Chimpanzees (Pan troglodytes) Are Predominantly Right-Handed: Replication in Three Populations of Apes.

Population-level right-handedness has historically been considered a hallmark of human evolution. Even though recent studies in chimpanzees (Pan troglodytes) have demonstrated population-level right-handedness for certain behaviors, some have questioned the validity and consistency of these findings by arguing that reported laterality effects are specific to certain colonies of apes and to those chimpanzees reared by humans. The authors report evidence of population-level right-handedness in 3 separate colonies of chimpanzees. Moreover, handedness in the 3 colonies was unrelated to the proportion of subjects that were raised by humans. This is the strongest evidence to date that population-level handedness is evident in chimpanzees and is not an artifact of human rearing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative assessment of handedness for a coordinated bimanual task in chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus).

Hand preferences for a coordinated bimanual task were assessed in a sample of 31 captive gorillas (Gorilla gorilla) and 19 captive orangutans (Pongo pygmaeus) and were compared with chimpanzee (Pan Troglodytes) hand preferences in subjects that were matched on the basis of age, sex, and rearing history. The task required that the apes remove food from the inside edges of a symmetrical polyvinyl chloride pipe presented to them in their home cages. The results indicate significant species differences with chimpanzees showing population-level right-handedness and orangutans showing population-level left-handedness. The gorillas showed a nonsignificant trend toward right-handedness. The results are discussed in terms of possible ecological or biomechanical factors that may influence hand preferences in different ape species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Primary motor cortex asymmetry is correlated with handedness in capuchin monkeys (cebus apella).

Humans exhibit a population-wide tendency toward right-handedness, and structural asymmetries of the primary motor cortex are associated with hand preference. Reported are similar asymmetries correlated with hand preference in a New World monkey (Cebus apella) that does not display population-level handedness. Asymmetry of central sulcus depth is significantly different between left-handed and right-handed individuals as determined by a coordinated bimanual task. Left-handed individuals have a deeper central sulcus in the contralateral hemisphere; right-handed individuals have a more symmetrical central sulcus depth. Cerebral hemispheric specialization for hand preference is not uniquely human and may be more common among primates in general. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of posture on hand preference during experimental food reaching in bonobos (Pan paniscus).

The effect of posture on hand preferences was examined in an experiment with 5 bonobos (Pan paniscus). To obtain a food reward, the animals had to adopt 1 out of 7 different postures. These postures represented an increasing problem to the maintenance of body equilibrium. It was expected that an increasing demand for equilibrium maintenance would elicit individual preferences and a population-level bias. All animals showed an increasing trend toward left-handedness while shifting to a bipedal posture from a seated posture by way of a quadrupedal posture. The importance of bipedalism in the evolution of left- and right-handedness is discussed briefly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The use of bouts and frequencies in the evaluation of hand preferences for a coordinated bimanual task in chimpanzees (Pan troglodytes): An empirical study comparing two different indices of laterality.

Hand preferences for a coordinated bimanual task were assessed in 109 chimpanzees (Pan troglodytes). Hand preference was evaluated for 4 test sessions using bouts and frequencies of hand use to compare the sensitivity of each level of analysis in evaluating individual variation in handedness. Overall, significant population-level right-handedness was found using several different measures of hand use. Handedness indices based on bouts and frequencies were highly and significantly correlated. Moreover, hand preferences were consistent across tests despite efforts to situationally bias preference during each test. Taken together, these data do not support the view that bouts are a better level of analysis for evaluating hand preference. The results further suggest that hand preferences for coordinated bimanual actions are not influenced by situational factors and may reflect an inherent specialization of the left hemisphere for motor skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glomerular endothelial dysfunction determines disease progression: a hypothesis

