Study of intellectual activity at recognition of numerical multitudes of two-dimensional and three-dimensional stimuli of different color in lower monkeys

The capability of monkeys for recognition and comparison by identity of two-dimensional images and three-dimensional objects of different color and number (from 1 to 5) was studied at solution of tasks of the “selection by sample” type. The study was carried out on two species of the lower monkeys of different levels of phylogenetic development: rhesus macaques (Macaca mulatta) and brown capuchins (Cebus apella). Representatives of the studied monkey species were established to able to differentiate two-dimensional stimuli (images of squares) and three-dimensional stimuli (objects of rounded shape) of red, yellow, and green color in different quantitative ratios (from 1 to 5) by selecting identical signs when solving modifications of the “selection by sample” tasks. The obtained data indicate the presence in primates of numerical notion and their ability to differentiate objects in the number from 1 to 5 regardless of the color of these objects. Speciesspecific differences in monkeys were revealed; rhesus macaques, as compared with capuchins, experienced difficulties at solution of complex combinatory tasks. The obtained experimental results give grounds to believe the presence in the lower monkeys the notion “quantity” as well as of the sufficiently high level of pre-verbal thinking.     

Study of capability for recognition of complex visual stimuli of different quantities in the lower monkeys

Capability of monkeys for identification of quantitative signs has been studied at recognition and comparison of two-and three-dimensional objects in quantities from 1 to 8. The work was carried out on two species of the lower monkeys: rhesus macaque (Macaca mulatto) and brown capuchins (Cebus apella). The studied representatives of the monkeys have been established to be able to differentiate planar images and casts of cherries in various quantity combinations from 1 to 8 and to identify identical signs of visual stimuli. The obtained data indicate the ability of monkeys to abstract and to form preverbal notions of quantitative signs of objects.     

Peculiarities of recognition and comparison by size of two-dimensional images and three-dimensional objects of different colors in the lower monkeys

The ability of monkeys to recognize and compare two-dimensional images and three-dimensional objects of different colors by size was studied. The study was carried out on two species of monkey of different level of phylogenetic development: rhesus macaques (Macaca mulatta) and brown capuchin (Cebus apella). The monkeys were established to be able to recognize and to compare by size the two-dimensional pictures and three-dimensional objects of red, yellow, and green colors with identification of the relative sign “more.” Solution of visual tasks of the “more-less” type was achieved at any combination of stimuli regardless of color. The age-and specie-related differences were revealed during the course of training. In all monkeys the “transfer of learning” and formation of generalization were traced. This indicates a sufficiently well developed level of elementary thinking in the lower monkeys.     

Comparative Physiological Study of the Processes of Recognition of Different Numbers of Two- and Three-Dimensional Objects and Their Identification in Lower and Higher Monkeys

The capability of monkeys for comparison and identification of plane images and three-dimensional objects has been studied using tasks of the sample choice type. The study was performed on three species of monkeys with different level of phylogenic development: rhesus macaques Macaca mulatta, brown capuchins Cebus apella, and chimpanzee Pan troglodites. It has been established that representatives of the studied species are able to differentiate two-dimensional images of berries and corresponding three-dimensional models in various quantitative ratios from 1 to 5 and to choose identical signs of stimuli in solving problems of the sample choice type. These circumstances argue in favor of the existence of quantitative notions in primates and their capability of counting in the limits from 1 to 5. Rhesus macaques had difficulties in solving complicated combinatory tasks. The obtained facts indicate a sufficiently high level of the pre-verbal cognition in primates.     

Comparative-Physiological Study of Peculiarities of Recognition of Two-Dimensional Images and Three-Dimensional Objects of Different Color and Their Identification in Lower and Higher Monkeys

The ability of monkeys to recognize visual stimuli as well as to collate and identify two-dimensional images and three-dimensional objects of different color was studied at their solving tasks of different degree of complexity. The study was performed on three species of monkeys of different levels of phylogenetic development: rhesus macaques Macaca mulatta, black-capped capuchins Cebus apella, and chimpanzee Pan troglodites. It has been established that representatives of the studied monkey species are capable of recognizing two-dimensional images and three-dimensional objects of the green, red, and yellow colors, of their collating and identifying. The differentiation of signals and the correct selection by color have been shown to be performed at solution of visual tasks of different degree of complexity by using different methodical approaches. In the course of learning, in all monkeys the transfer of the learning and formation of generalization are observed. This indicates a sufficiently well-developed level of elementary thinking in primates.     

