Day 29

I am starting to get a come down from only eating crappy pub snacks, got more than enough to last a while, but I guess you have to appreciate the supplies you are given in times like these. Would love to carve off a nice joint from a cow and slap it under the grill, those days seem to be behind me now. I am still trying to get over what I witnessed yesterday, I just could not get over how they were openly raping on of those things in broad daylight in the middle of the street, not a care in the world. Now they have crossed that line, there isn't any way back after that. I remember where I say that guy from now, he used to be at my school, I remember his face but not his name. He was in a few years below me, got bullied a lot by the bigger kids and always seemed so innocent and quiet. If I was told that 17 years later he would be gang raping a corpse I would have laughed at the idea, although it really isn't a laughing matter. These things are no longer humane people we used to love and know, they are dead, they are infected and they are very dangerous, but they used to have lives, they used to be somebody. By holding them down and forcefully raping them, destroys any remaining dignity this virus left them with.

The scientist From Cambridge is still alive and he has been a very busy man, because there is a huge update on his website via video blog. He Is under guard by the Territorial Army, at a secured army base out in Chelmsford, and he has been conducting experiments and dissections on many of those infected in order to learn more about them. I can already imagine the Greenpeace hippies camped outside the perimeter fence kicking off only to get munched in the night. He made a very interesting explanation on the zombie biology, try to bear with me on this, because it gets a little bit technical.

We know that the most complex behaviours in highly developed animals such as mankind are associated with the cortex, the outermost layer of the two hemispheres of the brain. If you remove the cortex in animals, their behaviour becomes purely instinctive and 'stereotyped'. They can repeat over-learned behaviours and have instinctive drives. In other words, they become a bit like zombies.

The cerebral hemispheres are the two largest structures at the top of the brain which enfold (and, therefore, conceal from view) most other brain structures. The top layer of the cerebrum (about 1cm at its deepest) is the cerebral cortex (usually just called 'cortex' which means 'bark'). About three-quarters of the cortex does not have an obvious sensory or motor function and is known as the association cortex, this is where the 'higher mental functions' (cognition) - thinking, reasoning, learning, etc. - probably 'occur'. There is no doubt that the cortex is not necessary for biological survival as some species do not have one to begin with (e.g. birds) and in those that do, surgical removal does not prevent the animal from displaying a wide range of behaviour, although it becomes much more automatic and stereotyped.

In human zombies a form of incomplete brain death must occur. It disables the higher functions of the brain and leaves behind the mechanical and motor controls of the limbic system, complete with a small amount of memory function. This results in the limited aspects of zombie behaviour; they can remember how to move around and other motor skills (such as eating), but lack coherent consciousness or higher functions.
Some zombie films have it that willpower does not come from the brain. These depict zombies in an (even) less likely light. Motor functions in our nervous system are controlled centrally by organs at the base of our brain, at the top of the spine, such as the medulla and cerebellum. Orders travel from here, down the spine, to the appendages. The appendages' nerves have no system to self-rule. In other words, muscles can only be controlled in a directed way, from the brain. As a result of this, animist zombie films must somehow explain that (for example), a hand on its own has had its nerves physically rewired into a new motor control area. It becomes far too complicated and unlikely that mystical sources of willpower could ever accomplish this.

Zombie bodies are human bodies, but with changed properties. Normal nervous system activity seems lacking, and only motor control exists. They do not feel pain, or at least, do not react to it. They do not seem to suffer much from blood loss and do not need to eat or drink. You could guess that they have no internal homeostasis, they retain most their water because they do not sweat, which means they do not regulate body temperature, but also they are more water efficient. A person can survive without food for weeks, but, without the bulk of their brain functioning the energy requirements of a zombie is lower by up to 10%. They can survive longer without food. Muscles use energy and require blood sugar to function. The blood must transport acids and the by-products of metabolism away from the muscles and organs to be disposed of or recycled. Without a beating heart, our muscles and bodies would become immobile. With no diet (apart from occasional fresh meat, which most zombies do not get), they must be burning their own body fats and even muscle proteins... yet their continued ability to move contradicts this. In some more realistic films, zombies can be killed like normal people: Damage to their body will stop them. The biology of the zombie body is the weakest-link in this genre's scientific credibility.

Zombies can always tell who else is a zombie, apart from in a few of the more humorous zombie films. Zombies do not fight other zombies, do not eat them, and mingle peacefully with them. They only attack the living. Some chemical interaction must occur: The dead can either smell who is dead, or, can smell who is alive.

1. If the dead can smell each other, and therefore know who to ignore, some sort of zombie pheromone must be released by the dead. If the cause of the disease is a virus, perhaps by-products of the virus' actions are detectable. Perhaps this by-product is unpleasant: If the zombies need to eat fresh meat, then decaying meat may contain poisons that they can detect.
2. Or perhaps it is the living who produce normal pheromones, and the dead can merely smell these (and they smell like food). This would however imply that sometimes the living could be smelled out by the dead, whereas in zombie films this never happens.

In both cases, it is strange that in crowded rooms full of the dead and the living fighting one another, the dead never accidentally attack each other. Even fully conscious, thinking and functioning living Humans do it, why don't zombies who have largely impaired brain function sometimes attack the wrong target? Point (1) above looks more likely, but perhaps both points play a role: The zombies can both smell the unpleasant flesh of other zombies, but also smell the fresh flesh of living humans.