Preferências Alimentares/psicologia , Masculino , Comportamento Social
5.
J Med Primatol ; 48(2): 133-136, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30443913

RESUMO

An orangutan (Pongo abelii) presented with chronic respiratory problems. Cytological evaluation of the bronchoalveolar lavage fluids revealed macrophages with well-circumscribed intracytoplasmic clear vacuoles and lipid droplets in the background, confirmed by Oil Red O staining. The findings were indicative of lipoid pneumonia. This is the first report of lipoid pneumonia in an orangutan.


Assuntos
Doenças dos Símios Antropoides/diagnóstico , Pneumonia Lipoide/veterinária , Animais , Doenças dos Símios Antropoides/diagnóstico por imagem , Evolução Fatal , Feminino , Pneumonia Lipoide/diagnóstico , Pneumonia Lipoide/diagnóstico por imagem , Pongo abelii , Tomografia Computadorizada por Raios X
6.
J Med Primatol ; 48(1): 65-67, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30307044

RESUMO

A Delorme's procedure perineal surgical repair was performed in a wild adult male Sumatran orangutan (Pongo abelii) with a chronic persistent rectal prolapse that had been unsuccessfully treated by 6 previous surgeries. The rectal prolapse did not recur, and the orangutan was successfully released to the wild, 6 weeks later.


Assuntos
Doenças dos Símios Antropoides/cirurgia , Pongo abelii , Prolapso Retal/veterinária , Animais , Masculino , Prolapso Retal/cirurgia , Resultado do Tratamento
7.
J Hum Evol ; 125: 38-49, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30502896

RESUMO

Orangutans (Pongo spp.) are reported to have extremely slow life histories, including the longest average interbirth intervals of all mammals. Such slow life history can be viable only when unavoidable mortality is kept low. Thus, orangutans' survivorship under natural conditions is expected to be extremely high. Previous estimates of orangutan life history were based on captive individuals living under very different circumstances or on small samples from wild populations. Here, we combine birth data from seven field sites, each with demographic data collection for at least 10 years (range 12-43 years) on wild orangutans to better document their life history. Using strict criteria for data inclusion, we calculated infant survival, interbirth intervals and female age at first reproduction, across species, subspecies and islands. We found an average closed interbirth interval of 7.6 years, as well as consistently very high pre-weaning survival for males and females. Female survival of 94% until age at first birth (at around age 15 years) was higher than reported for any other mammal species under natural conditions. Similarly, annual survival among parous females is very high, but longevity remains to be estimated. Current data suggest no major life history differences between Sumatran and Bornean orangutans. The high offspring survival is remarkable, noting that modern human populations seem to have reached the same level of survival only in the 20th century. The orangutans' slow life history illustrates what can be achieved if a hominoid bauplan is exposed to low unavoidable mortality. Their high survival is likely due to their arboreal and non-gregarious lifestyle, and has allowed them to maintain viable populations, despite living in low-productivity habitats. However, their slow life history also implies that orangutans are highly vulnerable to a catastrophic population crash in the face of drastic habitat change.


Assuntos
Longevidade , Pongo pygmaeus/fisiologia , Desmame , Animais , Feminino , Indonésia , Masculino , Pongo abelii
8.
Sci Adv ; 4(11): eaau3401, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30443595

RESUMO

One of the defining features of language is displaced reference-the capacity to transmit information about something that is not present or about a past or future event. It is very rare in nature and has not been shown in any nonhuman primate, confounding, as such, any understanding of its precursors and evolution in the human lineage. Here, we describe a vocal phenomenon in a wild great ape with unparalleled affinities with displaced reference. When exposed to predator models, Sumatran orangutan mothers temporarily suppressed alarm calls up to 20 min until the model was out of sight. Subjects delayed their vocal responses in function of perceived danger for themselves, but four major predictions for stress-based mechanisms were not met. Conversely, vocal delay was also a function of perceived danger for another-an infant-suggesting high-order cognition. Our findings suggest that displaced reference in language is likely to have originally piggybacked on akin behaviors in an ancestral hominid.


