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Friday Fun: Dolphin Stampede

The views expressed are those of the author and are not necessarily those of Scientific American.


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This video (via the Washington Post, CBS Evening News, and Dana Point Whale Watch) showing a super-pod of perhaps 2000 dolphins off the coast of southern California, made the rounds last week.

Dolphin society is typically described in the same way as primate society. Fission-fusion societies among dolphins are characterized by two levels of social hierarchy: groups of two or three related males (“first-order alliances”) work together to guard one or more females from other males. Those first-order alliances combine to form larger groups (“second-order alliances”) which cooperate to “steal” females from other groups first- and second-order alliances. Since the individuals in first- and second-order alliances are related and therefore share genes, this sort of cooperation can be explained by kin selection.

Research that was published in 2010 described a new kind of dolphin group formation: a set of alliances among second-order alliances, or “second-order super-alliances.” These third-order alliances are comprised of individuals who are not related, so these super-alliances can not be explained by kin selection. It also can’t be described by reciprocal altruism, because previous interactions did not sufficiently predict future interactions (in other words, they are not organized on a tit-for-tat system). It turns out that second-order super-alliances are incredibly familiar to human friend groups: each dolphin ranks the relative importance of his friendships with other dolphins, but that is balanced by his prediction of how his dolphin friends rank him as well! It is that sort of mental calculus that helps a dolphin decide who to help and when to help them.

Second-order super-alliances are made of, on average, around twenty-five males. But a pod of over 2000 individuals? I’m not sure what explains that, but it seems to be rare.

Related:
What Can Dolphins Tell Us About The Evolution of Friendship?

Jason G. Goldman About the Author: Dr. Jason G. Goldman received his Ph.D. in Developmental Psychology at the University of Southern California, where he studied the evolutionary and developmental origins of the mind in humans and non-human animals. Jason is also an editor at ScienceSeeker and Editor of Open Lab 2010. He lives in Los Angeles, CA. Follow on . Follow on Twitter @jgold85.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. mgoldstein 1:01 pm 03/2/2012

    No idea what causes these huge pods, but I’ve seen hundreds to thousands of dolphins all the way to the horizon a couple times off southern California. Perhaps it has to do with food aggregation? Sardines and anchovies also form large groups.

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  2. 2. kdearborn 11:06 pm 03/5/2012

    This video shows long-beaked common dolphins that frequently feed off the California coast in pods of 100s to 1000s of individuals. While bottlenose dolphins are the species that most people think of when they refer to dolphins, there are at least 36 different species of dolphin and several smaller species congregate in large pods when food is available. The animals in the video are displaying the typical behavior of common dolphins to travel in a large group toward food. While 2000 common dolphins is an impressive sight it is not unusual in Southern California.

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