I know that the nerves cross and everything, but WHY did it happen that way evolutionarily? Is there a reason?
2007-01-29 01:48:03 · 8 answers · asked by Xenophonix 3 in Science & Mathematics ➔ Biology
It's still a mystery. Quote from Harvard neurologist:
"Incidentally, no one knows why the right half of the world tends to project to the left half of the cerebral hemispheres. The rule has important exceptions: the hemispheres of our cerebellum (a part of the brain concerned largely with movement control) get input largely from the same, not the opposite, half of the world. That complicates things for the brain, since the fibers connecting the cerebellum on one side to the motor part of the cerebral cortex on the other all have to cross from one side to the other. All that can be said with assurance is that this pattern is mysterious."
2007-01-29 02:07:13 · answer #1 · answered by . 4 · 1⤊ 1⤋
It should not be such a great mystery. The lens of the eye inverts images on the retina and also inverts left to right. Therefore the brain can learn to perceive "distorted" signals from the environment and properly interpret them. The left half of the vertical field of vision for both eyes is perceived only on the right side of the brain (etc.) yet there is no noticeable dividing line that we are aware of. Likely there was survival advantage to humans (and/or predecessors) to duplication of brain function (left and right) including inversion of hearing and sight and motor control. It has been said that having a dominant right hand helps manage the left to right inversion of sight. Of course lefties use a dominant left hand for the same purpose. The left and right brains specialize and the dominant hand 'handles' different tasks better than the left.
2007-01-29 03:09:46 · answer #2 · answered by Kes 7 · 0⤊ 1⤋
Nobody really knows, but my guess would be that since you are most likely to get hit by something on one side, rather than the head on one side and th body on the other side, this would allow for the detection of damage in the body by the half of the brain that did not get hit (if the side that did get hit was put out of action) and prevent you from causing further damage to that side of the body by trying to move an injured area because you couldn't tell it was injured...
Nothing else would be an advantage and nature doesn't tend to mess up on that sort of scale.
2007-01-29 02:38:09 · answer #3 · answered by Anonymous · 0⤊ 1⤋
It started as animals stood up and evolved. If right side of the body is hurt, the left brain which is still active gives signal and heals the right side, the right brain can heal itself at its pace. This system ensures that we dont lose the controller and the machine at the same time.
2007-01-29 02:42:28 · answer #4 · answered by RMG 3 · 0⤊ 1⤋
I think our brains were made that way. That is the topic we are on in my psychology class and believe i'd say the brain is a mystery.
2007-01-29 02:22:55 · answer #5 · answered by funmzire 5 · 0⤊ 1⤋
there are certain functions that occur only on one side of the brain
and others on the other side so the crossover is to allow for this.
2007-01-29 02:12:48 · answer #6 · answered by thevoice 4 · 1⤊ 1⤋
the brain went crazy before we did!
2007-01-29 01:55:19 · answer #7 · answered by Kay :) 3 · 0⤊ 2⤋
just something that happened during evolution.
2007-01-29 02:04:31 · answer #8 · answered by mike-from-spain 6 · 0⤊ 1⤋