Male bonding reduces stress in monkeys

Male macaques who have strong friendships cope with stress much better than loners.
15 December 2014

Interview with 

Chris Young, University of Göttingen


We all sometimes need a friend to help us through hard times and that's true not just of humans. A new study by at team from Göttingen and Lincoln Universities has shown that, among our monkey cousins too, those with more friends are less stressed when times are tough, as University of Göttingen scientist Chris Young Macaques huggingexplained to Khalil Thirlaway...

Chris Y -   Barbary macaques are one of a few primate species where we see strong affiliation between the males.  So, the males perform lesser friendly interactions with each other, they groom each other, socialise together.  We wanted to try and examine exactly what benefits males are gaining from cooperating together.  We know that long term stress is bad for their well-being and their health.  So, if individuals can reduce their stress levels and this can help them greatly in their day to day lives as they'll have a better overall immune function, a better overall health, and a better overall well-being.

Khalil -   How are you measuring the stress and the effect of the bonding?

Chris Y -   We look at glucocorticoids which is a hormone which is excreted or produced during stressful times so the higher your levels of glucocorticoids, the higher your stress levels.  So, we collected faecal samples which means that we don't have to capture the animals or anything like this.  It's a natural method and non-invasive.  We measure their social bonds through the rates at which they affiliate with each other.  So, how often they sit together or groom together, feed together, things like these and then you have a proportion of individuals that socialise much less and once that socialise much more.  We were interested in, if those that have these strong social bonds that socialise the most gain stress reducing benefits.

Khalil -   What were the stress reducing benefits that you were noticing in these macaques?

Chris Y -   Males lead to quite a hectic life.  Every day, there are lots of events which are very stressful so you can receive aggression from other individuals in the group, you can not get access to the best food sources, access to mating, and Morocco is a very cold place in the winter and the summer can be 40 degrees and bright sunshine and no shades and then in the winter, you can have sleet storms and snow and rain.  So, these are the two factors we really wanted to examine.

Khalil -   Has research been done in humans about this buffering effect?  How closely related evolutionarily are macaques to humans?

Chris Y -   Well, we split off quite a number of millions of years ago on the evolutionary ladder, but I think what the study shows is that what we see in modern day human society where individuals who are very lonely tend to get a lot sicker and they have a shorter lifetime and often suffer from depression and things.  These things are all linked to having poor social relationships.  Several studies have pointed to the fact that this might be alluded to modern society where individuals are no longer in touch with their roots, and with things like modern technology you no longer have to socialise and interact with other individuals.  I think what the study is showing is that this need even in males for social contact can actually come from much further back down the line and having social contact with other individuals might have many benefits which the virtual world might not be able to provide.

Khalil -   I guess in humans, there are easier ways to measure stress than going through faecal samples.

Chris Y -   Yeah, human psychology is a bit easier to measure stress.  They can conduct questionnaires and interviews with subjects, and obviously, unlike primates, they can respond and answer the questions.  But there has been some research in humans and they find that individuals who perceive themselves as being lonely or have fewer friends tend to cope less well in stressful situations and they also live a shorter life and are more susceptible to diseases.  Similar to what we find in our study then, individuals with lower quality social relationships tend to do less well.

Khalil -   So, close friendships really are very important in both your emotional health and your physical health.

Chris Y -   Yeah, exactly.  I think it's very nice to know that in times of need keeping a few very good close companions, like we see in Barbary macaques, is a very important thing.


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