A captive colony of baboons has been used for three decades for various reproductive studies where application of findings to human therapeutics was desired. The characteristics of the menstrual cycle in baboons are very similar to those of women, except that of the baboon is slightly longer and there is a lower luteal phase concentration of oestradiol. The duration of pregnancy in baboons is about two-thirds that of humans but patterns of oestrogen and progesterone secretion are virtually identical. The principal oestrogen produced by the pregnant baboon is oestrone, while oestriol is the most abundant in human pregnancies. Chorionic gonadotrophin (CG) is elevated significantly only in the first trimester of a baboon pregnancy, while human pregnancy concentrations of this hormone are about one-third of the first trimester level in the second and third trimesters. Breeding success of baboons in captivity depends on care being taken to cull infertile animals from the colony prior to commencing matings. Under optimal conditions, fertility rates can reach nearly 80%. Female baboons have been successfully used to gain insights into antifertility effects of contraceptive vaccines directed against CG, spermatozoa and ovum antigens. Extensive use of the colony for developing a human chorionic gonadotrophin (HCG) antifertility vaccine has been invaluable for progress in this field. Other pharmaceuticals and devices have been successfully tested in baboons, but costs and mandated regulations for the management of these nonhuman primates have made their current use in meaningful studies extremely difficult.     

Birth order and hand preference in chimpanzees (Pan troglodytes): Implications for pathological models of handedness in humans.

The effect of birth order on hand preference was assessed in a sample of 154 captive-born chimpanzees. Subjects were classified as first, middle, or latter born using 2 classification criteria based on their birth order. Hand preference was measured using a task that elicited coordinated bimanual actions. Significant birth-order effects were found for both classification criteria, with first- and latter-born subjects exhibiting a lesser degree of right-handedness compared with middle-born subjects. These data suggest that biological rather than sociological factors play a greater role in explaining the observed birth-order effects on hand preference in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Linkage mapping in Papio baboons: conservation of a syntenic group of six markers on human chromosome 1

We have established multipoint genetic linkage among six loci in baboons (Papio hamadryas). Published PCR primers designed to amplify five human microsatellite loci were used to amplify homologous loci in 229 pedigreed baboons. Southern blotting was used to type two RFLPs in a functional gene (anti-thrombin III) in a subset of those animals. All six loci are known to map to human chromosome 1q, a region of the genome predicted by karyotype studies to be conserved in baboons. Pairwise recombination frequencies and lod scores indicate that the six loci are also linked in baboons. Recombination distances among the loci are similar to those reported for humans. Like humans, the baboons exhibit higher rates of recombination in females than in males. This study demonstrates that (1) microsatellite loci first described and characterized in the human genome can be effectively used for genetic linkage mapping in non-human primates, (2) a group of genetic loci known to be linked on human chromosome 1q are also linked in the baboon genome, and (3) sex differences in recombination frequencies among loci on human chromosome 1q are also observed in the genome of this Old World monkey. This constitutes the first reported multipoint linkage map in any nonhuman primate.     

Evidence for the pathological right-handedness hypothesis.

The present study investigated handedness of 109 Korean patients with temporal lobe epilepsy (TLE) and 120 normal control participants. Left TLE was associated with a significantly raised incidence of left-handers relative to normal controls. More important for the present purpose, right TLE was associated with a significantly raised incidence of strong right-handers relative to normal controls. This finding indicates that certain early damage to the right brain causes a mild hypofunction of the left hand in natural weak right-handers, which in turn causes the patient to switch to strong right-handedness. To the authors' knowledge, this finding provides the 1st empirical evidence supporting the pathological right-handedness hypothesis. Prior failure to find evidence of pathological right-handedness may reflect the low base rate of natural left-handers rather than true absence of pathological right-handers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of combinatorial manipulation in infant baboons (Papio cynocephalus anubis).

Infant baboons housed in individual cages combined objects and used tools in play and food acquisition. The baboons first combined objects at age 2 mo, placed objects inside a container at age 4 mo, and repeatedly used paper towels as sponges at age 6 mo. The results of this investigation demonstrate that infant baboons develop extensive manipulative propensities during the 1st postnatal semester. These data are consistent with hypotheses that (1) creative recombination facilitates the acquisition of novel behavior patterns, and (2) the development of combinatorial manipulation in baboons parallels the development of analogous abilities in human infants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Video-task assessment of stimulus novelty effects on hemispheric lateralization in baboons (Papio papio).

In a video matching-to-sample task, we examined the effects of stimulus novelty on hemispheric specialization in 6 baboons (Papio papio). After familiarization with a set of 8 composite stimuli, baboons were tested with either familiar stimuli paired in a novel way, novel stimuli composed of familiar elements, or novel stimuli differing in structure from the previous stimuli. Analyses focused on visual field differences between initial and later trials in each condition. The findings reflected shorter left than right visual half-field response times for initial but not for terminal trials. With regard to accuracy, scores were smaller for the initial trials than for the later ones, but there was no significant difference between left and right visual half-fields. Overall, this study suggests that hemispheric lateralization changes with practice and that the right hemisphere of the baboon plays a critical role in the processing of novelty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetries in the Hippocampus and Amygdala of Chimpanzees (Pan troglodytes).

