Dolphins are intelligent and extremely social animals, who, like humans, seem to have both close bonds with family and friends, and an extended social network of friends and acquaintances. After listening to 132 hours of audio recordings captured of a group of wild dolphins in Australia, marine biologist Emma Chereskin found that the dolphins would keep in touch with their acquaintances by whistling their distinctive signature whistles in their direction. The research was published in the journal Current Biology.