Bottlenose Dolphins Form the Largest Multilevel Alliance Network Outside Humans

The researchers showed that male bottlenose dolphins form the largest multilevel alliance network known outside humans. These collaborative relationships between groups increase male dolphins’ access to controversial resources.

The scientists from the University of Zurich and the University of Massachusetts, analyzed association and consortium data to model the structure of alliances among 121 adult male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia. Their research can be found in the Proceedings of the National Academy of Sciences (PNAS).

Paper: ‘Strategic intergroup alliances increase access to a contested resource in male bottlenose dolphins’ Stephanie L. King, Richard C. Connor, Michael Krützen, Simon J. Allen and William B. Sherwin in The Proceedings of the National Academy of Sciences. https://www.pnas.org/doi/10.1073/pnas.2121723119

Male dolphins in Shark Bay form first-order alliances of two or three males to seek out consortiums with individual cooperative females. Secondary alliances between four and 14 unrelated males compete with other alliances for access to female dolphins, and third-order alliances are formed between cooperating secondary partnerships.

Co-author Dr Stephanie King, Associate Professor at the Bristol School of Biological Sciences, said: “Collaboration between allies is pervasive in human societies and is one of the hallmarks of our success. Our ability to form strategic and cooperative relationships at multiple social levels, such as national and international trade or military alliances, was once considered unique to our species. rather than alliance size, which allows males to spend more time with females and increases their reproductive success.”

Dr Simon Allen, a professor at the Bristol School of Biological Sciences who contributed to the research, said: “We show that the amount of time these teams of male dolphins spend hanging out with the females depends on how well the dolphins connect with their allies in the third category, namely social ties between alliances, these types leads to long-term benefits for

Intergroup cooperation in humans was thought to be unique and was due to two other traits that distinguish humans from our common ancestor with chimpanzees, the evolution of pair bonding and male parental care. “However, our results suggest that intergroup alliances lacking these characteristics may result from a social and mating system more similar to that of chimpanzees”; Professor emeritus at the University of Massachusetts and now affiliated with Florida International University, said Dr. Richard Connor, who led the work with King.

The publication of the importance of intergroup or third-tier alliances in dolphins in 2022 is of particular importance as the team celebrates the 40th anniversary of the start of dolphin research in Shark Bay in 1982 and the 30th anniversary of the publication of their discovery in 1992. on two levels. . Male Alliance Formation, also published in Proceedings of the National Academy of Sciences.

Study author and Director of the Institute of Anthropology at the University of Zurich, Professor Dr. Michael Krutzen added: “It is rare for an anthropology department to conduct research on animals other than primates, but our work shows that insights can be gained insights into the evolution of traits previously thought to be uniquely human by studying other higher primate taxa.” social and big-brained.

Dr King concluded: “Our study highlights that dolphin societies, as well as non-human primates, are valuable model systems for understanding human social and cognitive evolution.”