Dolphins form decade-long social bonds and cooperate between cliques to help each other find mates and fight off competitors, new research has found, behavior not previously confirmed among the animals.
“These dolphins have long-term stable alliances and they have intergroup alliances. Alliances of alliances of alliances, really,” he said. doctor richard connor, a behavioral ecologist at the University of Massachusetts Dartmouth and one of the paper’s lead authors. “But before our study, cooperative alliances between groups were thought to be unique to humans.”
the recommendations, published Monday in the journal Proceedings of the National Academy of Sciences, appear to support the “social brain” hypothesis: that mammalian brains evolved to be larger in size for animals keeping track of their interactions and networks. social. Humans and dolphins are the two animals with the largest brains relative to body size. “It’s not a coincidence,” Connor said.
Connor’s team of researchers collected data between 2001 and 2006 by conducting intensive boat surveys in Shark Bay, Western Australia. The researchers tracked the dolphins by watching and listening, using their unique identification whistles to tell them apart.
They observed 202 Indo-Pacific bottlenose dolphins (Tursiops aduncus), even during the peak mating season between September and November.
Back in the lab, they pored over data centered on 121 of these adult male dolphins to see patterns in their social networks. And for the next decade they continued to analyze animal alliances.
Dolphin social structures are fluid and complex. The researchers found alliances between two or three male dolphins, like best friends. The groups then expanded to 14 members. Together, they helped each other find females to herd and mate with, and helped steal females from other dolphins, as well as fend off any “stealing” attempts by rivals.
“What happens as a male, you might be in a trio, herding a female. And if someone comes to take that female, the other males on your team and your second-order alliance come in and help you,” she said. Dr. Stephanie King, professor of animal behavior at the University of Bristol and one of the study’s authors. “These guys have a very, very clear idea of who is on their team.”
These teams can last for decades and form when dolphins are still young, though they don’t tend to reap the rewards of parenthood until their mid-teens, King said. “It’s a significant investment that starts when they’re very young, and these relationships can last a lifetime.”
Sometimes, especially when groups of dolphins feel there is a risk to themselves, two second order alliances will also join together to form a larger team. As a result, among the dolphins observed by the scientists, each male was directly connected to between 22 and 50 dolphins.
The researchers’ observations show that in these groups, the closer the clique, and the stronger the bonds between dolphins, the more successful they are at attracting females.
It’s their cooperative relationships, rather than alliance size, that give males more reproductive success, King said.
Dolphins are already widely known to be highly social and cooperative, as well as being very good at adapting and teaching behaviors specific to their environment, he said. Stephanie Venn Watsonformer director of Translational Medicine and Research at the National Marine Mammal Foundation in San Diego, California, who was not involved in the study.
“One wouldn’t rule out the possibility that other cetaceans could develop similar alliances,” Venn-Watson said. “These complex behaviors are likely to be limited to large-brained mammals.”
According to the researchers behind the article, this is the only non-human example of this type of multilevel strategic alliance that has been observed. But these findings also highlight the cognitive demands these animals face, suggesting that dolphins’ large brains help them keep track of different relationships, Connor said.
“I would say that dolphins and humans have converged in the evolution of intergroup alliances, an incredibly complex social system,” Connor said. “And it’s amazing because we’re so different from dolphins.”