I think this would be the place to ask such a question, so here it is.
What are the current theories as to why the nervous system is mostly crossed?
What are the benefits which are thought to be gained from such a setup?
A novice wants to know. :-)
scott at psych.toronto.edu | "They are in you and in me; they created us,
Brian Scott | body & mind; and their preservation is the
Department of Psychology | ultimate rationale for our existence."
University of Toronto, Canada | - Richard Dawkins (The Selfish Gene)