Infant Chimpanzees Research Articles

Protection of the Infant Thyroid from Radioactive Contamination by the Administration of Stable Iodide. An Experimental Evaluation in Chimpanzees

Protection of the thyroid from radioactive contamination by the administration of stable iodide was investigated in chimpanzees aged 2 to 98 weeks. The uptake of iodide in the thyroid was measured with 123I-. The animals were subjected to a control measurement first, and subsequently the thyroid uptake of 123I- was determined twice; once at the start and once at the end of 11 days of ingestion of 0.5, 1.5 or 5.0 mg of stable iodide per kg body weight per day. The three doses of iodide reduced the control thyroid iodide uptake of 10 to 30% to lower than 1% when ingested 1 h before exposure to the tracer and to 2-4% when ingested 20 h before exposure. In the latter experiments 0.5 mg iodide/kg was less effective than doses of 1.5 mg/kg or higher. The physiological state of the thyroid of control infant chimpanzees does not differ from that of human infants. Incidentally, an increased level of TSH was found during the ingestion of iodide, but with unaltered thyroxine levels. Therefore, it is concluded that a daily dose of 1.5 mg stable iodide/kg body weight and higher offers optimal protection of the thyroid against exposure to radioactive iodine in infants and that, when used during 10 days, it leaves the thyroid unaffected.

Animal cognition: an introduction to modern comparative psychology

Preface 1. Origins and Development of the Study of Animal Cognition The Darwinian Heritage and Nineteenth-Century Psychology The Behaviorist Break The Emergence of the Cognitive Approach The Modern Concepts of Representation and Memory The Study of Representation in Animals Problems Posed by the Study of Cognition in Animals 2. Laboratory Methods for Assessing Representation in Animals Learning Sets Mastery of Relations between Stimuli Category Formation Serial Learning as Evidence of Nonverbal Thought Mental Images in Animals Summary and Current Debate 3. Piagetian Studies in Animal Psychology Developmental Psychology and Comparative Psychology The Development of Intelligence Sensorimotor Activities in Animals Concrete Operations in Animals Summary and Current Debate 4. Tool Use and Spatial and Temporal Representations Tool Use Spatial Representations Temporal Representations Summary and Current Debate 5. Social Cognition Experimental Methods for the Study of Social Cognition Social Cognition in Monkeys Social versus Nonsocial Cognition Suggestions for Future Research Summary and Current Debate 6. Animal Communication and Human Language Comparisons of Animal and Human Communication Language-Trained Animals Differences in the Use of Signs by Apes and Children Pre-Linguistic Communication in Human Infants and Chimpanzee Infants Summary and Current Debate 7. Imitation, Self-Recognition, and the Theory of Mind Is There Evidence for Imitation in Animals? The Attribution of Mental States in Animals Self-Knowledge and Self-Recognition Relationships between Mirror Recognition, Social Attribution, Imitation, and Teaching Summary and Current Debate 8. An Agenda for Comparative Cognitive Studies Cognitive Ethology: Mental Representations or Mental Experiences? The Generalist versus Ecological Approach to Animal Cognition Conclusions References Index

Safety and immunogenicity of intramuscular and intravaginal delivery of HIV‐1 DNA constructs to infant chimpanzees

Any global strategy for controlling the human immunodeficiency virus (HIV) epidemic is likely to rely heavily on immunization of infants and children. Given the well-documented differences in children's responses to traditional vaccines, we initiated this study to extend our findings on DNA vaccination of adult chimpanzees to immunologically immature infant chimpanzees. Our findings were consistent with our previous work in adults as we observed that the DNA vaccines used here were both well tolerated and immunogenic within weeks of the initial vaccination.

Development of stone tool use by wild chimpanzees (Pan troglodytes).

At the age of 3.5 years, wild chimpanzees at Bossou, Guinea, begin to use hammer and anvil stones to crack oil-palm nuts to get the kernels. To clarify the developmental processes, the authors did a field experiment in which stones and oil-palm nuts were provided. Infant chimpanzees' stone-nut manipulation was observed and video recorded. Data were collected from 3 infants younger than 4 years old from 1992 to 1995. The authors analyzed 692 episodes of infants' stone-nut manipulation and 150 episodes of infants' observation of nut cracking performed by adults. Infants observed other chimpanzees' nut cracking and got the kernels from them. The stone-nut manipulation developed from a single action on a single object to multiple actions on multiple objects. Although infant chimpanzees at the age of 2.5 years already acquired basic actions necessary for nut cracking, they did not combine the actions in an appropriate sequence to perform actual nut cracking.

The Influence of Siblings On Wild Infant Chimpanzee Social Interaction

Abstract The presence or absence of older siblings influenced the social interactions of 17 wild infant chimpanzees between the ages of 6 and 24 months living at the Gombe National Park, Tanzania. The total amount of time spent in social interaction (contact, grooming and play) was similar for infants with and without siblings, as was the overall level of social interaction with the mother. However, subjects with siblings spent more time with their siblings, while subjects with no siblings interacted with other group members. These results indicate a possible set-point for infant chimpanzee social interaction. Developmental changes were also similar in both groups, but the infants with siblings had lower levels of interaction with the mother and higher levels of interaction with other group members during the age period of 12-18 months. The levels of social behaviors were not related to the sex of the infant.

