Somato-social development in the rhesus monkey following olfactory bulbectomy

Bilateral olfactory bulbectomy was performed on the rhesus macaque (M. mulatta) at 6 to 8 months of age. Social interaction and plasma testosterone levels obtained at approximately 2-1/2 years of age indicated that early olfactory bulb ablation resulted in higher levels of aggressivity concomitant with lower levels of social facilitory behavior. Bulbectomy did not interfere with the development of normal sexual posturing and orientation at the juvenile stage. Lower testosterone levels in the anosmic females indicated possible delay in the onset of puberty, while no differences were found in testosterone between the anosmic and control males. This investigation was supported by Behavioral Science Foundation, Los Angeles, California.     

Human-type ABO,MN, and Lewis blood groups,and Gm and Inv factors in several species of macaques

More than 1,000 blood samples were collected from macaques of speciesM. fuscata, M. cyclopis, M. irus, M. mulatta, M. nemestrina, andM. speciosa, and all or a part of them were tested for human-type ABO, MN, and Lewis blood groups, and Gm and Inv factors. Differences between and/or within species analogous to racial differences in man were markedly noted in the distribution of the ABO and Lewis blood groups. Saliva samples from a small number ofM. fuscata were tested quantitatively for the presence of H and Lewis substances, and it was found that almost all the animals were secretors of H, Le^a, and Le^b, independently of the Lewis blood groups of their red cells. Red cells of all macaques tested contained M or M-like, but not N^v(V), antigens, and no polymorphism of MN blood groups was present. Selected plasma samples fromM. fuscata, M. cyclopis, M. irus, andM. nemestrina were found to be negative for all Gm(1), Gm(2), Gm(4), and Inv(1) factors tested.This study was supported in part by the Japan Society for Promotion of Science Grant B-54 and by National Science Foundation Grant FJ 4.11. 1 as part of the Japan-U.S. Cooperative Science Program.     

Plasma testosterone and male dominance in a Japanese macaque (Macaca fuscata) troop compared with repeated measures of testosterone in laboratory males

Plasma testosterone levels measured by radioimmunoassay did not correlate with dominance rank or aggressive behavior in 21 adult males of a natural troop of Japanese macaques (Macaca fuscata). The data were replicated during two consecutive breeding seasons. Levels of male dominance and aggressive behavior were highly correlated from year to year, but testosterone levels of individual males were not. Nor were individual levels of testosterone correlated in five laboratory males sampled every 15 min over a 2-hr period. These laboratory males showed multiple, apparently random peaks but the mean testosterone level of 11.73 ng/ml did not vary significantly throughout the 120 min that were studied. By demonstrating that the stress of blood collection did not depress plasma testosterone titers in laboratory males, these data validated the method used in the study of the natural troop.     

Social relations in family-groups of wood miceApodemus sylvaticus under laboratory and enclosure conditions

Two family-groups of wood miceApodemus sylvaticus (Linnaeus, 1758) were observed: one in the laboratory (terrarium 100 × 60 × 60 cm) and the other under enclosure conditions (outdoor enclosure 200 × 100 × 100 cm). Three consecutive periods in the social relations of the family-groups were described: the linear hierarchy, the multidirectional social relations, and the variable dominance-subordination relations. The linear social hierarchy was reflected in the subordination behaviour of family members in relation to the dominant male, the father of the family. During the period of coexistence of a pair of parents with two litters of juveniles, both in the laboratory and under enclosure conditions, amicable relations between individuals occurred. Advanced forms of social care (paternal care, allomaternal lactation, transportation and licking by relatives) were also observed. In the laboratory, agonistic interactions were lacking during the linear hierarchy period, but the attainment of sexual maturity by individuals of the first two litters, accompanied by an increase in the number of mice, resulted in aggression between mature males and competition for dominance. Further, under increasingly crowded conditions, agonistic behaviour prevailed over other types of social interaction, and the survival rate of juveniles decreased. Under enclosure conditions a seasonal variation in agonistic interaction between mature individuals was recorded, similar to that observed in the wild. Despite the systematic increase in population density, no attacks by mature males on juveniles were observed.     

