Once you're dead, you're dead. Generally, there isn't much moving about afterwards. In the case of zombies, though, you see all kinds of movement. Biting, grabbing, walking - these are all motor skills. Given that these "people" have lost the ability to speak, use tools, run, or even engage with others, how do they keep moving? And to what degree do they retain fine motor control?

Is it the Brain Stem?

AngelaB - Debating this issue the other day, I found myself wondering about the brain stem. It controls respiration, your heart beat, etc. All those involuntary muscle movements. I found myself wondering: what if the brain could be so damaged that all of the functions it controls are effectively stopped, but the brain stem lives on somehow?

I was immediately shouted down by an amateur physician and even more amateur neural scientist, but I stubbornly cling to the belief that maybe the brain stem has enough resources of its own to survive for a while after the heart stops beating. Maybe zombies stay in motion because it forces the movement of some blood and oxygen to the brain?
In that case, perhaps the hunt for the living and the biting into tissue and brain is some kind of biologically driven attempt to keep blood pumping to the brain?

Frankly, I have no idea, but I've yet to read a better explanation for why zombies are so inexorably struggling to move and why they may pursue the living so much.

These musing also have me wondering if the lore around zombies has taken a wrong turn. If there is a biological drive to hunt the living, could that suggest a time line for how long a zombie can go without whatever a living victim provides? Will the thwarted zombie cease all movement and function if enough time passes without a living victim?

Is it a Viral Survival Strategy?

AngelaB - Realistically though, it may be that whatever animates a zombie has evolved over time. If viruses and bacteria can out-evolve drugs created for them in 20 years, imagine the possible evolution rate if something of that nature were part of the zombie phenomenon?

It's easy to picture this kind of virus happening to humans. Check out what a parasite has done to this snail. Is it so far fetched that a virus could do the same thing, either by co-opting the brain stem or just keeping certain brain functions alive and letting the rest of the body begin to decay?

How Refined is Their Movement?

The question of motor skills is sticky. Gross motor control is what the typical zombie notion conveys - stumbling, reaching, biting, moaning. Fine motor control has emerged as a movie concept and could represent the next step in the evolution of whatever creates a zombie.
There is also the chance that the degree of movement isn't cut and dried into two different types of zombies, but rather it's dictated by how fresh the zombie is. Even more worrying is motor skills that evolve.

Purely Gross Motor Skill Zombies

The key issues for survivors will be how to deal with this zombie. Things to keep in mind:

• The issue with this kind of zombie isn't being caught while fleeing, it's the utter lack of need for rest or first aid. You can't run forever and it won't ever sleep. See the problem?
• flakmagnet - Adequate supplies for your location are critical. Slow moving zombies are less likely to simply pursue other opportunities. They may amass and stay there until all of your supplies run out.
• flakmagnet - Greater survival chances in an open area. With a slower moving opponent, you can continue at a fairly leisurely pace for a long time in an open space, as long as you don't stop, you should be fine

Purely Fine Motor Skill Zombies

Survivors need to keep these things in mind:

• Refined motor skills make it harder to distinguish the living from the Zeds.
• flakmagnet - You might have a better chance at keeping a home base. Quick moving zombies may be more likely to move on to other prey (since they stand a reasonably good chance of chasing it down) should you decide to hole up somewhere.
• flakmagnet - Watch the open spaces! Getting caught out in the open makes it really hard to escape when spotted.

Evolving Motor Skills and State of Decomposition

flakmagnet - I don't think that the virus itself will evolve in the right way to allow Zombies to use tools or develop greater motor skills. Anything that would change the virus enough to not destroy the brain functions necessary for these kind of behaviours will most likely change the virus itself beyond recognition, and we will have a new kind of enemy to deal with.
Bonemill states: I believe that they will move depending on the state of decomposition that they are in. The longer they are dead the more the muscle tissue deteriorates and thus slowing the zombie down. A fresh victim though has the capability of running as long as it wasn't bitten in a major muscle that pertains to mobility. This also varies on the climate. If it is hot and humid the zombie would deteriorate quicker but move a bit faster. In a cold dry climate the muscle would barely deteriorate at all but then again the zombie would move slower. This IS open to skepticism though.

Marsden - If they did begin ascending into a higher level of motor skills surely they would have to work up from the very basics (as humans once did). Judging by the length of time it took for humans to leave their period of being cavemen we shouldn't fear anything too advanced to come from them e.g. driving, using guns or hunting techniques. For example scaring a group of humans into an ambush of zombies that lies in wait.

PalookaLord - In truth, it likely all depends on how they were reanimated, or what virus was used, should more than one exist. Most viruses seem to be unable to reawaken much of the brain's function; whereas the living are capable of modifying and committing to habit the walk that is most efficient for them. The undead, however, are barely capable of moving at all, let alone with any kind of true efficiency, likely because of the crippling amount of brainpower that has been lost in the process of reanimation. This is likely why even fresh zombies move so slowly. We must remember that these are the creatures that have repeatedly failed tests even the most basic of insects have been able to learn from; it is unlikely we have anything to fear any time in the near future.

Vanrulzz - these other guys are right. Their motor skills shouldn't develop as the disease does, and if it does it will take a long time.

Z13Infection - In the first signs of infection (Stage one infection), the zombies have just been killed and turned into the undead. The only notable wounds are the bite marks themselves. They (in some cases like dawn of the dead) have good motor skills and can run effectively. Their reflexes are also the same as an average human with extended levels of strength due to the reanimation process. There is a good chance that the muscles on the legs of the zombies in this state are still active with a chance of heightened abilities of running and other physical activated due to the chance that they feel nothing sense wise (besides sight).

