The fact that we share around 98% of our DNA with chimpanzees allows us to ensure that it is our closest living relative in the animal kingdom. So it is not surprising that they display behaviors close to ours, such as feeling stressed .
A recent study, carried out by the Max Planck Institute for Evolutionary Anthropology, based in Leipzig (Germany), has investigated these primates, which have a social structure led by males – who establish a hierarchy of dominance among them -.
As these scientists point out in a press release, managing to maintain a high social status, of authority over others, often implies a very high energy drain. So the team examined the potential sources of energetic and psychosocial stress that chimpanzees are exposed to on a daily basis , “and especially during periods when males compete intensely for dominance and for mating opportunities,” says Anna Preis, one of the authors of the study.
In this way, they found that the levels of cortisol in the urine – this hormone is released in response to stress – were higher in males during unstable periods – in which the hierarchy was not well defined – compared to those others were more stable – in which they knew what to expect at all times in their relationship with the other males – while the rates of aggression among them showed an inverse pattern: they were higher in the more stable stages.
Unpredictability is particularly stressful
Thus, these findings suggest that uncertainty in dominance relationships within the group exposes males to psychosocial stress, despite lower rates of aggressive interactions during these stages. This is consistent with other studies showing that unpredictability in social relationships is particularly stressful in primates, including humans, the researchers note.
“Our study shows that open aggression was not the source of the high stress levels of the males during the periods of greatest competition with each other, but that they were more affected by the social uncertainty induced by these competitive periods,” says Preis.
Another of the study authors, Roman Wittig, explains that one of the main findings of this research “is that male chimpanzees adjust competitive behaviors to context-dependent conditions. When the risk of escalation of conflict was high, males they avoided aggressive behaviors to reduce the risk of injury . “
As Wittig recalls, chimpanzees are very territorial animals and they do not hesitate to defend their territories, all together, against intruders, so that “males could avoid aggressive behaviors when the dominance relationship in their group is unstable , it is not clear, as part of a conflict management strategy that allows them to cooperate as a group during those periods. “
Image: Anna Preis