Assuntos
Comunicação Animal , Cognição/fisiologia , Pongo abelii/fisiologia , Vocalização Animal/fisiologia , Animais , Animais Recém-Nascidos , Evolução Biológica , Feminino , Fatores de Tempo
9.
Sci Rep ; 8(1): 16518, 2018 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-30410111

RESUMO

Betty the crow astonished the scientific world as she spontaneously crafted hook-tools from straight wire in order to lift a basket out of vertical tubes. Recently it was suggested that this species' solution was strongly influenced by predispositions from behavioural routines from habitual hook-tool manufacture. Nevertheless, the task became a paradigm to investigate tool innovation. Considering that young humans had surprising difficulties with the task, it was yet unclear whether the innovation of a hooked tool would be feasible to primates that lacked habitual hook making. We thus tested five captive orangutans in a hook bending and unbending task. Orangutans are habitually tool-using primates that have been reported to use but not craft hooked tools for locomotion in the wild. Two orangutans spontaneously innovated hook tools and four unbent the wire from their first trial on. Pre-experience with ready-made hooks had some effect but did not lead to continuous success. Further subjects improved the hook-design feature when the task required the subjects to bent the hook at a steeper angle. Our results indicate that the ability to represent and manufacture tools according to a current need does not require stereotyped behavioural routines, but can indeed arise innovatively. Furthermore, the present study shows that the capacity for hook tool innovation is not limited to large brained birds within non-human animals.


Assuntos
Pongo abelii/fisiologia , Comportamento Estereotipado/fisiologia , Comportamento de Utilização de Ferramentas/fisiologia , Animais , Comportamento Alimentar/fisiologia , Feminino , Locomoção , Masculino
10.
J Comp Psychol ; 132(4): 419-426, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30024236

RESUMO

Formal training programs, which can be called education, enhance cognition in human and nonhuman animals alike. However, even informal exposure to human contact in human environments can enhance cognition. We review selected literature to compare animals' behavior with objects among keas and great apes, the taxa that best allow systematic comparison of the behavior of wild animals with that of those in human environments such as homes, zoos, and rehabilitation centers. In all cases, we find that animals in human environments do much more with objects. Following and expanding on the explanations of several previous authors, we propose that living in human environments and the opportunities to observe and manipulate human-made objects help to develop motor skills, embodied cognition, and the use of objects to extend cognition in the animals. Living in a human world also furnishes the animals with more time for such activities, in that the time needed for foraging for food is reduced, and furnishes opportunities for social learning, including emulation, an attempt to achieve the goals of a model, and program-level imitation, in which the imitator reproduces the organizational structure of goal-directed actions without necessarily copying all the details. All these factors let these animals learn about the affordances of many objects and make them better able to come up with solutions to physical problems. (PsycINFO Database Record (c) 2018 APA, all rights reserved).


Assuntos
Comportamento Animal/fisiologia , Cognição/fisiologia , Hominidae/fisiologia , Comportamento Imitativo/fisiologia , Psittaciformes/fisiologia , Desempenho Psicomotor/fisiologia , Aprendizado Social/fisiologia , Animais , Animais Selvagens , Animais de Zoológico , Meio Ambiente , Gorilla gorilla , Pan paniscus , Pongo abelii , Pongo pygmaeus , Comportamento de Utilização de Ferramentas/fisiologia
11.
PLoS One ; 13(6): e0199200, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29912972

RESUMO

The hepatic Na+/taurocholate co-transporting polypeptide (NTCP in man, Ntcp in animals) is the high-affinity receptor for the hepatitis B (HBV) and hepatitis D (HDV) viruses. Species barriers for human HBV/HDV within the order Primates were previously attributed to Ntcp sequence variations that disable virus-receptor interaction. However, only a limited number of primate Ntcps have been analysed so far. In the present study, a total of 11 Ntcps from apes, Old and New World monkeys were cloned and expressed in vitro to characterise their interaction with HBV and HDV. All Ntcps showed intact bile salt transport. Human NTCP as well as the Ntcps from the great apes chimpanzee and orangutan showed transport-competing binding of HBV derived myr-preS1-peptides. In contrast, all six Ntcps from the group of Old World monkeys were insensitive to HBV myr-preS1-peptide binding and HBV/HDV infection. This is basically predetermined by the amino acid arginine at position 158 of all studied Old World monkey Ntcps. An exchange from arginine to glycine (as present in humans and great apes) at this position (R158G) alone was sufficient to achieve full transport-competing HBV myr-preS1-peptide binding and susceptibility for HBV/HDV infection. New World monkey Ntcps showed higher sequence heterogeneity, but in two cases with 158G showed transport-competing HBV myr-preS1-peptide binding, and in one case (Saimiri sciureus) even susceptibility for HBV/HDV infection. In conclusion, amino acid position 158 of NTCP/Ntcp is sufficient to discriminate between the HBV/HDV susceptible group of humans and great apes (158G) and the non-susceptible group of Old World monkeys (158R). In the case of the phylogenetically more distant New World monkey Ntcps amino acid 158 plays a significant, but not exclusive role.