Food transfer between mother and infant chimpanzees of the Mahale Mountains National Park, Tanzania

We studied food transfer between chimpanzee mothers and infants in the Mahale Mountains National Park, Tanzania. The rate of infant solicitation for food dramatically increased in the second year of life, then gradually decreased and, in the seventh year, virtually disappeared. The pattern of the ontogeny of food sharing precisely followed that of solicitation because mothers shared food only when requested to do so by their infants. The success rate of solicitation, however, did not display extreme changes across ages. Food that was difficult to process was shared more frequently because it was more likely to be demanded by infants. We defined food retrieval as an infant’s recovery of leftovers discarded by its mother. Food types retrieved were often those that are difficult to process and were also likely to be shared by mothers. However, infants tended to solicit small, difficult food types for sharing while they often retrieved the remains of large, difficult food types. The function of food sharing and food retrieval lies in an infant’s learning food types that it cannot easily obtain or process by itself. The level of competition for food between mothers and infants remained low throughout infancy. We noted no particular characteristic about foods from which infants were displaced by mothers. As infants grew older, they increased the distance between themselves and mothers that became more aggressive.

Manual action in infant chimpanzees: a preliminary study.

In human infants, index finger extension is shown frequently even from 3 months old, and it is considered that such pointing develops into deictic and communicative pointing however, there are many reports that chimpanzees do not point with the index finger. In the present study the manual actions of two infant chimpanzees were observed when the experimenter was trying to make eye contact with them. The result shows that pointing was shown very rarely by these infant chimpanzees even morphologically.

Imitation of facial gestures by an infant chimpanzee

A nursery-reared infant chimpanzee (Pan troglodytes) was tested for the ability to imitate human facial gestures, following the procedure ofMeltzoff andMoore (1977). The subject was observed between 5 to 15 weeks of ages. The results showed that the subject could imitate tongue protrusion in the age of 5–10 weeks and mouth opening between the ages of 5–11 weeks. However, from 12 to 15 weeks, the infant did not imitate the facial gestures. The present study clearly demonstrated that the infant chimpanzee could imitate human facial gestures in a particular period.

Centre of gravity of the body during the ontogeny of chimpanzee bipedal walking.

Bipedal walking was studied in chimpanzees between 1 and 19 years of age by measuring the external energy generated by the movement of the centre of gravity of the body. The 'recovery' of external energy in infant chimpanzees less than five years of age is smaller than in juveniles from 5 to 19 years of age. During the single stance phase, the short, flexed hindlimb of chimpanzees younger than 5 years is not able to lift the body centre of gravity high enough, so that these infants have a considerable energy output during bipedal walking. Extension of the hindlimb is one of the bases for energy economy in human bipedalism. The development of this low-energy-cost mechanism is an important component of the evolution of human bipedalism.

Developmental Processes of Nut-Cracking Skill among Infant Chimpanzees in the Wild.

Developmental Processes of Nut-Cracking Skill among Infant Chimpanzees in the Wild.

Appearance of ossification centers of the lower arm, wrist, lower leg, and ankle in immature orangutans and chimpanzees with an assessment of the relationship of ossification to dental development

This study examines the appearance of the secondary ossification centers in the lower arms, wrists, lower legs, and ankles of a cross-sectional sample of 20 infant orangutans and chimpanzees (15 of known age). The number of tarsal and carpal centers is analyzed relative to the degree of M1 development and the weight of individual animals. Variation in the appearance of these ossification centers is discussed relative to these variables and others. In addition, a sequence of appearance is established for the carpal and tarsal ossification centers in the orangutan and data is presented on the status of these centers in a fetal and newborn gorilla. Study results indicate that 1) there is variation in the number of secondary epiphyses present in animals of similar ages; 2) tarsal ossification is completed prior to carpal ossification in the orangutan; 3) there are indications of a relationship between weight and the number of ossification centers present in animals of similar age; and 4) there appears to be no evidence of specific relationships between carpal and tarsal development and M1 development. © 1996 Wiley-Liss, Inc.

Weight gain in captive chimpanzee infants: Comparisons by sex, rearing, and colony

Weight gain has been monitored for 13 years in a mixed longitudinal study of captive chimpanzee growth and development. This report presents results of a comparative analysis of weight relative to age in 175 animals during the first 24 months in four sex/rearing groups (hand-reared females, hand-reared males, mother-reared females, and mother-reared males) from three colonies with different physical, nutritional, and social environments (Primate Foundation of Arizona, University of Texas M.D. Anderson Cancer Center Department of Veterinary Resources, Bastrop, TX, and White Sands Research Center, Alamagordo, NM). The Lowess method is used to generate fits of weight vs. age for each group and colony, with which individual animals at these and other colonies may be compared for assessment of developmental status. Comparisons of the curves, using the jackknife approach, show that there are significant differences between the curves, indicating that rearing and environmental parameters may be factors in weight gain rate and must be considered in such an assessment. Rearing effects may be the dominant of these factors in weight gain. © 1996 Wiley-Liss, Inc.

