Why does the left hemisphere control the right and the right hemisphere control the left? I googled it but didn't find a good answer regarding this. Could someone explain? Does this adaptation help in the speed of transmission of nerve impulses?
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Just to get the ball rolling here. This particular aspect of brain evolution is very old. The cross wiring of the hemispheres of the brain seems to be as old as the right and left hemispheres itself. It predates lizards - i.e. hundreds of millions of years ago. Digging back deeper, we can see that worms have bilateral brain structure, I would guess that this means that the phenomenon is as old as bilateral symmetry itself - putting the development in the pre-cambrian era, which is the best part of billion years ago. Echinoderms (like starfish) are 'missing links' in bilateral symmetry as their larval stage has bilateral symmetry even though the adult has radial symmetry. Such wiring may be so embedded in the way most animal body plans develop that it hasn't changed in evolutionary history. Still one might guess that the cross over of neurons in brain control is good for integrating the signals from both sides of the organism somehow. I'm sure someone else can post a better guess than this! |
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When I was in school it was discussed as an evolutionary survival advantage... If you are attacked from the right side, the left side of the brain is less likely to be damaged and can use the right sided limbs to fend off the attack as opposed to the right side being damaged and less responsive.. |
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