A new study has found that dolphins form the animal world's closest alliances. File Photo by Neirfy/Shutterstock
Aug. 30 (UPI) -- A new study has revealed that dolphins are able to build complex alliances that form the largest cooperative societies on Earth, outside of humans.
Behavioral ecologist Richard Connor and a team of researchers analyzed data collected between 2001 and 2006 on 121 male dolphins as a part of the study. They found a well-connected social network with every male being connected to another one, either directly or indirectly.
"It's an exciting finding that helps bridge the immense, perceived gap between humans and other animals," Mauricio Cantor, a behavioral ecologist at Oregon State University who was not involved in the study, told Science.org.
Each male had on average 22 allies and some had as many as 50.
According to the study, male dolphins bond with one another by swimming and diving, petting, holding flippers, engaging in sex and whistling. The ones who have the strongest social bonds spend the most time with female dolphins.
Richard Wrangham, a Harvard University primatologist, said that Connor's study supported the idea of the "social brain hypothesis," which says that the brain evolves based on the need to keep track of numerous social relationships.
"The dolphins provide a dramatic demonstration of the positive correlation between brain size and social complexity," Wrangham told Science.org.
Dolphins are similar to chimpanzees because males and females don't form long lasting pairs.
"Our results show that intergroup alliances can emerge without these behaviors, and from a social and mating system that is more chimpanzee-like," Connor said.