What%26#039;s a plausible evolutionary situation that would require and/or allow a subspecies such as the mythological vampire to exist? How would humanity have to change, and how would their genes mutate?|||No evolution can allow a complex creature such as a humanoid to subsist directly off of blood. There just isn%26#039;t enough inherent carbohydrates, proteins, or fats in blood to provide the necessary life nutritional requirements. When a human eats a meal, his digestive system slowly breaks the food down, converting most of it to simple sugars which enter the bloodstream (i.e. blood sugar) and are carried to each cell for use as fuel. The rest may be used immediately as building blocks to rebuild and maintain the bodily tissues and systems, or stored as fat. Indigestible bulk continues on through the digestive tract and is excreted as waste.
The nutrients the body extracts from the meal are therefore diluted in the bloodstream itself and considering parts per million, even a small %26quot;drink%26quot; of blood could not supply enough sugars and nutrients to sustain a %26quot;vampire%26quot;.
In order to get the full nutritive value of the person%26#039;s blood the vampire would have to consume the entire blood supply, which is impossible. Imagine trying to pack 24 cans of soda in your stomach all at once - the stomach is only as big as your fist. For a vampire to consume the entire blood supply his entire abdomen would have to be stomach - no diaphragm, no spleen, no kidneys, no liver, little to no intestinal tract, etc.
No such evolution is possible to bring this about - it is far, far more efficient to simply eat the meal itself.|||Vampires already exist.
They%26#039;re mosquitos, flees, bats, parasites like intestinal worms, ticks, etc etc.|||You would need a plausible situation where the limited nutritive value of blood, and its drawbacks such as the presence of waste ammonia, became more advantageous to some people than the wider diet humans enjoy. Some bats have chosen this path, but most have gone other ways, eating insects or fruit instead.
Then, with your humans consuming blood rather than other foods (in Africa, there is a tribe that consumes only milk and cow blood, mixing them and dipping sticks into the clotting mixture, then eating the mix from the sticks), they need enough time to develop to where they can consume only blood, and not need other foods. It would likely take a while.
Teeth suitable for the job may never develop, as they are likely tool users to begin with.
It is unlikely in the extreme.|||Completely un-possible. The blood drinking part would not be necassary, though people could think it is and only drink it. To only exist in the night is impossible like in the movies; we might become blind or something but not burn in the sun. Crosses can%26#039;t burn anything and as mammals we can pass moving water.|||well, people would be more nocturnal, stores open all night, and closed all morning, blood-packs would be sold at pharmacies, quick stops, and bars, etc, but we%26#039;d cope and change our ways to fit our new needs, it%26#039;s basic animal ability to adapt. plus, vampires do exist. form a biological stand point, there are a few. one of the most well known of human that are somewhat vampiric in nature suffer from a disease known as porphyria. so just pretend half the population developed porphyria, we%26#039;d adapt, and deal, and work harder to find a cure. guarantee there would be a cure for it now, had more people had it, thus creating a greater need for a resolution, and more funding going towards it.
Catalepsy
If you have ever had an experience where you were half asleep and could see or hear your surroundings but not respond in any way, then you have an inkling what it%26#039;s like to have catalepsy. (This is not to suggest that anyone who has had an experience like this is cataleptic.)
Catalepsy is a disease where the afflicted goes into a suspended animation-like state that can resemble death. These attacks can last anywhere from a few minutes to, as in some rare cases, weeks. A person suffering from a cataleptic attack can see and hear but cannot move or speak. In addition, there are cases where the afflicted%26#039;s heart and breathing were reduced so much that they appeared to be dead to all but the more modern methods of detection. If this attack lasted for a few days or longer, it is entirely possible, in fact probable, that the afflicted was diagnosed as being dead and promptly buried. Imagine the surprise and fear of someone, who knew nothing of this disease, when a %26quot;dead%26quot; body began to rise from its grave not long after being buried!
Porphyria
There are various types of porphyria but almost all of them share similar traits. In all variations, the production of heme is abnormal. Heme is one of the major building blocks of red blood cells 鈥?the cells that carry oxygen.
There are similar symptoms among the varying types of porphyria. One of these common symptoms is excessive hair growth. In Bram Stoker%26#039;s Dracula and numerous mythologies this was a positive identification of a vampire. Another symptom is sensitivity to sunlight (an absolute proof that a person was a vampire) which would cause the person to go out only at night (the vampire%26#039;s domain). In some extreme cases of porphyria, enzymes would build up on the teeth and gums of the afflicted giving them a reddish tint 鈥?proof to the superstitious that the afflicted had been drinking blood.
Anemia
Anemia is a disease in which a person does not have enough red blood cells in their body. Red blood cells are those that carry oxygen throughout our bodies. Symptoms of anemia include weakness or faintness, loss of appetite, and dizziness 鈥?all of which could make someone in the Middle Ages, and earlier, think the anemic was actually a vampire victim. Some other, and rarer, anemic symptoms include pale skin and bleeding gums 鈥?both of which would indicate the anemic was a vampire.
Rabies
Bats and Wolves are both oftentimes connected with vampires. They are common carriers of the disease rabies. Rabies has symptoms that resemble vampirism. Hyper-sensitivity, a characteristic of rabies, might result in garlic or light aversion. Other symptoms entail becoming nocturnal due to atypical sleep patterns and over-sexuality. The disease is spread by biting, and patients with rabies are sometimes observed frothing at the mouth with blood.
(there are other vampire-like disease, but i can%26#039;t think of them all right now)|||it wouldnt. nature wouldnt produce it. evolution is random. its survival of the fittest and the sexiest(the most likely to reproduce). if a randomly mutated gene gives the creature an advantage, it lives to pass it on to its children. blood would be a disadvantage, fangs would be a disadvantage, and the human body is not capable of ridicules agility and strength, at least not naturally. if it did occur naturally, we would be monsters. giant, hulking monsters.|||It would have had to started a very long time ago, evolutionarily speaking. It might come out as hunters, eating raw meat, start to rely more on the blood for sustenance and their biological system slowly evolving to allow for this to be the primary form of nutrition. They would, after countless generations, be weaned from meat and rely only on the blood.
It is plausible, but very very very unlikely.
Credit must go to the nurse here for using her education to point out the flaws in vampirism. However, like I pointed out, if the evolutionary stage was hit early enough the biological processes that she is so well educated in would have been replaced by another set of processes that would make use of what is in blood instead.
The creatures would probably be a lot smaller though, to compensate for the poor nutritional value of blood.
Also, the human body does already possess remarkable speed and strength, but limits itself for practical reasons (physical stress limitations). Adrenaline can override these limitations momentarily.|||I don%26#039;t think it will happen ever.
Thats simply impossible.