Assuntos
Vírus da Hepatite B/fisiologia , Hepatite B/veterinária , Transportadores de Ânions Orgânicos Dependentes de Sódio/metabolismo , Simportadores/metabolismo , Animais , Callithrix/genética , Chlorocebus aethiops/genética , Clonagem Molecular , Células HEK293 , Células Hep G2 , Hepatite B/transmissão , Humanos , Macaca/genética , Macaca fascicularis/genética , Macaca mulatta/genética , Transportadores de Ânions Orgânicos Dependentes de Sódio/genética , Pan troglodytes/genética , Papio anubis/genética , Papio hamadryas/genética , Pongo abelii/genética , Saguinus/genética , Saimiri/genética , Alinhamento de Sequência , Simportadores/genética , Transfecção
12.
J Comp Psychol ; 132(3): 294-305, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29708360

RESUMO

Many primate species have a strong disposition to approach and manipulate objects in captivity. However, few studies have investigated what primates learn during free exploration of objects in the absence of rewards, and how previous problem-solving performance influences subsequent exploration. We confronted members of each of the four nonhuman great ape species (N = 25) with the collapsible platform task that required subjects to drop a stone inside a tube to collapse a platform and release a reward. Subjects received four successive sessions with an empty apparatus (exploration driven by intrinsic motivation) followed by four with a baited apparatus (problem-solving driven by extrinsic motivation) or vice versa. Apes who first faced an empty apparatus solved the task more quickly in the baited condition than apes who started with this condition. Moreover, apes starting with the baited condition took longer to collapse the platform in the first trial than apes who started with the empty condition. This study suggests that apes exposed to an empty apparatus before the test gain information that is later used to solve the task in a more efficient manner. Thus, apes learn about action-outcome contingencies during free exploration. Moreover, it indicates that the presence of food rewards distracts apes and delays problem-solving because apes' attention is mainly focused on the food. (PsycINFO Database Record


Assuntos
Comportamento Exploratório , Gorilla gorilla , Motivação , Pan paniscus , Pan troglodytes , Pongo abelii , Resolução de Problemas , Recompensa , Animais , Atenção , Feminino , Masculino , Pongo pygmaeus , Retenção Psicológica
13.
Am J Primatol ; 80(6): e22872, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29756687

RESUMO

The importance of smell in humans is well established but we know little about it in regard to our closest relatives, the great apes, as systematic studies on their olfactory behavior are still lacking. Olfaction has long been considered to be of lesser importance in hominids given their relatively smaller olfactory bulbs, fewer functional olfactory receptor genes than other species and absence of a functional vomeronasal organ. Therefore, the aim of this study was to evaluate the use of olfaction in hominids. In particular, we observed sniffing behavior in captive groups of four species (Sumatran orangutans, Pongo abelii; Western lowland gorillas, Gorilla gorilla gorilla; Western chimpanzees, Pan troglodytes verus; bonobos, Pan paniscus) and evaluated in which contexts sniffing was used. Our results show that all investigated species frequently used the sense of smell, and that the sniffing frequency varied with species, sex, age, and context. Most sniffing events were observed in gorillas in comparison to the three other species. Sniffing frequencies were also influenced by sex, with males sniffing slightly more often than females. Furthermore, our results revealed an effect of age, with younger individuals sniffing more often than older individuals. All species mainly sniffed in the non-social context (i.e., toward food and other environmental items) rather than in the social context (i.e., at conspecifics), suggesting that the evaluation of the environment and the nutritional value of food items is of major importance to all great ape species investigated here. In contrast to the other species and female chimpanzees, however, male chimpanzees most often used olfaction to inspect their conspecifics. Together, our study suggests that olfaction is likely to be more important in great apes than previously appreciated.


