August 1, 2012
Wild Bottlenose Dolphins: Research Shows They Can Be Stuck Up
Lee Rannals for redOrbit.com — Your Universe Online
Talk about stuck up, new research shows that bottlenose dolphins form elite societies and cliques.
Scientists found that wild bottlenose dolphins bond over the use of tools, with distinct cliques and classes forming over decades as a result of their skills. The research suggests that humans are not the only animal species that understand what its like to be picked last in gym class.
According to the findings, the dolphins in the communities share their knowledge only with those in their own circle, passing it down the family line.
Georgetown University noticed that some dolphins in Shark Bay, Australia used a sponge to protect their beaks while hunting, and others did not. The team wanted to understand why the practice had not spread.
They found the tool was first used by a single dolphin nicknamed "Sponging Eve," after she scraped her nose while foraging for food in rough sand. The dolphin broke off a piece of sea sponge to protect her, and taught the behavior to her offspring.
Two decades later, the knowledge of using a sponge to protect noses spread among the whole dolphin population in the area.
Scientists found 36 spongers and 69 non-spongers in the area over a 22 year period.
“Spongers were more cliquish, had more sponger associates and stronger bonds with each other than with non-spongers," the researchers wrote in the journal Nature
Communications. “Like humans who preferentially associate with others who share their subculture, tool-using dolphins prefer others like themselves, strongly suggesting that sponge tool-use is a cultural behavior,” they continued.
Scientists suggest that the dolphins may have a tendency to associate with those most like themselves.
“We sometimes think that traits such as culture are exclusively human, but a growing body of literature proves otherwise," Janet Mann, the team leader, wrote in the journal.
The researchers believe that the cliques are formed for social reasons, rather than for practical reasons.
“As sponging is a solitary behavior, affiliation between spongers would not be based on collective foraging, but rather on identifying other individuals as spongers," they wrote in the journal. “We suggest that spongers also share in-group identity, but affiliation is a consequence of similarity in the socially learned trait, a scenario that resonates with human culture."
The researchers said that spongers were more cliquish, had more sponger associates and stronger bonds with each other than those dolphins that were non-spongers.
The study also found that the behavior was stronger in females, which were better at maintaining alliances.
The dolphin sub-cultures are believed to be the result of socially-learned behavior rather than innate traits.