A group of four males allied to share a female (Source: Simon Allen)
The researchers, led by Richard Connor of Dartmouth University and Stephanie King of the University of Bristol, studied alliances within a group of 121 male dolphins (Tursiops truncatus) living in Shark Bay, Western Australia. These samples form first-level cooperative networks, consisting of two to three males, to share access to a female. These primary cores then form an alliance in the larger second level groups (consisting of 4 to 14 samples) and finally the third level.
Intergroup cooperation in humans was thought to be unique and based on two other characteristics that distinguished us from our common ancestor with chimpanzees: the development of marital bonds and parental care by males. “However, our results show that alliances between groups can emerge even without these characteristics,” comments Connor, “of a social and mating system more similar to that of chimpanzees.”
“Infuriatingly humble social media buff. Twitter advocate. Writer. Internet nerd.”