A meteoroid that landed near Harrisburg, Pennsylvania released a virus that caused a zombie outbreak. Col Marshal Strong lead the CHESS containment team that held the plague in check.   Live or nearly live zombies were brought to a secure location for study.  This is what they found.
    The virus is alien in origin. It is not known if this is the prelude to an attack or some sort of natural occurrence.  CHESS is taking the stance that this was some sort of pre emptive strike. This begs the question, who wants us dead?
    The virus activates the recessive DNA found in all mitochondria.  Each cell  in our bodies contain mitochondria.  They are the power factories of the cell.   It is believed that they were independent one celled organisms that formed a symbiotic relationship with our cells back in the primordial soup.   The mitochondrial DNA became obsolete over time and eventually it just became a vestigial thing.   
   Well  the zombie virus causes it to activate.  While it spreads to all the cells in a host,  that person is wracked with pain and fever.   Eventually the brain dies, leaving only the R complex of the brain active.  The body has only its primitive urges left.  Feed, and survive.  Curiously the zombified brain also instinctively fears fire and heights.    The R complex is the most primitive part of the brain, the same brain of our reptile like ancestors.   A zombie can not heal or repair lost tissue without a steady intake of new mitochondrial DNA.  In order to do this, it must consume living mammalian tissue.   Once the mitochondria die, the tissue is of no value to the zombie.  A zombie must consume about four pounds of living tissue to heal. 
   The zombie has no ability for thought.  It is a being of instinct.  Its' smell is its main sense.   It can smell living tissue a great distance away.    It can still hear and see, but its mind can not really interpret the signals as the higher brain is left to rot.   In fact a zombie can still survive with the upper part of its head removed.   To kill a zombie, its R complex, or brain stem must be destroyed.
   The zombie virus is transmitted from bites.  If a living human is bitten the affected area must be burned or cut out immediately.   Once the virus reaches any mitochondria DNA its too late.  Death occurs to the host in a matter of hours.
   Zombies are slow and will follow each other.  The smell of rot they emanate identifies them to each other.  They often will shamble in large groups searching for food.  They never tire, but fortunately, they are slow and have no ability to plan.   Without food, a zombie will rot to the point that it will die in a matter of weeks.  Cold will send them into a state of hibernation.  Bright light will confuse them, as they will think its fire and instinctively avoid it.
   The virus itself is incredibly hardy.  It can survive the harsh conditions of space, and it can withstand anything the Earth can throw at it, excepting fire and extreme heat.

John wrote on Oct 25^th, 2009 at 2:26am:


Most importantly of all, though - the big question: Do they move slower than normal?  Or more quickly?

[and of course, do they say "Bbbbrrrrraaaaaiiiiiinnnnns..."]