Testosterone levels among Aché hunter-gatherer men

Salivary testosterone levels were measured in a population of New World indigenous adult hunter-gatherer males in order to compare circulating levels of free unbound bioactive steroid with those previously reported among Boston and nonwestern males. The study population consisted of adult Aché hunter-gatherer males (n=45) living in eastern Paraguay. Morning and evening salivary testosterone levels (TsalA.M.; TsalP.M.) among the Aché were considerably lower than western values (Boston) and even lower than other previously reported nonwestern populations (Efe, Lese, Nepalese). No association was observed between height, weight, or age and salivary testosterone levels within the Aché group, although older men (ages>40) were poorly represented in the study sample. Nevertheless, a mild correlation was observed between Aché TsalA.M. levels and BMI (r=0.133,p=0.0725). Comparison of Aché values with those for other populations confirms the prevalence of significant interpopulational variation in testosterone levels among adult males. Interpopulational variation in male testosterone is not as great, however, as has been documented for ovarian steroids among females, nor is it likely that such variation reflects differences in male fecundity. Nevertheless, such interpopulational variation in salivary testosterone levels may have a functional significance in the regulation of protein anabolism in skeletal muscle, thereby affecting the overall energy budget of the organism. It is suggested that relative suppression of average testosterone may be adaptive under conditions of chronic energy shortage. This research was funded by the National Science Foundation, the Mellon Foundation, Sigma Xi, and Harvard University. The author is a doctoral candidate in biological anthropology at Harvard University. He received his B.A. in anthropology and psychology from UCLA in 1988 and his M.A. in anthropology from Harvard in 1994. His research interests include male reproductive ecology, male hormone function, foraging societies, evolutionary biology, and behavioral evolution.     

The influence of the food size,distance and food site on food carrying behavior in rats (Rattus norvegicus)

The behavior to foods in rats (Rattus norvegicus) was investigated in a seminatural enclosure and in a straight alley in the laboratory. In both situations, the size of food (0.045-, 1-, and 3-g pellets were used in the enclosure and 0.045-, 0.2-, 1-, and 3-g pellets in the alley) and distance between food sites and nest site (1.8, 3.6, 5.4, and 7.2 m in the enclosure and 2, 4, and 6 m in the alley) were varied. In both situations, when food was presented in only 1 place, the food carrying behavior increased as the size of food increased from 0.045 to 1-g. One and three g pellets were always carried, regardless of the distance to nest. On the other hand, when multiple food sites were presented in the alley, rats were more likely to carry small pellet from the further food site, whereas large pellet was always carried and were not influenced by the distance. The behavior to foods in the enclosure, however, was not influenced in either food site condition. This might be due to the difference in familiarity to the environment and anxiety from perceived predation risk.     

Social cues and hormone levels in male Octodon degus (Rodentia): a field test of the Challenge Hypothesis

Social interactions are important factors determining and regulating individual behaviors. Testosterone has been related to agonistic interactions, while glucocorticoids have been related to social stress, especially during interactions of dominance. We compared testosterone and cortisol concentrations in male degus (Octodon degus, Rodentia) under laboratory conditions without male social interactions, with data from wild males in nature. Under natural conditions, males should present higher levels of testosterone during the breeding season due to social interactions (Challenge Hypothesis). Alternatively, intense social instability could act as a stressing environment, raising glucocorticoids, which inhibit testosterone concentrations. Our results show a significant increase in agonistic interactions between males during the breeding season, and disappearance of non-agonistic male interactions during this period. Hormone levels in breeding season show nonsignificant differences between laboratory groups, but testosterone concentrations in field males were significantly higher than in laboratory males. Testosterone levels were similar among pre-breeding and breeding periods, but in field animals the concentration was approximately 30% higher than in laboratory degus. In field animals, we found two different mating strategies: resident males, with territorial behavior, and transient males, displayed an opportunistic approach to females. Finally, cortisol presents a similar pattern in both laboratory and field animals; pre-breeding values of cortisol are higher than during the breeding season. This suggests that social interactions in O. degus activate a rise in testosterone, supporting the Challenge Hypothesis, and could be considered as partial support of the Social Stress Hypothesis.     

