In Shark Bay, Western Australia, male bottlenose dolphins ( Tursiops aduncus ) form a complex hierarchy of social alliances. These alliances display a complexity like almost no other in the animal kingdom, almost comparable to that of humans .
Thus, at the first level, pairs or trios of unrelated males cooperate to raise individual females . Several first-order alliances cooperate in teams (second-order alliances) in the search for and defense of females, and several teams also work together (third-order alliances).
Complex social hierarchy
However, how dolphins classify these nested alliance relationships is unknown . So in a new study published in Nature , 30 years of behavioral data combined with 40 contemporary sound reproduction experiments for 14 male allies were used, recording responses with drone-mounted videos.
It was thus shown that males form a first-person social concept of cooperative team membership at the second-order alliance level, regardless of the history of the first-order alliance and the strength of the current relationship at the three levels of alliance. Such associative concepts develop through experience .
This behavior can help reduce tension between males in a situation that requires them to cooperate successfully. This synchronized and coordinated behavior between male allies can therefore promote cooperative behavior and regulate stress, as has been shown to occur in humans.
These results provide evidence that concepts based on cooperation are not unique to humans , and occur in other animal societies with extensive cooperation between non-relatives or nepotistic networks.
It is not the first evidence of the social complexity of these dolphins : unrelated bottlenose dolphins have been observed teaching themselves a new way to use a tool , a behavior that until now has only been discovered in humans and other great apes. In a practice called "shelling."
Shark Bay, a World Heritage area of Western Australia, is home to an iconic population of Indo-Pacific bottlenose dolphins. Only in this place have these cetaceans been observed using sea sponges, probably to protect their snouts as they search for prey in the sand on the ground .