The myth of a simple relation between space and aggression in captive primates

Abstract

This paper reviews literature on the relation between captive environments and social behavior, particularly aggressive behavior, in monkeys and apes. The conclusion is that theories of "crowding" and "stress" are too simplistic to account for the observed relation. Instead, it is suggested that environmental effects be investigated from the standpoint of behavioral adjustment. Primates show behavior patterns that seem to aim at the avoidance of conflict and the reduction of social tensions. Such coping mechanisms are expected to be especially effective in groups that have lived in a particular environment for a long time. As an indication that this may be so, data on stable groups of rhesus monkeys under three very different conditions show a remarkable similarity in aggression rate.

Fine‐tuning of social play in juvenile lowland gorillas (gorilla gorilla gorilla)

“…In fact, in high-density conditions juveniles avoid to interact with the adults. Specifically, adult avoidance fits with the ''coping-model,'' which predicts that individuals stay away from risky partners, especially when escape opportunities are limited (de Waal, 1989b;Judge, 2000;Judge & de Waal, 1993;Cordoni & Palagi, in press). Among juvenile Yerkes chimpanzees, Aureli and de Waal (1997) found an increase of play behavior under highdensity conditions.…”

“…It is possible to distinguish two different situations: short-term crowding (from a few hours to a few days) and long-term crowding (many years or generation) (Aureli & de Waal, 1997;Caws & Aureli, 2003;de Waal, 1989b). …”

The Social Behavior of Brown Spider Monkeys (Ateles hybridus) in a Fragmented Forest in Colombia

“…However, we observed a high proportion of female-to-male grooming, which differs from previous studies in less disturbed habitats where this behavior was rather uncommon (Slater et al 2009). Under crowding and stress conditions, primate behavioral patterns serve to avoid conflict and reduce social tensions (de Waal 1989), and researchers have suggested that grooming acts as a mechanism to release stress in several primate species, in which both the groomed (Aureli et al 1999;Boccia et al 1989;Gust et al 1993) and the groomer (Aureli and Yates 2009;Shutt et al 2007) may benefit by reducing physiological tension levels among individuals (Schino et al 1988), indicated by reductions in the heart rate (Aureli et al 1999), reduced levels of glucocorticoids (Shutt et al 2007;Wittig et al 2008), or increased endorphin release (Keverne et al 1989). Spider monkeys in fragmented habitats and in captivity have higher fecal cortisol levels, which may be the result of metabolic and behavioral stress (RangelNegrin et al 2009).…”

“…In small forest fragments, social crowding can increase the rates of aggressive interactions, which could lead to increased physiological and social stress (Honess and Marin 2006). Nonetheless, researchers have suggested that under stressful conditions such as those of fragmentation (Rangel-Negrin et al 2009), primates display behavior patterns that help to reduce conflict and social tension (de Waal 1989), and affiliative behaviors such as grooming may increase (Honess and Marin 2006), acting as a stress-release mechanism (Dunbar 2010;Goosen 1981;Schino et al 1988) to alleviate the intense competition for space and resources.…”

The Effect of Crowding on the Social Behavior of the Cooperatively Breeding Cotton-Top Tamarins (Saguinus oedipus)

“…De Waal proposed that specific behavioral mechanisms would be expected in social species such as primates to manage the risk of conflict under conditions that increase aggression-facilitating situations: the coping model (de Waal 1989). This model is supported by studies of various primate species showing that primates use preconflict strategies to avoid conflicts and reduce tension (Judge 2000;Koyama and Palagi 2006).…”