Development of visual preference for closely related species by infant and juvenile macaques with restricted social experience

Japanese and rhesus monkeys aged between 9 months old and 5 yrs old pressed a lever to see a variety of pictures of seven macaque species. These monkeys had various restricted social experience: namely, either reared by humans with conspecific or heterospecific peers, or cross-fostered between these two species. Rhesus monkeys tended to prefer seeing rhesus monkeys best among the pictures of the seven species without regard to their age or social experience. Japanese monkeys having restricted experience also liked to see rhesus monkeys better than Japanese monkeys, but not the best among the seven species. In a previous study, mother-reared infants of Japanese monkeys preferred seeing pictures of their own species over those of rhesus monkeys. These results suggest a dissociation of the determinants of this basic social preference: rhesus monkeys prefer to see their own species by nature while Japanese monkeys may learn to prefer their own species.     

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.     

Axial skeleton of Cebupithecia sarmientoi (Pitheciinae,Platyrrhini) from the middle miocene of La Venta,Colombia

The axial skeleton of Cebupithecia sarmientoi is described and analyzed for its functional and phylogenetic implications. The vertebrae of the holotype of C. sarmientoi (UCMP 38762) most closely resemble those of the extant pitheciine genus Pithecia and display features associated with adaptations for clinging and leaping as in that genus. Cebupithecia has a relatively long non-prehensile tail, which is most similar in absolute dimensions and proportions to Pithecia monachus. It also shares with P. monachus a distinctive morphology of the thoracic vertebrae, specifically the presence of a bony pillar spanning the vertebral lamina and body, caudal to the pedicle, herein designated the vinculum laminum. It is proposed that many of these features are shared primitive retentions from the last common ancestor of the Cebupithecia-pitheciine clade.     

New World Monkey Nightmares: Science,Art, Use,and Abuse (?) in Platyrrhine Taxonomic Nomenclature

The taxonomy and nomenclature of New World monkeys is becoming precariously unstable and impractical, plagued by revisions aimed at conforming to approaches that reject the Biological Species Concept for narrowly construed reasons and resulting in a hyperinflated taxonomy at species (often) and genus (sometimes) levels. This undermines a major goal of classification at the most basic taxonomic levels to ease communication and facilitate research. Since it is difficult to justify extensive changes in terminology without a deeply justified theoretical purpose or without showing what scientific benefits these alterations can bring, working primatologists need not accept this doctrinaire trend. Knowing as little as we do about what a species actually is, does not justify contorting the value of a species nomenclature so that it reflects nothing more than coat color, a node, or endpoint of a dendrogram. Am. J. Primatol. 74:692‐695, 2012. © 2012 Wiley Periodicals, Inc.     

Mutual dependencies between vocal and visual signals of squirrel monkeys

Visually recognizable social signals and structural call components, which had been demonstrated to be of social relevance within their own communication channel in previous experiments (disregarding or experimentally excluding other ones), were treated together, and their inter-dependencies analyzed when they were performed simultaneously in spontaneous behavior sequences of pairs of adult squirrel monkeys. It was found that: (1) all call classes were uttered within periods when either genital display or “triumph gesture” were shown; (2) production rates of particular vocal classes significantly deviated from no-display periods; (3) degree and direction of deviations (more/less frequent) were quite specific for both vocal and nonvocal classes (Figs. 1a & 1b); (4) differences depended also on which animal actually displayed (the vocalizing one, the other one, or both; Fig. 3); and (5) differences found for single animals when they played different roles in the experimental situation were smaller than those found between individuals, which could be related to dominance status (Table 2). The possibility of mutual modification of signals of different modalities and perspectives for future work are discussed.     

Fluctuating asymmetry in fetuses of diabetic rhesus macaques

This study examines dental fluctuating asymmetry (FA) in two samples of fetal rhesus monkeys, one composed of 19 fetuses from diabetic mothers (FDM) and the other of 20 fetuses from nondiabetic mothers. Seventeen measurements were taken on the deciduous dentition of right and left mandibles. The degree of FA was assessed by comparing FDM to fetuses of normal mothers by correlation between right and left sides, and analysis of variation differences between right and left sides. Significant FA was found for three traits based on the correlation between right and left sides and for seven traits by the between-treatment ratio of variance between sides. Distal teeth, both within and outside of a morphologic field, exhibit significantly greater FA than mesial teeth. Our results support the hypothesis that developmental instability is detectable by dental FA.     

Diurnal variations of androgens in sexually mature male Bolivian squirrel monkeys (Saimiri sciureus) during the breeding season

To assess diurnal fluctuations of serum androgens and cortisol in adult male Bolivian squirrel monkeys, these steroids were measured at predetermined times (0300, 0900, and 2300 hours) during two separate 24-hour periods in the breeding season (January 1983 and late November 1983). A significant diurnal change in serum cortisol was noted, with a nadir of 99.9 ± 11.9 μg/dl (x? ± SEM) at 2300 hours and a peak of 168.9 ± 7.8 μg/dl at 0900 hours. Conversely, a nadir in serum testosterone was noted at 0900 hours (117 ± 26.5 ng/ml) increasing to a peak of 328.5 ± 57.9 ng/ml at 0300 hours. Serum androstenedione and dehydroepiandrosterone followed a pattern similar to testosterone, with a serum androstenedione (176.4 ± 34.9 ng/ml) and dehydroepiandrosterone (11.7 + 1.8 ng/ml) nadir at 0900 hours and a plasma androstenedione (494.5 ± 55.4 ng/ml) and dehydroepiandrosterone (32.5 ± 4.1 ng/ml) peak at 0300 hours. Parallel changes of testosterone, androstenedione, and dehydroepiandrosterone suggest a significant contribution of all three androgens from a common site, the testes. In contrast to old world primates and humans, serum androstenedione levels exceeded serum testosterone levels in this species.