Stage two is a little different however. The signs of infection include the notable start of decay from the zombies. Their flesh is a putrid smell and can be described as having a slight purplish tint to it. The bite is long infected as the infectious skin tissue spreads to other sensitive areas of the body (cheeks, butt, etc.). Obviously there are no guarantees how the zombie will be effected by time, but mostly we assume the flesh will keep rotting. Also at this state of time, the motor skills of the zombies are notably worse. Running is out of the question for their muscle tissue is in the state of decline from its original power. Reflexes are obviously much slower and shuffling around mindlessly is more likely to the alternative.

State three is where we find our zombies in another aspect. This is where the skin is barely clinging to the bones of the body. Almost all of the bodily fluids have drained out through the infectious wounds that refuse to coagulate the blood. The flesh is a grayish color and can be ripped off with bare hands. They are reduced to an extremely slow shuffle and cannot move fast under any circumstances. If there food directly in front of them, they will most likely not be able to even respond in time to get it before it moves away. Almost all of the muscle tissue has been deteriorated and the zombies lack the necessary muscles to move. This is where (if the zombies die like this) the humans will win the fight against the zombies if at all. If not, then I guess were screwed.

Geoffers - I personally perceive any zombie virus working in one of two ways:

1. A virus that 'shuts off' various parts of the brain (i.e. rational thought, emotions, memories etc.), leaving only ones such as the 'sense' parts (sight etc.) and then things like the amygdala* and the part that controls hunger/the desire for food. Due to the complexity of this virus, and the belief that such a virus would need to be 'made' with the knowledge of which functions to turn off, this virus would be a man-made one, escaped from a facility or whatever.
   
   What it means: Nothing (apart from decomposition) would really stop these zombies from being able to run or complex and dexterous maneuvers. However, due to the memory part of the brain being shut off, you don't have to worry about zombies with guns.
   
2. A parasite which becomes a sort of 'puppeteer', stimulating certain parts of the brain for certain effects. With this parasite, the organism would be transmitted through bodily fluids (biting etc.) in the larvae stage, then travel through the blood and up to the brain. Once there, it would feed on certain non-compulsory parts of the brain (taste, memory etc.) and grow. At this point, the host would likely be dead. Once it has reached adulthood, the parasite takes control by sending out it's own electrical impulses through the brain. During the process of re-animation, the body would appear to shake or shudder, as the parasite figures out what parts to stimulate to do different things (alternatively, the parasite could come with instinctual knowledge gained through evolution to know what parts to stimulate). Once the parasite 'finds it's feet', re-animation is complete, and the parasite has control. Around this time the parasite lays it's eggs into the body, so they can later be transmitted.
   
   What it means: Depending on the quality of the control of the parasite, the zombies' motor skills could differ greatly. It's possible, even, that the parasite could have a good enough 'hold' of the host to re-start things like breathing and heart-beat, thus extending the 'life' of the tissue of the host, allowing the zombie to transmit the parasite easier and for longer.
   
   *The amygdala is the part of the brain that (as far as I know) has the function of checking everything you see if it's dangerous or not. When this part is enlarged, it makes you angry (crocodiles have large amygdalas).
   
   Anything I got wrong, feel free to correct me. Open for skepticism/criticism.

Tonypro - I agree with what has been stated by numerous people regarding the infecteds' motor skills being dependent on the state of the body itself. The accuracy of this, of course, relies on the zombie actually being 'dead'; as opposed to the Rage zombie.

Regardless, the infection clearly disorients the infected; leaving only the first, perhaps the second, levels of Maslow's 'pyramid' intact in the zombie's mind. Those who claim that a zombie would never become tired as it is left with only its primal physiological needs are forgetting what those needs really are: one's primal instincts are, by definition, awareness of the state of one's own body. If a zombie can feel the need to eat, it will feel the need to rest (I concede that it is possible that a Z's insatiable lust to kill may be derived from some other intrinsic). But even if it were not so and a zombie could not feel fatigue, it would still be unable to continue ceaseless activity. During intensive exercise such as pursuing an elderly woman, the rate of demand for energy is high and lactic acid is produced in the muscles faster than the tissues can remove it. Subsequently, lactate concentration begins to rise and before long the body's muscles are incapable of functioning. All the aforementioned granny would have to do would be to eat a banana (which contains potassium which degrades lactic acid) and she would be able to outrun the Z.

Alphaones - the mans right what you people always forget is these rots are still limited by their bodies. Not only would rots need to rest but a fat one would move slower a skinny one would be weaker and an old one would be both

Undead isn't Dead

DiabloZ - Zombies cannot "live" without breathing or drinking water. They cannot simply ignore the laws of physics because they are zombies. The energy for movement cant come out of nowhere. As for the theory that the virus moves the bodies the virus cant have some infinite power source.

Contrary to popular belief zombies are not dead and already dead corpses cannot be reanimated by a virus.

The virus is most likely something like a super strain of rabies that slowly kills the brain cells and causes a person to go into a rage against everyone and everything.

One more thing STOP LIVING IN THE MOVIES the hunger for flesh is possible but unlikely however it is more likely that it is just an instinct for violence with the teeth being a readily available weapon.


See also:

• Deteriorating tissue impacts
• First Signs of a zombie bite
• First signs of a zombie outbreak
  
• Why hunt the living?
• Nonhuman Infection
• Possibility of "recovery"
• Psychological effects on the living
• Experimentations
  
• Origin of the Zombie
• How are zombies created?
• How a zombie virus could arise
  
• Celestial Events