Assuntos
Gorilla gorilla/fisiologia , Pan paniscus/fisiologia , Pan troglodytes/fisiologia , Pongo abelii/fisiologia , Olfato/fisiologia , Fatores Etários , Animais , Comportamento Animal/fisiologia , Feminino , Alimentos , Masculino , Fatores Sexuais , Comportamento Social
14.
J Med Primatol ; 47(3): 201-204, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29493782

RESUMO

Strongyloides nematodes have been reported in all species of great apes with orangutans ≤5 years old most susceptible to severe clinical disease. This brief communication describes the first published case of antemortem diagnosis and treatment of disseminated strongyloidiasis in a clinically affected 5-month-old Sumatran orangutan (Pongo abelii).


Assuntos
Doenças dos Símios Antropoides/terapia , Pongo abelii , Strongyloides/isolamento & purificação , Estrongiloidíase/terapia , Animais , Animais de Zoológico , Doenças dos Símios Antropoides/diagnóstico , Feminino , Estrongiloidíase/diagnóstico
15.
Sci Rep ; 7(1): 16866, 2017 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-29203828

RESUMO

The gene coding for the forkhead box protein P2 (FOXP2) is associated with human language disorders. Evolutionary changes in this gene are hypothesized to have contributed to the emergence of speech and language in the human lineage. Although FOXP2 is highly conserved across most mammals, humans differ at two functional amino acid substitutions from chimpanzees, bonobos and gorillas, with an additional fixed substitution found in orangutans. However, FOXP2 has been characterized in only a small number of apes and no publication to date has examined the degree of natural variation in large samples of unrelated great apes. Here, we analyzed the genetic variation in the FOXP2 coding sequence in 63 chimpanzees, 11 bonobos, 48 gorillas, 37 orangutans and 2 gibbons and observed undescribed variation in great apes. We identified two variable polyglutamine microsatellites in chimpanzees and orangutans and found three nonsynonymous single nucleotide polymorphisms, one in chimpanzees, one in gorillas and one in orangutans with derived allele frequencies of 0.01, 0.26 and 0.29, respectively. Structural and functional protein modeling indicate a biochemical effect of the substitution in orangutans, and because of its presence solely in the Sumatran orangutan species, the mutation may be associated with reported population differences in vocalizations.


Assuntos
Fatores de Transcrição Forkhead/genética , Variação Genética , Vocalização Animal/fisiologia , Sequência de Aminoácidos , Animais , Evolução Biológica , Fatores de Transcrição Forkhead/química , Fatores de Transcrição Forkhead/metabolismo , Frequência do Gene , Gorilla gorilla/genética , Hominidae , Repetições de Microssatélites/genética , Pan paniscus/genética , Pan troglodytes/genética , Polimorfismo de Nucleotídeo Único , Pongo abelii/genética , Pongo pygmaeus/genética , Estrutura Secundária de Proteína , Alinhamento de Sequência
16.
Science ; 358(6363): 572-573, 2017 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-29097524
17.
Sci Rep ; 7(1): 15464, 2017 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-29133851

RESUMO

It has been hypothesized that opportunities for social learning affect the size and complexity of the adult skill set of birds and mammals, their learning ability, and thus ultimately also their innovation frequency. To test these predictions we compared rates of social learning, rates of independent exploration (independent learning) and innovation repertoires between individuals of a highly sociable population of Pongo abelii at Suaq Balimbing and a less sociable population of Pongo pygmaeus wurmbii at Tuanan. Suaq immatures showed significantly higher rates of peering, even after controlling for differences in association time and diet complexity, implying that they make disproportionally greater use of their increased opportunities for social learning. As predicted, we found that immatures and adults at Suaq also showed significantly higher rates of exploratory behaviour. The difference between the individuals of the two popuations remained when controlling for association time, suggesting persistent developmental effects, intrinsic differences, or both. Accordingly, Suaq animals had a larger set of learned skills and a higher mean dietary complexity. Our findings show that population level sociability, individual rates of exploration and population-wide repertoires of innovations are positively linked, as predicted.