Magnetic resonance imaging was used to measure the hippocampal and amygdalar volumes of 60 chimpanzees (Pan troglodytes). An asymmetry quotient (AQ) was then used to calculate the asymmetry for each of the structures. A one-sample t test indicated that there was a population-level right hemisphere asymmetry for the hippocampus. There was no significant population-level asymmetry for the amygdala. An analysis of variance using sex and rearing history as between-group variables showed no significant main effects or interaction effects on the AQ scores; however, males were more strongly lateralized than females. Several of these findings are consistent with results found in the human literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing of contour closure by baboons (Papio papio).

This study investigated the Gestalt law of closure in baboons. Using a computer-controlled self-testing procedure, we trained baboons (Papio papio) to discriminate open versus closed shapes presented on a touch screen with a two-alternative forced choice procedure. Ten baboons (OPEN + group) were trained with the open shapes serving as the positive stimulus (S+), and nine others (CLOSE + group) were trained with the closed shape serving as S+. The OPEN + group obtained higher discrimination performance than the CLOSE + group (Exp 1), but its scores declined when new line segments were added to the stimuli (Exp 2) and after smoothing the end points of the open shapes (Exp 3). The CLOSE + group was less affected by the above manipulations of local stimulus dimension, but its performance was disrupted when the collinearity end points was reduced (Exp 3). Use of a visual search task revealed that the search for an open shape among closed distractors was less attention demanding in baboons than the search for a closed shape among open ones (Exp 4). It is concluded that (1) end lines rather than closeness per se are perceptual primitives for the open versus closed discrimination in baboons, and (2) the relative emphasis on local or configural cues when processing contour closure depends on experiential factors in baboons and is thus subject to interindividual variations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Comparison of grouping abilities in humans (Homo sapiens) and baboons (Papio papio) with the Ebbinghaus illusion.

This research comparatively assessed grouping mechanisms of humans (n = 8) and baboons (n = 8) in an illusory task that employs configurations of target and surrounding circles arranged to induce the Ebbinghaus (Titchener) illusion. Analyses of response behaviors and points of subjective equality demonstrated that only humans misjudged the central target size under the influence of the Ebbinghaus illusion, whereas baboons expressed a more veridical perception of target sizes. It is argued that humans adopted a global mode of stimulus processing of the illusory figure in our task that has favored the illusion. By contrast, a strong local mode of stimulus processing with attention restricted to the target must have prevented illusory effects in baboons. These findings suggest that monkeys and humans have evolved modes of object recognition that do not similarly rely on the same gestalt principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pharmacokinetics, immunogenicity, and efficacy of dimeric TNFR binding proteins in healthy and bacteremic baboon

Immunogenicity, pharmacokinetics, and therapeutic efficacy of three novel dimeric soluble tumor necrosis factor (TNF)-receptor I constructs [TNF-binding protein (bp)] were evaluated in 28 baboons, 12 of which were healthy and 16 were challenged with a lethal Escherichia coli bacteremia. The three constructs differed only in the number of extracellular domains of the TNF receptor I and were dimerized with polyethylene glycol. Although all three constructs had generally similar pharmacokinetics when administered to a naive animal, they differed quantitatively in their immunogenicity. Antibodies were detected more frequently, and titers were significantly higher (P < 0.05) in both healthy and septic baboons that received the 4.0-domain TNF-bp construct, compared with animals receiving the 2.6-domain construct. When the TNF-bp constructs were administered a second time (21 days later), the half-lives of the three constructs were significantly shorter in animals that had an antibody response after the first injection. In contrast, all three TNF-bp constructs were equally effective at improving outcome, blocking a systemic TNF-alpha response, and attenuating the cytokine responses when administered at a dose of 1.0 mg/kg body wt 1 h before a lethal E. coli infusion. The findings suggest that immunogenicity of TNF-bp constructs can be altered by changing the number of functional domains, without affecting their capacity to neutralize TNF-alpha and to abrogate TNF-mediated pathology.     

