Role Behavior of an Agonadal Alpha-Male Rhesus Monkey in a Heterosexual Group

Bernstein, Irwin S.; Gordon, Thomas P.; Peterson, Mary S.

doi:10.1159/000155918

Cited by 11 publications

(1 citation statement)

References 5 publications

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“…However, other studies failed to find a correlation between dominance ranking and fecal testosterone levels (Barrett, Shimizu, Bardi, & Mori, 2002). And in at least one study, an agonadal adult male rhesus macaque rose in social dominance after placement in several different heterosexual colonies, becoming the alpha male on multiple occasions and exhibiting typical age- and status-specific sexual and social behavior (Bernstein, Gordon, & Peterson, 1979), which suggests that other factors apart from circulating gonadal hormones also influence social rank such as maternal social status (e.g., Dixon & Nevison, 1997).…”

Section: Discussionmentioning

confidence: 99%

Gonadectomy negatively impacts social behavior of adolescent male primates

Richards¹,

Morris²,

Ward³

et al. 2009

Hormones and Behavior

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Social behavior changes dramatically during primate adolescence. However, the extent to which testosterone and other gonadal hormones are necessary for adolescent social behavioral development is unknown. In this study, we determined that gonadectomy significantly impairs social dominance in naturalistic settings and changes reactions to social stimuli in experimental settings. Rhesus macaques were castrated (n = 6) or sham operated (n = 6) at age 2.4 years, group-housed for 2 years, and ethograms were collected weekly. During adolescence the gonadally intact monkeys displayed a decrease in subordinate behaviors and an increase in dominant behaviors, which ultimately related to a rise in social status and rank in the dominance hierarchy. We measured monkey's reactions to emotional faces (fear, threat, neutral) of conspecifics of three ages (adult, peer, infant). Intact monkeys were faster to retrieve a treat in front of a threatening or infant face, while castrated monkeys did not show a differential response to different emotional faces or ages. No group difference in reaction to an innate fear-eliciting object (snake) was found. Approach and proximity responses to familiar versus unfamiliar conspecifics were tested, and intact monkeys spent more time proximal to a novel conspecific as compared to castrates who tended to spend more time with a familiar conspecific. No group differences in time spent with novel or familiar objects were found. Thus, gonadectomy resulted in the emergence of significantly different responses to social stimuli, but not non-social stimuli. Our work suggests that intact gonads, which are needed to produce adolescent increases in circulating testosterone, impact social behavior during adolescences in primates.

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Section: Discussionmentioning

confidence: 99%

Gonadectomy negatively impacts social behavior of adolescent male primates

Richards¹,

Morris²,

Ward³

et al. 2009

Hormones and Behavior

View full text Add to dashboard Cite

show abstract

Social factors modulate the effects of hormones on the sexual and aggressive behavior of macaques

Zumpe

Michael

1996

American J Primatol

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We previously reviewed the effects of gonadal hormones on the sexual and aggressive behavior of macaques as observed in field, outdoor colony, and laboratory studies. There were consistent similarities between findings from different observational settings, but there were also noteworthy differences which suggested the importance of social and environmental factors in modulating the effects of hormones. We now examine the role of these factors further and consider the extent to which partner preferences, familiarity between individuals, and also dominance rank can affect the behavior of male‐female pairs and thereby modify the influences of hormones. The evidence suggests that all these factors are important. Hormone‐dependent short‐term partner preferences appear to be critical for the formation of consort bonds and to facilitate mating between unfamiliar partners. Socially based partner preferences tend to dampen hormonal influences and may lead to long‐term familiarity. Long‐term familiarity decreases sexual interactions and may be a proximate mechanism underlying incest avoidance and periodic male troop transfers. Both males and females exhibit mate competition under certain conditions, and their dominance rank can modify sexual and aggressive behavior by either optimizing or reducing hormone‐dependent changes. These interaction effects between social and hormonal variables also have relevance for the design and interpretation of laboratory experiments. © 1996 Wiley‐Liss, Inc.

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Seasonal weight changes in male rhesus monkeys (Macaca mulatta)

Bernstein

Weed

Judge

et al. 1989

American J Primatol

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Adult male rhesus monkeys lose weight during the breeding season and regain it during the nonbreeding season. The annual pattern of maximum weight gain just prior to the onset of breeding resembles the seasonal "fattening" seen in squirrel monkeys, but the period of weight gain is less discrete. The magnitude of weight change is less in younger males, in that sexually immature males gain weight in both seasons, but significantly less during the breeding season. Females do not lose weight during the breeding season. Post hoc analyses revealed no significant correlations between male testosterone levels, dominance ranks, weights, or weight changes. The heaviest animals as juveniles were predictably the heaviest as adolescents. The timing of seasonal changes in testosterone did not correlate with the timing of changes in weight; weight losses followed the rise in testosterone, and weight gains continued until early in the breeding season after testosterone levels had already begun to rise. It is suggested that seasonal hormonal changes may influence activities in individuals and that changes in the activities of particular group members may alter the activity patterns of other group members. This alteration of activity patterns due to group influences on individuals as well as individual inf luences on the group may explain why hormonal regulation of seasonal weight appears to be indirect and why individuals (juveniles) experiencing no seasonal hormonal changes nonetheless show differences in activity patterns and seasonal weight changes.

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Role Behavior of an Agonadal Alpha-Male Rhesus Monkey in a Heterosexual Group

Cited by 11 publications

References 5 publications

Gonadectomy negatively impacts social behavior of adolescent male primates

Gonadectomy negatively impacts social behavior of adolescent male primates

Social factors modulate the effects of hormones on the sexual and aggressive behavior of macaques

Seasonal weight changes in male rhesus monkeys (Macaca mulatta)

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