Weight gain in captive chimpanzee infants: Comparisons by sex, rearing, and colony.

Weight gain has been monitored for 13 years in a mixed longitudinal study of captive chimpanzee growth and development. This report presents results of a comparative analysis of weight relative to age in 175 animals during the first 24 months in four sex/rearing groups (hand-reared females, hand-reared males, mother-reared females, and mother-reared males) from three colonies with different physical, nutritional, and social environments (Primate Foundation of Arizona, University of Texas M.D. Anderson Cancer Center Department of Veterinary Resources, Bastrop, TX, and White Sands Research Center, Alamagordo, NM). The Lowess method is used to generate fits of weight vs. age for each group and colony, with which individual animals at these and other colonies may be compared for assessment of developmental status. Comparisons of the curves, using the jackknife approach, show that there are significant differences between the curves, indicating that rearing and environmental parameters may be factors in weight gain rate and must be considered in such an assessment. Rearing effects may be the dominant of these factors in weight gain. © 1996 Wiley-Liss, Inc.

Weight gain in captive chimpanzee infants: Comparisons by sex, rearing, and colony

Weight gain in captive chimpanzee infants: Comparisons by sex, rearing, and colony

A profound disparity revisited: Perception and judgment of abstract identity relations by chimpanzees, human infants, and monkeys

We review the evidence for three important disparities involving the perception and judgment of identity relations by human and nonhuman primates. First, only humans beyond infancy and adult chimpanzees ( Pan troglodytes) with a history of language or token training can explicitly judge relations (same or different) between relations (identity and nonidentity) in a matching-to-sample (MTS) task. Second, both human and chimpanzee infants perceive relational similarity as measured in preference-for-novelty tasks. The human and chimpanzee infants, however, do not express this tacit knowledge in judgmental tasks like relational MTS. Third, unlike the human and chimpanzee infants, adult rhesus monkeys ( Macaca mulatta) tested with the same preference-for-novelty tasks do not perceive abstract relational similarities and differences despite their sensitivity to physical identity.

Asymmetries in spontaneous head orientation in infant chimpanzees (Pan troglodytes).

Asymmetries in spontaneous head orientation in infant chimpanzees (Pan troglodytes).

Development of visual acuity in infant chimpanzees

To assess development of visual acuity, a preferential looking procedure was administered to 13 nursery-reared chimpanzee infants ranging in age from 1 to 52 weeks. Chimpanzees exhibited acuity levels poorer than 1 cycle/degree when tested within the first weeks after birth, which is similar to that seen in neonatal humans and monkeys. Acuity improved about tenfold to near 10 cycles/degree during the first year. The time course of chimpanzee acuity development was more similar to that of humans than of monkeys. Tests were conducted at two or three separate viewing distances (38, 76, or 152 cm) in some individuals. This was done because previous observations during neurobehavioral assessments had found optimal focal distance to be longer in chimpanzee than in human infants. The results exhibited a nonsignificant trend for acuity to be better at far (76 or 152 cm) than at near (38 cm) viewing distances. These normative data can be usefully applied to further our understanding of the biological bases of perceptual and motor development and the effects of their coordination on subsequent development of other functions in primates.

Play behaviour and its effects on social development of common chimpanzees (Pan troglodytes)

The aim of the study was to monitor the social development of infant and juvenile common chimpanzees (Pan troglodytes) through their play behaviour at Taronga Zoo in Sydney in order to examine the possible effects of captivity (such as limited opportunities to play) on social development. Play behaviour was observed by focal animal sampling to determine individual differences, and their relationship to age, sex, and relatedness of the subjects. Analysis revealed marked individual variations in social, solitary, and object play behaviours indicative of a relatively well-balanced social and physical environment. Subjects showed a marked preference for play-partners of a different age compared to their own, and initiated interactions with similar frequency with members of both sexes. Many social-play dyads consisted of related individuals, and familiarity with prospective play-mates was the most decisive factor in social interactions.

Asymmetries in spontaneous head orientation in infant chimpanzees (Pan troglodytes).

Behavioral laterality in head orientation while sleeping in either a supine or prone posture was examined in 43 chimpanzees (Pan troglodytes) for the first 3 months of life. An overall significant right-side lateral bias was found for head orientation in the supine posture. A trend toward greater right-side bias in females compared with males was observed but failed to reach significance. These data suggest that asymmetries in head orientation are present early in life in chimpanzees, and they may be correlated with functional asymmetries observed in adulthood.

Ventricular septal defect in an infant chimpanzee (Pan troglodytes)

During clinical examinations and imaging studies of a prematurely born chimpanzee, a heart murmur, tachypnea, dyspnea, and disturbances of blood flow were observed. At necropsy, cardiomegaly, ventricular hypertrophy, and septal defects confirmed the presence of congenital VSD.