Comparative Physiological Investigation of Peculiarities of Recognition of Complex Visual Images and Ability to Identify Two-Dimensional Images and Three-Dimensional Objects by the Lower and Higher Monkeys

An ability of primates to compare and identify planar images and three-dimensional objects has been studied at solving tasks of the choice on model type. The study is carried out on three species of monkeys of different levels of phylogenetic development: macaques rhesuses Macaca mulata, brown capuchins Cebus apella, and chimpanzee Pan troglodytes. Plaster casts of fruits, household objects, and toys–animals were used for the identification. It is revealed that representatives of the studied monkey species are able to compare and identify three-dimensional objects and their two-dimensional images and to extract identical attributes during solution of visual tasks of different degrees of complexity in variants of the methodical approach choice on model. Under conditions of our experiments, the capuchins, macaques, and chimpanzee performed a direct transfer of the elaborated principle of the solution. There have also been established peculiarities of behavior of different species of the lower and higher monkeys. Macaques rhesuses had difficulties when solving complex combinatory tasks. Capuchins displayed pronounced negative emotions and characteristic patterns of defensive behavior at demonstration and during identification of two- and three-dimensional objects of the toys–animals type. Unlike the lower monkeys, the chimpanzee, when presented with toys–animals, did not change the level of their correct answers and demonstrated pronounced play reactions.     

Hierarchical complexity of combinatorial manipulation in capuchin monkeys (Cebus apella)

The purpose of this study was to examine the hierarchical complexity of combinatorial manipulation in capuchin monkeys (Cebus apella). Two experiments were conducted. In Experiment 1 capuchins were presented with an apparatus designed to accommodate the use of probing tools. In Experiment 2 the same capuchins were presented with sets of nesting containers. Five of the ten subjects used probing tools and seven subjects placed objects in the containers. The capuchins' behavior reflected three hierarchically organized combinatorial patterns displayed by chimpanzees and human infants. Although the capuchins sometimes displayed the two more complex patterns (“pot” and “subassembly”), their combinatorial behavior was dominated by the simplest pattern (“pairing”). In this regard capuchins may not attain the same grammar of manipulative action that has been reported for chimpanzees and young human children. © 1994 Wiley-Liss, Inc.     

Picture processing in tufted capuchin monkeys (Cebus apella)

Although pictures are frequently used in place of real objects to investigate various aspects of cognition in different non-human species, there is little evidence that animals treat pictorial stimuli as representations of the real objects. In the present study, we carried out four experiments designed to assess picture processing in tufted capuchin monkeys (Cebus apella), using a simultaneous Matching-to-Sample (MTS) task. The results of the first three experiments indicate that capuchins are able to match objects with their colour photographs and vice versa, and that object-picture matching in this New World monkey species is not due to picture-object confusion. The results of the fourth experiment show that capuchins are able to recognize objects in their pictures with a high level of accuracy even when less realistic images, such as black-and-white photographs, silhouettes and line drawings, are employed as bi-dimensional stimuli. Overall, these findings indicate that capuchin monkeys are able to establish a correspondence between the real objects and their pictorial representations.     

Does Presentation Format Influence Visual Size Discrimination in Tufted Capuchin Monkeys (Sapajus spp.)?

Most experimental paradigms to study visual cognition in humans and non-human species are based on discrimination tasks involving the choice between two or more visual stimuli. To this end, different types of stimuli and procedures for stimuli presentation are used, which highlights the necessity to compare data obtained with different methods. The present study assessed whether, and to what extent, capuchin monkeys’ ability to solve a size discrimination problem is influenced by the type of procedure used to present the problem. Capuchins’ ability to generalise knowledge across different tasks was also evaluated. We trained eight adult tufted capuchin monkeys to select the larger of two stimuli of the same shape and different sizes by using pairs of food items (Experiment 1), computer images (Experiment 1) and objects (Experiment 2). Our results indicated that monkeys achieved the learning criterion faster with food stimuli compared to both images and objects. They also required consistently fewer trials with objects than with images. Moreover, female capuchins had higher levels of acquisition accuracy with food stimuli than with images. Finally, capuchins did not immediately transfer the solution of the problem acquired in one task condition to the other conditions. Overall, these findings suggest that – even in relatively simple visual discrimination problems where a single perceptual dimension (i.e., size) has to be judged – learning speed strongly depends on the mode of presentation.     

