Why did the spinal cord evolve in the spine?
152552
I hope that's not a question one of your teachers made. That would be depressing. \nKurdiatcha is right :)\nBut technically speaking, adult sea squirts don't have spinal cords, a lancelet would be a better example. \nWow, I've just done a quick search and there's a wikipedia article (http://en.wikipedia.org/wiki/Tunicata) stating that the notochord is a "primitive spinal cord". Maybe my English vocabulary is wrong, but they seem to have forgotten that primitive chordates have both a notochord and a spinal cord.
837002
1. Studies show that during the development of the embryo, it takes different forms that "recap" the evolutionary process that has produced the animal which is about to be born. For instance, during human embryogenesis, foetus exhibit a tail, a feature that our distant ancestors have had.\n\n2. No, they do not share structural similarities. So they are not closelly related.\n\n3. It's convergent evolution: even though both organs have different origins (a fin is a bone projection, while the flipper is the equivalent of our arms), evolution tried to satisfy the same need : to move in water.
803019
Its not as complicated as every one else made it.\n\nSo we can move.\n\nCellulose keeps the cells ridged, with ridged cells we would have a very small range of motion.\n\nOur cells need to be able to flex and squish so we can move. If we couldn't move we would need to be able to produce our own food, like plants do, or we would need to be single celled/simple organisms like bacteria.\n\nLike two of the others said: we use our bones for structural support, so cellulose is not needed for that purpose. Why have something when you don't need it, that is what evolution is all about.
1059352
Why are Reptiles there....If Birds Evolved from them?
605830
The soup.  The chicken evolved from DNA soup.
473099
my guess is that the egg did, since the animal that laid the egg was lower on the evolutionary scale.If you read new articles, we are constantly coming up with new creature fossils that  try to prove whether or not (or when) sea animals crawled on land or learned to fly.\nI believe the egg was the freakish change that eventually became whatever animal comes from the eggshell, be it snake or bird.
596160
There is no F.  The vertebrae are divided into C (cervical), T (thorax), L (lumbar), S (sacral) and O (coccyx)
466983
A spinal cord injury usually begins with a sudden, traumatic blow to the spine that fractures or dislocates vertebrae. The damage begins at the moment of injury when displaced bone fragments, disc material, or ligaments bruise or tear into spinal cord tissue. Most injuries to the spinal cord don't completely sever it. Instead, an injury is more likely to cause fractures and compression of the vertebrae, which then crush and destroy the axons, extensions of nerve cells that carry signals up and down the spinal cord between the brain and the rest of the body. An injury to the spinal cord can damage a few, many, or almost all of these axons. Some injuries will allow almost complete recovery. Others will result in complete paralysis.
457493
You should have asked this in a Medical category if you wanted more answers and quicker answers.\n\nTry these sites:\n\nhttp://www.spine-health.com/topics/cd/overview/lumbar/old/degen01.html\n\nhttp://www.spineuniverse.com/displayarticle.php/article243.html
251071
Because the spinal chord is still part of the central nervous system.  There are many reflex arcs where nerves come from the limbs, to the spinal chord, where they synapse with neurons that go right back to the limbs.  Not all sense/response loops are brain mediated--the spine itelf has the ability to send and recieve signals.\n\nDeath doesn't come all at once.  After the brain disconnects, the cells can live as long as they still have the oxygen and nutrients to perform metabolic processes.
359385
In human, the spinal cord ends at the L2 vertebrae. The tip of the spinal cord is called the conus, and below that is a cluster of spinal nerve roots called the cauda equina or horse's tail.
932858
Your back goes out as a result of unequal muscles on either side of the spine.. There is considerable need to attempt to stretch the shorter muscle to be equal with the larger one. These muscles are what holds your back in place and carry an equal load.. When one side is doing the greater load bearing, it will cause your vertebrae to move into unatural position and start a process of inflammation and tissue edema.. Often times to loss of mobility.\n\nWould suggest you visit a doctor of Chiropractic. One who recommends specific stretching for you to do at home.. Need to ask that question before going to see one.
447655
I believe that you have a good grasp of the concept of why we have hair based on the text you submitted and that your question actually is... why have we not lost hair? or\n"why havn't we evolved?"\nThis is a way too common misunderstanding of what evolution is.  In order for organisms to "evolve" there needs to be selective pressure on the ability of the organism to survive and allow it to pass its genetic material to the next generation (ie. be able to successfully breed)  For people to lose their hair there would need to be some sort of reason why we should.  For example if some sort of parasitic worm infested the earth  and and ate people who grow hair on their heads (hypothetically of course) then the people who are most likely to live and pass on their genes would be people that grow less hair.  Over time, the population would be limited to survivors of this parasitic hair loving worm, which would be people with little or no hair. That is how evolution works, just because we may not really need hair now in order to breed sucessfully, I know plenty of bald men with children, doesn't mean that nature will automatically detect this and spontaneously cause people to lose their hair over "thousands of years".  There needs to be some survival factor in play.  \nOk, that was fun....watch out for those hair worms.
955883
This tells you that these cells do not readily divide. So onece there is damage in the spinal cord there are no cell divisions to replace the harmed cells.\n\nCommonly these non-dividing cells are said to be in the G0 phase.
205103
They evolved lungs which enabled them to breathe air.
427824
The spinal column is made up of a number of bones named vertebrae. The spinal cord and nerves innervating the body and limbs pass through these vertebrae.\n\nPotts disease refers to tuberculosis of the vertebrae. Percival Pott, a great British surgeon, described this disease so well that succeeding doctors have used his name to define it.\n\nAs with other organs and tissues in the body, the vertebrae are also subject to disease. When the tuberculosis bacteria (called Mycobacterium tuberculosis) invade one or more vertebrae, they damage these bones and make them brittle. The pus and fleshy tissue (termed granulations) produced by this disease can press upon the nerves and spinal cord that pass through the vertebrae and cause partial or complete paralysis of the body.\n\nPotts disease is thus a serious illness and needs prompt and prolonged treatment. When the vertebrae are still intact and where there is no compression of nerves or spinal cord, treatment consists of drugs to kill the tuberculosis bacteria. These drugs have to be taken for a long time for successful eradication of the infection. It is also important not to injure these fragile bones.
922988
Definitely vocal cords evolved first.  They may have been primitive ones that allowed for people to only be named things like Ugh, but definitely the ability to produce specific, repeated sounds came before those sounds meant anything.