Why do bonobo’s have stress?

In nature, bonobos live together in large communities, but smaller groups regularly isolate themselves to look for food, for example. During the period that the bonobos are separated from other group members, a lot can happen, from new friendships to quarrels, which has made the mutual relationship uncertain. When a bonobo sees a group member again after some time, it is unclear to them whether this reunion will be a positive or a negative experience. The bonobos in Planckendael are housed like wild bonobos: in smaller groups whose composition sometimes changes. This allowed us to study in detail how the bonobos react to such a reunion.

The reunion of group members is definitely not a calm event

From our behaviour observations, we can conclude that a reunion between bonobos is accompanied by a lot of energy and noise, a slight increase in aggressive behaviour, but also increased stress levels. How do we know the latter? Because we had already trained Planckendael's bonobos to use touchscreens in previous research, we were able to use this method to reliably measure the emotions of the bonobos during the reunion with their group mates, whom they had sometimes not seen for a few days. We let the bonobos solve a simple touchscreen task on days before, during and after such a group reunion and analysed how the bonobos solved this task.

As expected, we did find that a reunion for bonobos is accompanied by a slight level of stress. We also discovered that this stress was only short-lived: the day after the reunion the stress had already disappeared. And they had a trick up their sleeves to accomplish that.

The solution according to the bonobos?

Sex! We observed that when the bonobos saw their group mates again that, in addition to a slight increase in aggressive behaviour, they also had much more sexual contact.

Not surprising, because bonobos are known to resolve tensions in the group with sex. So, what's new about this research? Well, we found a direct link between having sex and reduced stress levels. Whether this means that the bonobos have more sex because they had less stress, or that having sex makes them feel good, is not yet fully understood. What is clear though, is that bonobos, entirely in their own way, are masters in dealing with stress.

Want to know more? You can read the scientific paper here.