Extrait de l'article:
Bonobos shriek when attacked. But they produce different sounds depending on whether this happens with or without provocation. This distinction adds evidence to the idea that they sense when others have treated them unfairly.
A bystander sometimes intervenes, supporting or consoling the attacked ape. This could mean that bonobos also take into account the fairness of how others are treated, something so far thought to be limited to humans.
It suggests that the basis of fairness is probably present in bonobos, says Zanna Clay of the University of Birmingham, UK. Her team analysed over 800 hours of videos of two groups of bonobos at the Lola Ya Bonobo sanctuary in the Democratic Republic of the Congo.
When one bonobo attacks another, there is sometimes an obvious reason, such as fighting over food. On other occasions it appears unprovoked, and in those cases the scream is longer, more high-pitched and harsher-sounding (...)
“Bonobos may be aware of what should and shouldn’t happen to them within their social norms“
“This suggests they’re aware of what should and shouldn’t happen to them,” says Clay. “It’s sort of like if someone comes up to you and slaps you in the face: your vocalisations are quite different to if you’re in a rough game and you’re expecting someone to slap you. So we think it taps into something that we do as humans.”
Shrieks in response to unprovoked attacks might be signals to the assailant to back off or cries for help. “We think these screams are actually eliciting interventions and help from third parties,” says Clay. “It probably also inhibits the aggressor from doing it again.”
Sarah Brosnan at Georgia State University, Atlanta, says this is the first study that demonstrates not only that individuals react to violations of social expectations, but do so in a way that may be a signal to others that a violation has occurred.