Behavioral,physiological, and morphological components of dominance and mate attraction in male green iguanas

This study investigated the morphological, physiological, and behavioral components of social dominance important for mate attraction in male green iguanas (Iguana iguana). A group of 9 male and 11 female adult green iguanas was studied in a large semi-natural enclosure during one reproductive season (October–January). Four of the nine males never initiated aggressive encounters; the other five were observed to display aggressively toward each other and were ranked in a linear dominance hierarchy. Head size was the most important factor influencing fighting success. Head size and display frequency were positively correlated with plasma testosterone levels. Dominance rank directly influenced ability to monopolize areas containing resources used by females. The quality of a male's home range, measured as his access to a large basking rock in the enclosure, was related to the proportion of potential mates found within his home range. One male greatly surpassed the others in his ability to defend a home range of high quality and attract potential mates. These data suggest that physiological and morphological factors, through their influence on social behavior, may ultimately affect male reproductive fitness. © 1992 Wiley-Liss, Inc.     

Induction of sexual behavior in ovariectomized rhesus females with 19-hydroxytestosterone

Eight sexually experienced long-term ovariectomized female rhesus monkeys were given tests of sexual behavior following treatment with 19-hydroxytestosterone (19-OH-T, 1 mg/day for 13 days), and their performance was compared with that following treatment with estradiol benzoate (EB, 10 μg/day for 13 days). Each female was tested for 10 min with each of nine adult males. Blood samples were taken on the last day of treatment with EB, at the end of the intervening 3-month period of no treatment, and on the last day of treatment with 19-OH-T. Blood levels of testosterone and estradiol were quantified by radioimmunoassay. Mean rate of presenting at a distance (proceptive behavior) was significantly higher (P < 0.05) when they were treated with 19-OH-T, but the ratio of presents to male contacts (receptive behavior) was significantly higher (P <0.05) when they were treated with EB. All other components of female sexual behavior were the same. Males displayed fewer annoyance responses (rejecting jerk, P < 0.05) when the females were treated with 19-OH-T than when they were treated with EB. All other male responses occurred with the same frequencies under the two female treatment conditions. Injection of 19-OH-T and EB both resulted in plasma testosterone and estradiol levels higher than those found in the untreated condition. Testosterone levels did not differ under the two treatments (P > 0.05), but estradiol levels were higher under EB treatment than under 19-OH-T (P < 0.05). This study suggests that both testosterone and estradiol are essential for maximum sexual performance and that various components of sexual behavior may be differentially influenced by the ratio of testosterone to estradiol in plasma.     

A ten-month study of endogenous testosterone levels and behaviour in outdoor-living female rhesus monkeys (Macaca mulatta)

Endogenous testosterone levels were measured in association with sexual, aggressive, and social/affiliative behaviors in 11 outdoor-housed female rhesus monkeys over a ten-month period. Several behaviors (sex directed toward the male, sex received from the male, aggression directed toward the male, submission directed toward the male, submission directed toward the female, and groom another female) were significantly (p<0.05) positively correlated with testosterone in from one to five females. No trends were strong enough across all females to suggest that any of these correlations have species-wide significance. Factor analysis revealed clearcut clusters of behaviors, but elevations in testosterone were not strongly associated with any of these clusters. It is concluded that endogenous testosterone levels have little measurable effect on overt behavior in female rhesus monkeys.     

Seasonally of adult male japanese macaques (Macaca fuscata): Androgens and behavior in a confined troop

Seasonal variations in levels of serum testosterone, dihydrotestosterone (DHT), reproductive behavior, and social behavior were investigated in 12 adult males (5 to 20 + years of age) of the Oregon troop of Japanese macaques (Macaca fuscata). Blood samples were collected at 2- to 4-month intervals, and behaviors were monitored twice weekly over a 15-month period. Significant seasonal variations in levels of testosterone and DHT, and in frequencies of mount series, ejaculations, number of female partners, displays, courtship, and aggression were observed. Seasonal variations in reproductive and social behaviors did not correlate with seasonal variations in androgen levels because seasonal increases in these behaviors followed seasonal increases in the androgens with a 1- to 2-month delay. However, significant correlations between increased androgen levels and the onset of mating activity occur when mean monthly frequencies of mount series are shifted 1 to 2 months earlier to coincide with the rise in serum androgen levels. The frequency of adult male play and male-male mounting increased significantly when androgen levels were low. We suggest that photoperiod changes may function as a proximate cue in male Japanese macaques which induces a state of biological readiness for mating, and the behavioral consequences (i.e., mating) are then dependent upon the presence of receptive females.     

