If dolphins had hands instead of flippers, they might have given us a run for our money. Dolphins are extraordinarily smart and hypersocial, quite akin to humans. They can solve complex problems, use tools, know and remember other dolphins by name ever after decades (they have a particular whistle unique to each individual), and have their own language composed of various combinations of clicks, whistles, and loud pulses, as well as nonverbal gestures.
Since 1992, studies of bottlenose dolphins in Shark Bay, Western Australia, have also shown that these crafty marine mammals also form alliances, with males banding together to pursue a common goal. In this instance, the objective is securing more mating opportunities, by guarding females and keeping them from competing groups. It can be rough, it can be gruesome, but it’s also a testament to the dolphin’s remarkably complex social behavior. But that was barely scratching the surface.
A new study out today in the journal PNAS shows that the dolphins actually form multi-order alliance networks that are far more intricate than previously believed at first glance.
Dolphins together strong
Researchers at the University of Bristol, University of Zurich, University of New South Wales, and the University of Massachusetts analyzed the social structure of a group of 121 adult male Indo-Pacific bottlenose dolphins at Shark Bay and constructed a model of their alliances.
This study confirmed some previous findings, including that males form pairs and trios to sequester and control the movement of females in estrus for periods ranging from less than an hour to weeks. Then there are second-order alliances of four to 14 unrelated males that compete with other allied groups over access to females. These second-order alliances are formed out of two or more 1st order alliances and their bond can last for decades (the average lifespan of a dolphin is 40 years).
But that’s not all. There are also third-order alliances that occur between cooperating second-order alliances. The existence of third-order alliances is not new knowledge, but the new study found that this type of inter-group cooperation is more important than previously thought, significantly contributing to male reproductive success.
“The second order alliances are really the equivalent of groups in other species such as primates. These 3rd order alliances are intergroup alliances,” co-lead author Richard Connor, Professor Emeritus at the University of Massachusetts and now affiliated with Florida International University, told ZME Science.
The purpose of these alliances is to capture and sequester females for mating. The stronger these alliances, the more effective the males are at stealing females and defending their mating rights against other groups. In the new study, the researchers showed that third-order alliances allow males to keep their females longer.
“If you are a trio alone with your female, third-order allies may be an important backup,” said Connor.
The researchers add that these alliances are so obvious to the trained eye that they’ve given them names. These include cheeky groups like the Wow Crowd, the Krocker Spaniels, and the Prima Donnas. But it wasn’t exactly easy to see them in action. It took many years of regular surveys, in which the researchers approached dolphins on boats, took pictures of individuals, and did regular follow-ups of male alliances and female consorts.
“The weather is always our biggest challenge; we can only go out on the bay in search of dolphins about half the days that we are in the field. The rest are too choppy because of high winds to find dolphins and see what they are doing in detail,” said Connor.
“The first big 3rd-order alliance fight we saw — meaning that a number of 2nd-order alliances were involved, some actually helping each other rather than simply competing — was amazing!”
Second-order alliances are basically the equivalent of groups in other social species, such as primates. But unlike chimpanzees, groups of dolphins don’t actually defend females or territory. “They live in an open society with continually overlapping male and female ranges. Thus, 3rd-order alliances are intergroup alliances,” Connor said.
“Having shown the importance of intergroup alliances for male success, we compare the dolphin system to chimpanzees and humans. The dolphins’ fission-fusion grouping, life history, and promiscuous mating system are very chimpanzee-like, but they form intergroup alliances like humans. The leading model for the evolution of human intergroup alliances links them to male-female pair bonds and male parental investment. While that model may well be correct for humans, we show that pair bonds and male parental investment are not necessary for the evolution of intergroup alliances,” he added.
These multi-order alliances, however, are very human-like. Imagine a group of humans that cooperate with a nearby village to secure their land against other villages, which can grow into tribes, confederations, kingdoms, republics, unions, or federations. These intricate webs of cooperation and collaboration are partly what made out species so successful, enabling trade, the dissemination of culture, and prosperity. Similarly, dolphins derive tangible benefits from harboring alliances with strangers whose goals align with theirs, securing mating rights for longer and thus enhancing their ability to pass on their genes.
While other mammals like lions or chimps form relatively simple second-order alliances, only humans surpass dolphins’ alliance networks in terms of size and complexity.
“Strategic, multi-level alliance formation was once thought unique to humans, say a local football team, provincial team and then national team, or local council, state government and even international alliances – this level of cooperation is a hallmark of our intelligence and success as a species. Here we see a remarkable three levels of alliance formation in a population of a species other than our own,” co-author Simon Allen, Senior Lecturer at Bristol’s School of Biological Sciences, told ZME Science.
Allen adds that it’s no accident that the researchers have been studying dolphin alliances at Shark Bay for more than four decades. Located on the Indian Ocean coast at the most westerly point of Australia, Shark Bay is home to vast sea-grass beds covering more than 4,800 square kilometers. These lush seagrass beds are a haven for marine species, including dugongs, dolphins, sharks, rays, turtles, and fish, as well as the endangered green and loggerhead turtles.
But this paradise is a grave peril, owed to human-made climate change.
“We are very concerned about the impact of climate change and over-fishing in Shark Bay, a Marine Protected Area and UNESCO-listed World Heritage site. This ecosystem and these remarkable dolphins have been negatively impacted by marine heatwaves and then the massive influx of recreational fishers during the global pandemic. The place needs genuine protection, not just protection on paper. Resilient ecosystems need nurseries, like seagrass meadows, just as they need apex predators, like big fish, sharks, and dolphins. We need to be mindful of what we take and what is coming in future years, or we might just be tracking the demise of one of the biggest-brained, most socially complex populations of wildlife with whom we are fortunate enough to share the planet,” Allen said.