Forelimb dimensions and goniometry of the wrist and fingers in tufted capuchin monkeys (Cebus apella): Developmental and comparative aspects

Adult capuchin monkeys use precision grips during manipulation of small objects, although their thumbs have been classified as pseudo-opposable. We investigated the physical properties of the hands to increase our understanding of manual function in capuchins. Forelimb dimensions and joint mobility (goniometric) measurements were obtained from adult, juvenile, and infant tufted capuchins (Cebus apella). Compared to adult squirrel monkeys, adult capuchins exhibited less flexibility of the wrist and digits. Capuchins of all ages had proportionally longer hands than squirrel monkeys, and capuchins more than 7 weeks old had proportionally longer thumbs than squirrel monkeys. Growth of the arms and hands was asynchronous. The duration of growth of the thumb was particularly prolonged, extending into early adulthood. Age-related changes in flexibility were apparent in most indices, and were greatest at the metacarpophalangeal joints. It is unknown to what extent the characteristics of growth, forelimb dimensions, and goniometry presented by capuchins are shared with other species, or if they contribute to the capuchin's unusual prehensive capacities. However, the marked differences between adult capuchins and squirrel monkeys in these metrics, and between capuchins and rhesus in the growth patterns of the digits, suggest that variation across taxa in these characteristics can be considerable.     

Field Anesthesia and Health Assessment of Free-ranging <Emphasis Type="Italic">Cebus capucinus</Emphasis> in Panama

Health and disease are critical factors for understanding primate evolution and for developing effective conservation and management strategies. However, comprehensive health assessments of wild primate populations are rare, in part because of the difficulty and risk of chemically immobilizing subjects to obtain the necessary biological samples. We report here the results of a health assessment, as well as the methods and drug dosages used to capture white-faced capuchins (Cebus capucinus) on Barro Colorado Island, Panama. We captured and measured 24 capuchins as part of an ongoing radiotelemetry study, and collected biological samples from 9 of them for a comprehensive health survey. Telazol® was very effective for immobilizing and capturing capuchins, although the doses we used were higher than those recommended for captive capuchins. High Telazol doses immobilized individuals quickly, ensuring that we were able to find and recover the sedated monkeys. The capuchins were generally in good condition, and had few ecto-, hemo-, or intestinal parasites. However, all but 1 of the adults had substantial dental abnormalities. In addition, 1 juvenile had indeterminate genitalia that we believe to be the result of hypospadias. Seven of the capuchins tested positive for exposure to Herpesvirus tamarinus and all individuals tested positive for exposure to Cebus cytomegalovirus. Hematology, serum chemistry, and plasma mineral levels from the wild individuals were, for the most part, comparable to those recorded for captive Cebus capucinus, and contribute to establishing baseline health values for the species.     

Intellectual activity during formation of quantitative concepts in the lower and higher monkeys

Results of study of formation of quantitative concepts in the lower and higher monkey are presented. Various authors used different methods of study of this issue. It has been established that not only the higher primates, such as chimpanzees and orangutans, but also the lower ones—macaques, capuchins, squirrel monkeys—have the “mathematical capabilities.” The detailed study of formation of quantitative concepts in primates of different levels of phylogenesis allows disclosing mechanisms of formation of this function in human.     

The ability of rhesus macaques to perform elementary mathematical actions

Rhesus macaques were presented as an example with multitudes in the range from 1–2 to 5–6 “dots,” 10 mm in diameter, on the monitor screen. By consecutive discrete pressing the key with “+” symbol, the monkeys formed on the “field of counting” a randomized multitude equal to that presented as an example. O. Koehler’s hypothesis of connection between counting and thinking and the proximity of the consecutive effector form of counting to discrete nature of human language is discussed.     