Testosterone related to age and life-history stages in male baboons and geladas

Despite significant advances in our knowledge of how testosterone mediates life-history trade-offs, this research has primarily focused on seasonal taxa. We know comparatively little about the relationship between testosterone and life-history stages for non-seasonally breeding species. Here we examine testosterone profiles across the life span of males from three non-seasonally breeding primates: yellow baboons (Papio cynocephalus or P. hamadryas cynocephalus), chacma baboons (Papio ursinus or P. h. ursinus), and geladas (Theropithecus gelada). First, we predict that testosterone profiles will track the reproductive profiles of each taxon across their respective breeding years. Second, we evaluate age-related changes in testosterone to determine whether several life-history transitions are associated with these changes. Subjects include males (> 2.5 years) from wild populations of each taxon from whom we had fecal samples for hormone determination. Although testosterone profiles across taxa were broadly similar, considerable variability was found in the timing of two major changes: (1) the attainment of adult levels of testosterone and (2) the decline in testosterone after the period of maximum production. Attainment of adult testosterone levels was delayed by 1 year in chacmas compared with yellows and geladas. With respect to the decline in testosterone, geladas and chacmas exhibited a significant drop after 3 years of maximum production, while yellows declined so gradually that no significant annual drop was ever detected. For both yellows and chacmas, increases in testosterone production preceded elevations in social dominance rank. We discuss these differences in the context of ecological and behavioral differences exhibited by these taxa.     

Factors affecting the behavior of captive white rhinoceros (Ceratotherium simum) and the accuracy of ad-hoc keeper data

Although white rhinoceros (Ceratotherium simum) are common in captivity, few behavioral studies have been conducted and there is seemingly no research for immersive exhibits where potential for visitor effects is high. Moreover, little information exists on possible effects of weather and temperature on rhino outside their native range. Here we analyze 14,501 observations of rhino in a drive-through enclosure. Data were collected by researchers (n = 12,160 datapoints) and keepers (n = 2341 datapoints) over a 4-month period. We aimed to: (1) quantify behavior using detailed researcher-collected data and contemporaneous but ad hoc keeper-collected data; (2) compare datasets statistically; (3) establish effects of visitors, temperature, and weather on behavior; and (4) assess the influence of visitors on similarity of researcher/keeper datasets. Activity budgets were similar to the wild and the single previous study from a traditional (nondrive-through) enclosure. There was some discrepancy in activity budgets between researcher and keeper data due to significant differences in recorded frequency of two rare behaviors (horn rub; social interaction) and two behaviors that could be easily confused (grazing vs. standing with head-down): recording of other behaviors matched well. Weather and temperature affected behavior, with rhino becoming more sedentary (−locomotion, grazing; +resting, standing, and sedentary eating of hay) on hot/sunny days compared to cool/wet days. The number of visitor vehicles had a fairly negligible effect but resting was lower on busy days, possibly as vigilance increased. The match between researcher/keeper datasets was lowest when visitor numbers were high, suggesting visitors might affect keeper ability to accurately record behavior.     

Androgens and male mating behavior in rough-skinned newts, Taricha granulosa

Cyproterone acetate was administered either orally or intraperitoneally to intact, adult male newts, Taricha granulosa. The number of males that exhibited the courtship behavior of clasping when tested with nuptial females was not altered by the antiandrogen treatments. In males which were unresponsive to nuptial females, the occurrence of clasping was not evoked by injections for 4 days of testosterone, dihydrotestosterone, or 11-ketotestosterone. Further, the incidence of clasping was not significantly elevated by injections of prolactin and/or testosterone for 30 days. The effect of sexual activity on testosterone and dihydrotestosterone levels in male newts was determined by radioimmunoassay of plasma collected from males which were: (1) isolated from females; (2) allowed to clasp a female for 2 min; or (3) allowed to clasp a female for 1 hr. The testosterone and dihydrotestosterone levels were unchanged during this period of clasping. In February and again in June, plasma androgen concentrations were measured in males which differed in their propensity to initiate courtship when paired with females. Androgen levels were similar for males that clasped a female and males that never attempted to clasp a female. Plasma androgen levels in the male newt are apparently not correlated with sexual responsiveness.     

