Why are mammilian brains split in two laterally

[dr.syntax]

? As far as I know this is true for all vertebrates ? What is the evolutionary reasoning that explains this ? ...dr.syntax

[iNow]

Because through evolution that proved to be the more successful strategy. If one side gets hurt, the other side can assume control over most functions. The independence of sides gives great protection from the adverse effects of unilateral brain injury (read: most brain injury tends to be life threatening. having redundancy tends to be the safer bet. through time, each side has taken on slightly different function, but the idea is that we have a back-up if one side gets injured).

 

 

EDIT to add: Here's a great link discussing the question of hemispheres: http://faculty.washington.edu/chudler/split.html

Edited August 31, 2009 by iNow