Extraction of hermit crabs from their shells by white-faced capuchin monkeys (<Emphasis Type="Italic">Cebus capucinus</Emphasis>)

We observed two capuchin monkeys (Cebus capucinus) feeding on hermit crabs (Coenobita compressus) on the coast, and the tactics they used to extract this well-protected prey. The observations took place during the dry season at Playa Escondida beach, Puntarenas, Costa Rica. The capuchins descended from trees at the back edge of the beach to capture passing hermit crabs. Both capuchins extracted the hermit crabs from their protective shells by holding the shell with one hand and pulling the crab out with the other. Even though this was accomplished within seconds, the extraction of hermit crabs from their shells did not appear to be a straightforward task. Once the capuchins succeeded in pulling the crabs out of their shells, they consumed the soft abdomen and discarded the rest of the crab's body. To our knowledge, the consumption of hermit crabs has not been previously reported for any capuchin monkey (Cebus or Sapajus). Our observations provide a new example of extractive foraging by capuchins, and thus an additional natural context for which fine motor skills (which are highly developed in capuchins) are necessary.     

Multifractal Characterization of Butterfly Wings Scales

A lot of insect families have physical structures created by evolution for coloration. These structures are a source of ideas for new bio-inspired materials. The aim of this study was to quantitatively characterize the micromorphology of butterfly wings scales using atomic force microscopy and multifractal analysis. Two types of butterflies, Euploea mulciber (“striped blue crow”) and Morpho didius (“giant blue morpho”), were studied. The three-dimensional (3D) surface texture of the butterfly wings scales was investigated focusing on two areas: where the perceived colors strongly depend on and where they do not depend on the viewing angle. The results highlight a correlation between the surface coloration and 3D surface microtexture of butterfly wings scales.     

The Notions of Size and Shape in Old World Monkeys (<Emphasis Type="Italic">Macaca mullata</Emphasis>): A Comparative Analysis of the Formation Process

In everyday life, humans and animals occupying different rungs of the “evolutionary ladder” often have to evaluate the notions of larger/smaller size (predator/prey, rival/ally, etc.) and flat/volumetric shape (fruit/leaf, 2D/3D images, etc.). The aim of this study was to find out experimentally which of the following two tasks related to the formation of the preverbal notions of larger/smaller size or flat/volumetric shape is easier to train rhesus monkeys. The first task was to form or actualize the notion of larger or smaller size upon co-presentation of 4 flat or volumetric figures. The second task was to form or actualize the notion of flat or volumetric object among 4 figures of the same size (small, medium or large) presented simultaneously. To be rewarded during the formation of both notions, the animal was supposed to choose a figure which was different from the other three in the trial. In both tasks, the number of trials required to reach or exceed the 70% level of correct task implementation per each type of training was counted. This allowed optimization of the notion formation algorithm to rule out strong skill consolidation (overtraining) that might inhibit the formation of a new skill in further training. When the number of trials was averaged over all types of training, the notion of shape formed faster than the notion of size. This discrepancy was only observed under the difficulty of solving one of the task types–discriminating between objects poorly distinguishable (1.5 times) by their size. However, in the situation of no difficulty in discriminating between figures during their perception (more than a 2-fold difference in size), the number of trials in forming the notions of size and shape was statistically indistinguishable. Since training rates in forming the notions of larger/smaller size or flat/volumetric shape were indistinguishable in simple choice situations, we suggest that these notions are equally important for rhesus monkeys.     

