Anxiety in Geoffroy's spider monkeys (Ateles geoffroyi): Can scratching be used as an indicator?

Abstract

Self-directed behavior, such as self-scratching (hereafter, scratching), occurs in several taxa across the animal kingdom, including nonhuman primates. There is substantial evidence that scratching is an indicator of anxiety-like emotions in a variety of nonhuman primate species. Despite its importance as a window into emotional states, few studies have investigated scratching in Platyrrhines. We investigated scratching patterns of 24 Geoffroy's spider monkeys (Ateles geoffroyi) belonging to a group living in the Otoch Ma'ax Yetel Kooh protected area in the Yucatàn peninsula (Mexico). We assessed whether scratching could be used as an indicator of anxiety levels in this species by testing predictions based on contexts and behaviors associated with risk and uncertainty. We found no effect of the subject's sex and age, subgroup size, male presence, and the occurrence of fusions between subgroups on scratching rates. Similarly, we found no effect of infant proximity on their mother's scratching rates. Supporting our prediction, we found evidence that isolation from conspecifics affected scratching rates as individuals scratched more frequently the more time they spent isolated. Being in proximity with a partner with a relationship characterized by uncertainty affected scratching rates as individuals scratched more frequently when in proximity with a partner with whom they engaged in embraces (an indicator of uncertainty) than when in proximity with a partner with whom they did not exchange embraces. Our study provides insight into the factors affecting scratching in Geoffroy's spider monkeys, suggesting that scratching may indicate anxiety in this species at least in some contexts and thus opening a window into the emotional experience of another Platyrrhine monkey species.

Rapid facial mimicry in Platyrrhini: Play face replication in spider monkeys (Ateles fusciceps, Ateles hybridus, and Ateles paniscus)

“…Spider monkeys are known for their fission-fusion dynamics, where individuals within a group frequently split and rejoin in groups of varying composition. This necessitates the development of a complex communication system (Dell'Anna et al, 2022;Pellis & Pellis, 1997, 2011. Interindividual relationships among group members can be relatively unstable and change opportunistically.…”

Grooming reciprocation in Himalayan tahr and the cognitive constraint hypothesis

“…In Himalayan tahr, as in most primate and nonprimate group living species, emotionally based partner choice is likely to be the prevalent mechanism that underlies reciprocal exchanges of cooperative behaviors (see Dell'Anna et al, in preparation and Schweinfurth & Taborsky, 2020, for two exceptions). This hypothetical proximate mechanism only requires animals to be able to form differentiated social relationships (something that tahr have been shown to do; Schino et al, 2022), and does not require any form of “future thinking” or complex calculations (Schino & Aureli, 2009, 2017).…”

A preliminary attempt to investigate mirror self-recognition in Octopus vulgaris

“…Considering that the cleaning manoeuvre could also function as a displacement activity in common octopus ( Packard, 1963 ), the possibility cannot be excluded that some instances of this behaviour were in fact expressed in response to the stimuli used in the study, particularly if these were perceived as a source of distress. A relevant parallel here may be provided by self-scratching in primates, a displacement activity which is recognized as an indicator of anxiety ( Dell’Anna et al, 2022 ; Troisi, 2002 ) and which has been observed in response to reflected images of self ( Anderson and Gallup, 2015 ). Ultimately, investigating baseline rates for cleaning manoeuvres in the common octopus could provide insights regarding the interpretation of this behaviour in the presence of a mirror.…”