Grooming is a common behavior observed in primates. For some primates, grooming might be performed according to one’s social ranking, with middle-ranking individuals grooming more often than both high and low-ranking individuals (Xia, et al., 2021). In this hypothesis, individuals use grooming to establish rank within the social hierarchy. The steeper the social hierarchy is, the more time these middle-ranking individuals will spend grooming in an attempt to maintain their social ranking–by grooming the lower-ranking–or in an attempt to climb the hierarchy–by grooming higher- ranking (Xia, et al., 2021).

A second hypothesis explaining allogrooming regards grooming as a hygienic behavior with primates primarily grooming in locations on the body where the individual being groomed cannot reach themselves (Pfoh, et al., 2021). In long-tailed macaques, one study shows that female-to-female grooming interactions tended to be on the head or front, while male-to-male grooming interactions tended to be on the back or tail (Sonlanki, et al., 2020). In our study, we define the head and back as being hard to reach locations, while the tail, arms, legs and front are easy to reach locations. Using our definitions, this means that Sonlanki, et al. (2020) suggests both males and female perform allogrooming for hygiene (hard to reach locations) and for another reason (easy to reach locations). Our study was conducted on long-tailed macaques (Macaca fascicularis), using sex and size as a proxy for dominance. Since troops typically consider the largest male the most dominant individual (Hakim et al., 2023), larger individuals were considered “more dominant” than smaller individuals and males were considered the dominant sex. We predict intermediate-sized females will exhibit the most grooming behavior followed by medium-sized males. We also predict that intermediate-sized individuals will primarily groom individuals that are significantly larger or significantly smaller than themselves (Xia, et al., 2021), primarily focusing on areas that individuals find difficult to groom independently (Pfoh, et al., 2021).

Additionally, while grooming, primates use their hands and mouth to move fur and pick skin, insects, and other parasites off of the individual being groomed. Other studies of primate handedness have found a tendency toward left-handed priority (Zhao, et al., 2012). In our study we also examined this tendency in Macaques.

This study aims to enhance our understanding of social grooming among macaques and primates overall. This specific behavior is crucial for understanding macaques more deeply, as it can reveal insights into their relationships, hierarchy, and communication patterns.

Submitted as part of the Behavioral Ecology Lab (BIO-327L-MM01) course.

Creator

• McDade, Andrew

• Ready, Hailey

Contributors

• Indianapolis Zoo

Language

• English

Keyword

• grooming

• primates

• social ranking

• social hierarchy

• allogrooming

• long-tailed macaques

Date created

• 2024

Resource type

• Poster

Rights statement

• http://rightsstatements.org/vocab/InC/1.0/