Assuntos
Comportamento Animal/fisiologia , Comportamento Exploratório/fisiologia , Pongo abelii/psicologia , Pongo pygmaeus/psicologia , Comportamento Social , Animais , Técnicas de Observação do Comportamento , Feminino , Masculino , Grupo Associado
18.
Curr Biol ; 27(22): 3487-3498.e10, 2017 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-29103940

RESUMO

Six extant species of non-human great apes are currently recognized: Sumatran and Bornean orangutans, eastern and western gorillas, and chimpanzees and bonobos [1]. However, large gaps remain in our knowledge of fine-scale variation in hominoid morphology, behavior, and genetics, and aspects of great ape taxonomy remain in flux. This is particularly true for orangutans (genus: Pongo), the only Asian great apes and phylogenetically our most distant relatives among extant hominids [1]. Designation of Bornean and Sumatran orangutans, P. pygmaeus (Linnaeus 1760) and P. abelii (Lesson 1827), as distinct species occurred in 2001 [1, 2]. Here, we show that an isolated population from Batang Toru, at the southernmost range limit of extant Sumatran orangutans south of Lake Toba, is distinct from other northern Sumatran and Bornean populations. By comparing cranio-mandibular and dental characters of an orangutan killed in a human-animal conflict to those of 33 adult male orangutans of a similar developmental stage, we found consistent differences between the Batang Toru individual and other extant Ponginae. Our analyses of 37 orangutan genomes provided a second line of evidence. Model-based approaches revealed that the deepest split in the evolutionary history of extant orangutans occurred ∼3.38 mya between the Batang Toru population and those to the north of Lake Toba, whereas both currently recognized species separated much later, about 674 kya. Our combined analyses support a new classification of orangutans into three extant species. The new species, Pongo tapanuliensis, encompasses the Batang Toru population, of which fewer than 800 individuals survive. VIDEO ABSTRACT.


Assuntos
Especiação Genética , Pongo/genética , Animais , Comportamento Animal/fisiologia , Evolução Biológica , Espécies em Perigo de Extinção , Fluxo Gênico/genética , Variação Genética , Genoma , Genômica , Hominidae/genética , Metagenômica/métodos , Filogenia , Pongo/classificação , Pongo/fisiologia , Pongo abelii/genética , Pongo pygmaeus/genética
20.
Am J Primatol ; 79(10)2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28877364

RESUMO

Inductive learning from limited observations is a cognitive capacity of fundamental importance. In humans, it is underwritten by our intuitive statistics, the ability to draw systematic inferences from populations to randomly drawn samples and vice versa. According to recent research in cognitive development, human intuitive statistics develops early in infancy. Recent work in comparative psychology has produced first evidence for analogous cognitive capacities in great apes who flexibly drew inferences from populations to samples. In the present study, we investigated whether great apes (Pongo abelii, Pan troglodytes, Pan paniscus, Gorilla gorilla) also draw inductive inferences in the opposite direction, from samples to populations. In two experiments, apes saw an experimenter randomly drawing one multi-item sample from each of two populations of food items. The populations differed in their proportion of preferred to neutral items (24:6 vs. 6:24) but apes saw only the distribution of food items in the samples that reflected the distribution of the respective populations (e.g., 4:1 vs. 1:4). Based on this observation they were then allowed to choose between the two populations. Results show that apes seemed to make inferences from samples to populations and thus chose the population from which the more favorable (4:1) sample was drawn in Experiment 1. In this experiment, the more attractive sample not only contained proportionally but also absolutely more preferred food items than the less attractive sample. Experiment 2, however, revealed that when absolute and relative frequencies were disentangled, apes performed at chance level. Whether these limitations in apes' performance reflect true limits of cognitive competence or merely performance limitations due to accessory task demands is still an open question.


Assuntos
Cognição , Hominidae , Animais , Alimentos , Gorilla gorilla , Aprendizagem , Pan paniscus , Pan troglodytes , Pongo abelii , Pongo pygmaeus
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