A method for studying social and reproductive behaviour of subterranean rodents in captivity

A methodology for studying the social and reproductive behaviour of solitary subterranean rodents under laboratory conditions is proposed. A first account ofCtenomys talarum (Thomas, 1898) behaviour is also provided with the aim of evaluating the proposed methodology and to advance presently unknown information on its social behaviour and mating system. The device is a seminatural enclosure, departing from traditional test cages with respect to increased: (1) size, (2) structural complexity, (3) social complexity, and (4) resemblance to natural conditions. It consists of artificial burrows each comprising 3.5 m of tunnel, a resource cage and a nest box, resembling the structural complexity described forC. talarum burrows. Burrows are connected to a common space, which allows social interaction among various individuals. Animals were observed in the seminatural enclosure — 3 females and 2 males, in accordance with sex ratios found in natural populations — for a period of 6 months. We obtained data related to reproductive and social behaviour: marking, aggression, vocalization, courtship and copulation, pregnancy, pup development, and parental care. The proposed system enables the collection of behavioural data as yet unavailable due to the secretive habits and aggressiveness that characterize this group of rodents, coupled with the difficulties associated with simulating subterranean conditions.     

Aggressive behavior and change in salivary testosterone concentrations predict willingness to engage in a competitive task

The current study investigated relationships among aggressive behavior, change in salivary testosterone concentrations, and willingness to engage in a competitive task. Thirty-eight male participants provided saliva samples before and after performing the Point Subtraction Aggression Paradigm (a laboratory measure that provides opportunity for aggressive and defensive behavior while working for reward; all three involve pressing specific response keys). Baseline testosterone concentrations were not associated with aggressive responding. However, aggressive responding (but not point reward or point protection responding) predicted the pre- to post-PSAP change in testosterone: Those with the highest aggressive responding had the largest percent increase in testosterone concentrations. Together, aggressive responding and change in testosterone predicted willingness to compete following the PSAP. Controlling for aggression, men who showed a rise in testosterone were more likely to choose to compete again (p = 0.03) and controlling for testosterone change, men who showed the highest level of aggressive responding were more likely to choose the non-competitive task (p = 0.02). These results indicate that situation-specific aggressive behavior and testosterone responsiveness are functionally relevant predictors of future social behavior.     

Evaluation of Sesbania speciosa as a green manure for lowland rice in the dry zone,Sri Lanka

Sri Lankan rice farmers rarely practise green manuring and they depend mostly on chemical fertilizers for the nutrient requirement of their crops. With the removal of government subsidy on fertilizers since 1990, they are now faced with the dilemma of meeting the cost of production to sustain previous yield targets. Therefore the present study devotes to evaluate alternative cheaper nutrient sources like green manures for rice. Results of recent work in Sri Lanka have shown that Sesbania speciosa Taub. ex Engl. is a promising green manure for lowland rice in the dry zone. It was evaluated to adopt a suitable green manuring system for rice. Its year-round biomass production, nutrient accumulation during the vegetative growth and nitrogen fixation were monitored. Field trials were conducted to investigate its ability to suppress weed growth when grown during fallow periods and its contribution to soil fertility and effect on rice yield. Highest biomass of around 100 g dry matter per plant, was achieved when S. speciosa was seeded in August and harvested at flowering in November. When this was planted during a fallow period at a spacing of 0.25×0.25 m (16 plants m^-2), percentage weed reduction was as much as 40%. Its N₂ fixation activity was similar to that of S. sesban (L.) Merr., Nitrogen concentration in S. speciosa increased until 70 days after establishment and then decreased towards flowering. Phosphorus and K accumulation was also effective during this period. Therefore suitable time for soil-incorporation of S. speciosa is around 70 days after establishment. S. speciosa-manured and chemically fertilized rice crops were comparable in terms of grain yield, indicating the effective nutrient supplying potential of this green manure. Straw biomass was significantly high under S. speciosa, because of the high N-allocation to vegetative growth of rice under this. This evaluation shows that S. speciosa not only supplies N, but is also an effective and complete supplier of other nutrients for rice. A scheme to introduce this into rice production system is proposed, where S. speciosa is seeded/broadcast two weeks before crop harvest (around January) in Maha (major) season as well as Yala (minor) season (around June) so that its biomass can be incorporated into soil during land preparation of subsequent seasons.     

