A New Hypothesis

Though this is more in an evolutionary vein than physiology, I thought it makes for an interesting topic for discussion.  Because while much of our current work on discovering what makes the brain "tick," animal models are the most common mode at getting about this information.  In other words, we often use animals such as rats and monkeys to serve as subjects and infer that the information we glean from them will apply relatively well for human systems.

Primates are often a great source of information in regards
to matching our physiological and social behaviors.

But not all species are alike.  Though these model systems often serve us well, some things can't be discovered through such a method- particularly higher order functioning.  But how are we different you might wonder.  Well the space assigned to various sorts of processing is one of the key elements.  Most other animals use the majority of their processing for dealing with sensory input like vision.  We differ in how we integrate the same type information as well as the additional work we do.  In fact there's a fascinating trend recently proposed by an anthropologist by the name of Dunbar.

He examined the density and amount of neocortical tissue found in apes and monkeys which led to an unusual correlation.  The best predictor for cortex size is the mean size of social groups that species interacts with.  So when species a of monkey lives within a social group of 20 individuals and species b interacts with 50, species b will have a larger degree of neocortex.

Dunbar used ration of brain tissue to body size to help
equate differences caused by simple body mass.

This correlation makes the basis for several interesting possible relations.  First, this might mean that there must be an evolutionary advantage to large social groups because species which work within such framework tend to have higher cognitive processes.

Second, it could be construed that being in a big group allows you to better use and hone your cognitive skills so you can process more with more developed cortex.

But last, and perhaps most interesting of all, the proposition that navigating large social groups is a highly complex process and requires a more developed cortex to handle.  This last one is of particular interest to me because it seems to tie psychology, sociology, and neuroscience into a single view.  The structure of our brain relates to our skill sets which assist in navigating the social world.  What a neat little bundle.

Of course there's still plenty of research to be done.   Just seeing a correlation does not immediately imply a causation.  And so far only primates have been examined.  How does this theory apply to animals like meercats or elephants who also live in large social groups?  What's your opinion?  Are we just seeing patterns that don't exist or is there really something to be said for this relation?