Gender Differences in Spontaneous and Evoked Activities of the Human Brain

The purpose of this study was to analyze sex-related differences in spontaneous and evoked brain activity. The study included 11 women and 10 men aged between 18 and 27 years; the subjects were adapted to the conditions of electrophysiological experiment. Differences in spontaneous activity were estimated by EEG spectral characteristics in frequency ranges corresponding to θ, α, β₁, β₂, γ₁, and γ₂ rhythms at rest with the eyes open and closed. The differences in evoked activity were estimated by the parameters of evoked potentials (EP) recorded upon the presentation of different types of stimuli (images and words) and categories (“fruits” and “vessels”). Behavioral differences were estimated by the efficiency of stimuli recognition. No gender differences were observed in the efficiency of stimuli recognition (number of errors, time of reaction). In the EEG of male subjects at rest, fast frequencies (β and γ) were less marked than in the female subjects, which may indicate a higher level of activation of CNS structures in women. Regardless of stimuli type and category, the amplitude of EP components in men is lower than that in women, which may be caused by lower level of CNS activation. However, the difference in the latency of EP components depended on the type of stimuli used. During the recognition of visual images, the latency of earlier EP components (N1, P2) in men was longer mostly on back and/or right electrodes. The latencies of the later EP components (P3, N3) in male subjects were longer on the back electrodes and shorter on the front electrodes than those in female ones. During the recognition of words, the latency of P1, N1, P2 and N2 components in men were shorter on temporal and temporoparietal electrodes of the left hemisphere. This may indicate that visual image in men are perceived slower but comprehended faster than in women. On the other hand, verbal stimuli in men were perceived faster but comprehended slower than in women.     

Illumina-sequencing based transcriptome study of coat color phenotypes in domestic goats

This study performed a comprehensive expression profiling of genes expressed in the skin of goats with three different coat colors by Illumina Sequencing. A total of 91 significantly expressed genes were detected when comparing gray skin to white skin library and these included 74 up-regulated and 17 down-regulated genes in gray skin. There were 67 differentially expressed genes between brown skin and white skin libraries, 23 of which were up-regulated and 44 were down-regulated in brown skin. When we compared brown and gray libraries, 154 differentially expressed genes were found, of which 33 showed higher expression and 121 showed lower expression in brown skin. To our surprise, MC1R, MITF, TYR and KIT showed no significant difference in expression between the goats with three skin colors, whereas ASIP was detected in white skin but not in dark skins. In this study, PMEL, TRPM1, TYRP1 and DCT were significantly up-regulated in brown goat skin compare with gray and white skins. PMEL showed higher expression in gray goat skin compared with white goat skin, whereas there were no significant differences in the expression of TYRP1, TRPM1 and DCT between gray and white skin samples. In addition, ELOVL3 showed higher expression in gray goat skin than in brown and white skins, whereas there was no significant differences in the expression of ELOVL3 between brown and white skin samples. These results expand our understanding of the complex molecular mechanisms of skin physiology and melanogenesis in goat and provide a foundation for future studies.     

Isozymes as bioprobes for genetic analysis of nonhuman primates

The identification and the utilization of genetically determined electrophoretic differences of enzymes between the individuals of species as well as between cell lines have played an important role in the advancement of mammalian genetics during the past quarter of a century. In an explicit search we found a number of red cell enzyme polymorphisms in each of the following four species: chimpanzees, orang utans, rhesus monkeys and brown capuchins. Allelic distribution patterns among populations have indicated trends of subspeciation among chimpanzees and orang utans due to geographic barriers leading to reproductive isolation. Investigations of quantitative levels of red cell glucose-6-phosphate dehydrogenase have suggested that relative activity profiles of certain enzymes among species may be helpful in studies of the evolution of physiological traits and their biological significance during speciation. A large number of biochemical genetic markers in primate-rodent (i.e., chimpanzee-, gorilla-, orang utan-, rhesus monkey- and African green monkey-Chinese hamster) somatic cell hybrids have been identified and are useful for primate genetic analysis. Some of the biologically relevant observations on the enzyme markers in the above mentioned primate species are discussed.     

Primate Community Structure in Guyana: A Biogeographic Analysis

Studies of primate community structure increase our understanding of behavior, adaptation, and evolution. However, there are few biogeographic data on specific composition and association patterns in primate communities. I conducted a biogeographic analysis of the community structure of primate species at 16 sites in Guyana. I used data from 1725 km of line-transect censuses to determine specific composition and association patterns of 220 primate groups . Of the 18 polyspecific groups, 94.1% (N = 16) included squirrel monkeys. There was an overall trend towards positive specific associations among Guyanese primates. The only species that exhibited a negative pattern of interspecific associations were brown and wedge-capped capuchins. The sighting rate for wedge-capped capuchins at sympatric sites was particularly depressed compared to that for brown capuchins. Low plant productivity in Guyanese forests may reduce the diversity of feeding niches and result in a low incidence of polyspecific associations and scramble competition between wedge-capped and brown capuchins.