ainawgsd:

For the study, Cantor and colleagues cruised around the coastal lagoons of southern Brazil, taking photos of the dolphins they encountered to identify individuals. 
They amassed hundreds of records detailing which dolphins were fraternizing, and what they were doing together. They also used a harmless technique to collect genetic samples, which determined how and if the animals were related.
The results, published April 9 in the journal Biology Letters, revealed that the helper dolphins actively choose to spend time with one another. Whether individuals are related or members of the same age group or sex is less important; the strongest social ties form among dolphins with the same fishing technique.
“They prefer to be with each other, and not just when they’re cooperating with fishermen,” says Cantor, who is a National Geographic Explorer.

Janet Mann, a dolphin expert at Georgetown University in Washington, D.C., who was not involved with the new research, believes it reveals a cultural phenomenon.Though the definition of culture is debated, Mann says “anthropologists and psychologists agree on two basic criteria: that the behavior is socially learned, and that the behavior differentiates between groups.”