Variables that influence the activity of captive orangutans

It is well known that the environment significantly influences the behavior of captive animals. However, the specific nature of the cues that promote speciestypical behavior patterns is not usually known. This study extends an earlier investigation by Wilson (Zoo Biology 1: 201–209, 1982). The objective was to identify and quantify specific environmental components that influence activity levels in orangutans. Six enclosure variables were quantified, and activity levels measured, for 29 orangutans housed in nine zoological parks. Multiple regression analysis indicated that the combination of the number of animals, amount of usable surface area, number of movable objects, and enclosure volume was the best predictor of activity levels, accounting for 58% of the variance in activity levels. It was concluded that the provision of large enclosures, containing large numbers of movable objects and providing social opportunities, would promote higher levels of activity in captive orangutans. © 1992 Wiley-Liss, Inc.     

Sex difference in the relationship between the hypothalamic-pituitary-adrenal axis and sex hormones in obesity

Objective: This study was carried out to investigate the role of sex in the regulation of the hypothalamic‐pituitary‐adrenal (HPA) axis and its relationship with testosterone levels in male and female obesity. Research Methods and Procedures: Twenty‐two obese men (OB‐M) and 29 obese women (OB‐W) participated in the study. Two groups of normal weight men (NW‐M) and women (NW‐W), respectively, served as controls. In basal conditions, blood concentrations of major androgens, sex hormone—binding protein, and gonadotropins were assessed, and the free androgen index (testosterone ×100/ sex hormone‐binding globulin) was calculated. All subjects underwent a combined corticotropin‐releasing hormone plus arginine‐vasopressin stimulation test. Results: OB‐M and NW‐M had higher basal adrenal cortical tropic hormone (ACTH) and cortisol levels than their female counterparts. In addition, ACTH, but not cortisol basal, levels were significantly higher in obese than in normal weight controls in both sexes. OB‐W had a higher response than OB‐M to the combined corticotropin‐releasing hormone plus arginine‐vasopressin test of both ACTH and cortisol [expressed as incremental percentage of area under the curve (AUC%)]. The same finding was present between NW‐W and NW‐M. Basal luteinizing hormone levels were negatively correlated to ACTH_AUC% in both OB‐W and OB‐M. In the OB‐W, however, a positive correlation was found between cortisol_AUC% and testosterone (r = 0.48; p = 0.002), whereas a tendency toward a negative correlation was present in OB‐M. Discussion: In conclusion, we have shown a significant positive relationship between the activity of the HPA axis and testosterone in obese women, which suggests a partial responsibility of increased HPA axis activity in determining testosterone levels. In addition, it clearly seems that, as reported in normal weight subjects, a sex difference in the HPA axis activity still persists even in the presence of obesity.     

Aspects of interspecific interaction betweenReithrodontomys megalotis andMicrotus montanus in one acre enclosures

1. Two one acre enclosures were cleared of all resident rodents, and then, one enclosure was seeded with founder populations of Reithrodontomys megalotis (grid M) and the other with Reithrodontomys megalotis plus Microtus montanus (grid I). Founder populations consisted of eight animals for each species introduced and a sex ratio of 1∶1.
2. Five parameters were measured for a period of one year. Data collection was started in September 1971, and ended in September 1972; enumeration was conducted twice a month for three days.
3. The five parameters measured were: (1) population density through time and individual growth rates; (2) reproduction; (3) survival of age and sex classes; (4) sex ratio; and (5) sizes of home ranges.
4. There were no significant differences in three out of the five parameters studied. Density estimates along with individual growth rates were not significantly different between the grids. Reproduction, including breeding season and efficiency of reproductive effort, showed no or very little variation due to interspecific interaction. Home range sizes did not appear to be significantly different between the grids. Survival of juvenile males on grid I seemed lower and juvenile males from grid I were significantly smaller although possibly younger than those of grid M. The sex ratio of grid I was significantly different from the expected 1∶1 ratio.
5. It is postulated that Reithrodontomys megalotis may regulate their density by alteration of their sex ratios.