Effects of acute and chronic exposure to nicotine aerosol on bronchial reactivity to inhaled methacholine

Normal baboons, like humans, demonstrate a wide range of bronchial reactivity to inhaled methacholine. Cigarette-smoking baboons demonstrate reduced bronchial reactivity to inhaled methacholine compared with sham-smoking controls after 6 pack-yr of smoking. To evaluate the role of nicotine in this blunting of airway reactivity, we studied the effects of both acute and chronic nicotine inhalation on reactivity to methacholine in baboons. Inhalation of 2 mg of nicotine had no acute effect on lung function but blunted bronchial reactivity in highly reactive animals. This effect was not diminished after daily inhalation of nicotine for 90 days. Marked interindividual differences in bronchial reactivity to methacholine were not abolished by propranolol, suggesting that factors other than beta-adrenergic tone account for this intersubject variability.     

Anti-P-selectin antibody decreases inflammation and thrombus formation in venous thrombosis

PURPOSE: Venous thrombosis and inflammation are interrelated. P-selectin contributes to activation of leukocyte-mediated inflammation. Therefore, we hypothesized that the neutralization of P-selectin would decrease vein wall inflammation and thrombosis. METHODS: Twelve baboons underwent infrarenal inferior vena caval balloon occlusion to induce thrombosis. Two groups of four baboons received neutralizing intravenous anti-P-selectin antibody (PSab) GA6 or CY1748 before occlusion and at days 2 and 4. Four baboons received saline control injections. One baboon per group was killed at days 2, 6, and 13, and at 2 months. Analysis included phlebography, ultrasound, gadolinium (Gd)-enhanced magnetic resonance venography (reflecting vein wall inflammation), and histologic, morphometric, and protein evaluation of the vein wall. Thrombus presence or absence was assessed. RESULTS: By day 2 in PSab baboons, vein wall Gd enhancement was decreased in the mid-inferior vena cava and the right iliac vein (p < 0.05; GA6 vs control baboons), normalizing by 2 months. The mid-inferior vena cava revealed fewer neutrophils and total leukocytes in PSab baboons; however, for GA6 in the right iliac vein these decreases were not present despite the absence of Gd enhancement; they were decreased with CY1748. PSab baboons demonstrated significantly less thrombus than control baboons (p < 0.01, GA6 and CY1748 vs control baboons). CONCLUSIONS: Anti-P-selectin antibody decreases vein wall inflammation and thrombus formation. Inhibition of P-selectin may be useful in venous thrombosis prophylaxis.     

Infants communicate in order to be understood.

Infants intentionally communicate with others from before their 1st birthday. But there is some question about how they understand the communicative process. Do they understand that for their request to work the recipient must both understand the request and be cooperatively disposed to fulfill it? On the basis of the study by Shwe and Markman (1997), we developed a new paradigm that tested whether and how 18-, 24-, and 30-month-old children repair a failed request. Children at all ages repaired their requests in the case of a misunderstanding even if they had obtained the requested object already. They also repaired differently depending on the precise reason for the communicative failure (e.g., misunderstanding the referent versus the communicative intent) and did not repair in the case of correct understanding, even if they did not get the requested object. Thus, from very early in their communicative careers, young children operate with a basic understanding of the mental and cooperative nature of human communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Superinfection with human immunodeficiency virus type 2 can reactivate virus production in baboons but is contained by a CD8 T cell antiviral response

An animal model was used to assess whether resistance to superinfection by human immunodeficiency virus (HIV) can exist in vivo. Asymptomatic baboons (Papio cynocephalus), previously infected with HIV-2, were first challenged with homologous virus (HIV-2UC2 or HIV-2UC14) and later with heterologous virus (HIV-2UC12). After both virus inoculations, either resistance to viral infection or a transient viremia was observed. The original virus was recovered in 3 baboons, suggesting that reactivation of a latent infection occurred on heterologous challenge and that HIV-2 superinfection is blocked by processes established during prior infection. Antibody titers measured by ELISA and virus neutralization remained at low levels. However, suppression of HIV-1 replication was observed with CD8 T cells and filtered cell culture supernatants. The soluble factor involved was not a beta-chemokine. This resistance to HIV superinfection appears to be mediated at least in part by CD8 T cells that suppress virus production.