why are we decussated (crossed over) was Re: Gender and Cognitive Style

Timothy Bates (tbates@bunyip.bhs.mq.edu.au)
Sun, 22 Nov 1998 19:24:55 +1100

joe said:
>It has also been hypothecized that opposed control has survival
>value; If one is attacked from one side, it is better for the
>sensorimotor complex for that side to be on the other (leeward) side
>so that a head blow would not disable it and it would remain available
>for defence.

deperation. how many attacked ancestors survived when one hemisphere was disabled by nimbly using the other ;-)

One idea that sounds reasonable to me is that by crossing the input and output, an organism with paired inputs (ears, lateral line sensors) will steer towards the signal (moving away increases the ouput of the near sensor and so steers back on track).

One idea that i had is that all this follows from the fact that the eyes _don't_ cross over they just course directly back: left of left eye to left hemisphere etc. That has the unfortunate effect of representing the right visual field in the left hemisphere: all else follows from this.


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