How Primates Deal With Stress: Behavior, Body, and Genes

Jenn Hoskins
17th February, 2024

How Primates Deal With Stress: Behavior, Body, and Genes

A thermal camera captures the physiological signature of stress, revealing a macaque's emotional arousal in response to a predator through changes in its nose temperature.

Image adapted from: Bhattacharjee et al. / CC BY (Source)
Animals routinely face challenging situations, and their ability to manage these – a process called coping – is crucial for survival and reproductive success. However, not all animals cope in the same way, and understanding why this variation exists is a key question in behavioral biology. Researchers at Utrecht University recently investigated the factors influencing coping strategies in long-tailed macaques[1]. The study focused on identifying how behavior, emotional state, personality, and genetics combine to shape how these monkeys respond to stressful events. Coping can manifest in different ways; some animals might avoid conflict, while others might confront it directly. The researchers categorized coping styles into “nonaggression-based” and “aggression-based” approaches. To assess coping styles, the researchers observed the macaques’ behavior in various situations. They also measured emotional arousal using infrared thermography – a technique that detects temperature changes in the face. The idea is that changes in facial temperature can indicate levels of emotional activation. Furthermore, the team assessed the monkeys’ personalities, identifying consistent individual differences in temperament and behavior. Finally, they examined a specific gene, catechol-O-methyltransferase (COMT), which plays a role in regulating stress responses in humans and other primates. This gene has a common variation, where individuals can have either a valine (Val) or methionine (Met) version. The findings revealed a link between personality, the COMT gene variation, and coping style. Monkeys with a particular version of the COMT gene were more likely to exhibit aggression-based coping. Interestingly, these monkeys also tended to have lower average facial temperatures, suggesting they experienced less emotional arousal during stressful situations. This aligns with earlier work suggesting that the magnitude of physiological responses doesn’t simply equate to ‘stress’ but reflects the demands of the situation[2]. The researchers propose that lower emotional arousal in aggression-based copers might allow for quicker, more decisive action in confrontational scenarios. This study builds on previous research demonstrating that individual differences in stress responses can have significant consequences for fitness[3]. That earlier work showed that a strong adrenocortical response to stress could actually reduce survival in birds, suggesting that a ‘lower stress’ response isn’t always detrimental. The current study adds nuance by showing that coping style – and the underlying mechanisms driving it – are key. The observed connection between personality and coping also resonates with studies on baboons, where distinct personality traits like “Nice,” “Aloof,” and “Loner” were linked to different social behaviors and stress levels[4]. While the macaques weren’t categorized using those exact labels, the aggression-based and nonaggression-based coping styles represent similar dimensions of social interaction and response to conflict. The baboon study highlighted that personality can influence social bonds and glucocorticoid levels, and the macaque study expands on this by demonstrating a genetic component to coping styles. The Utrecht University team’s work demonstrates a complex interplay between various factors governing coping in primates. It suggests that coping isn’t simply a matter of being ‘stressed’ or ‘not stressed,’ but rather a multifaceted strategy shaped by personality, genetics, and emotional regulation. The identification of the COMT gene as a contributing factor opens avenues for further research into the biological basis of coping and its evolutionary implications.

GeneticsAnimal Science

References

Main Study

1) Behavioral, physiological, and genetic drivers of coping in a non-human primate.

Published 16th February, 2024

https://doi.org/10.1016/j.isci.2024.108890

Related Studies

2) Stress revisited: a critical evaluation of the stress concept.

https://doi.org/10.1016/j.neubiorev.2011.02.003

3) Stress response during development predicts fitness in a wild, long lived vertebrate.

Journal: Proceedings of the National Academy of Sciences of the United States of America, Issue: Vol 104, Issue 21, May 2007

4) Variation in personality and fitness in wild female baboons.

https://doi.org/10.1073/pnas.1210780109


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