Listen to part of a lecture in a physiology class.
One of the most ruthless viruses known to man, actually, one of the oldest ones as well, is the rabies virus. Left untreated, this thing takes no pri-soners, class. Luckily, it has been all but phased out of countries such as the United States and many places in Europe. Still, every once in a while it rears its ugly head again. Worldwide it is still a fairly major killer, considering that globally about seventy thousand people die each year from rabies. Of course, modern vaccines protect us from rabies and can even be administered after a bite by a rabid animal to counteract the virus. Yes, question?
Student A: Professor, you mentioned rabid animals. Do you mean that rabies can only be transmitted through a bite by an animal, or can humans get it in some other way, too?
Professor: As far as we know, the only way humans can contract the virus is by being bitten by an animal with rabies. The reason for this is that the virus is located in the saliva of the animal, which is how it is transferred from one animal to another. A bite is really the only way transference of the virus can occur. Good question.
Now, moving on, one of the reasons why rabies is so dangerous is that it is very, very sneaky. It is a stealth-like virus in that it is not easily discovered by the body’s immune system until it’s, well, too late. Once an animal is bitten, the virus remains in the connective tissue of the skin and muscle, growing and multiplying its forces for a future onslaught on the body’s nervous system. Any virus that the immune system cannot pick up on its radar is potentially a deadly one, class. You see, our immune system monitors the bloodstream for threats and diseases that can harm us, but the rabies virus completely ignores the bloodstream in favor of the nervous system. What’s worse, the incubation period for the rabies virus might be a month, but it could be as long as two or three years! Imagine carrying that around with you for that long without even a whisper of a symptom. Question?
Student B: Um, what do you mean by incubation period?
Professor: That was on our quiz last week, wasn’t it, Adrian? Fine, fine. I’ll go over it again quickly. An incubation period is the time between the initial onset of the virus and when symptoms actually appear. Remember that, Adrian? I’m just joshing with you. I know you do.
Now, where was I? Oh, yes, as I said before, rabies attacks the brain and the nerves, yes, but let’s follow its journey. Typically, a person is bitten by a rabid animal, most commonly these days, the dog, but it could really be any animal you come across, such as a raccoon or bat. Bats are especially bad because many times their bites are not even detected. They have tiny razor-like teeth, which can cause minute, nearly invisible cuts in the skin but which are plenty big enough to give the rabies virus a wide open invitation into the human body. Anyways, after the incubation period, the virus begins a slow journey to the brain. Once it is strong enough, it will enter a peripheral nerve, of which there are two kinds: sensory and motor nerves. Through one of these types, the rabies virus is carried to the corresponding portion of the brain. Bad things class, very bad things.
This is when symptoms of rabies finally become apparent. If the virus attacks the sensory regions of the brain, symptoms such as numbness in the limbs or itching and burning sensations throughout the body will occur. Now, if the virus attacks the motor functions of the brain, you can guess, perhaps, what symptoms will arise, can’t you? Yes, difficulty moving, paralysis, and even seizures are the most common. Now, at this point, rabies has infected the brain, and it will continue to spread rapidly through all the other nerves. At this point, the animal will act in a very agitated or irritated manner, almost outside of itself, like the stories you’ve probably heard about a wild dog or other animal acting very erratically and strange. Well, this is rabies at work in its later stages.
After attacking the brain and weakening the rest of the body’s nervous systems, it infiltrates the rest of the body, looking for a way out in the same manner it originally got in. Yes, saliva. Remember that viruses use the body as long as they can to survive and then attempt to move on. This is its ultimate aim, survival. In the final stages, rabies attacks the autonomic nervous system, or ANS, which controls breathing and blood flow and which will surely prove fatal for the animal.
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Listen to part of a lecture in an archeology class.
Professor: I truly honestly doubt that aliens came down in their spaceships to help the Egyptians build the Great Pyramids or do the job for them. There simply isn’t any evidence to verify such a far-flung theory. There is some historical evidence to suggest how the pyramids were constructed, but even these, like the, um, I can hardly force myself to utter the words, alien theory, have yet to be proven or verified. So. today, I’d like to go over a couple of the more popular theories in the scientific world on how these extraordinary structures may have been constructed. Yes. in the back?
Student A: So. you are not completely dismissing the alien theory as a possibility?
Professor: I really don’t want to go there, Stephanie. As a scientist, I base my beliefs on proof and evidence, of which it has none. That’s all. If you want to explore its possibility further, I suggest you do your own research, but, personally, I believe it is a waste of your time.
Now, let’s get back to the pyramids. Remember that each was built with over two million stone blocks on average, with each block weighing at least two tons. This is a fact. This is measurable science, and it is undisputed. What this tells us is the task itself was a monster and required superhuman strength as well as ingenuity to achieve. One of the earliest theories was proposed by the Greek historian Herodotus, who claimed that armies of wooden crane-type apparatuses were used to lift and place the blocks in their given places. Now, while this is a fairly practical theory because we know that the Egyptians had created cranes capable of this type of work, there is a major problem with this theory. Does anyone know what that problem is?
Student B: Well, they would certainly need a lot of cranes. Professor Duncan.
Professor: You’re on the right track. They would’ve needed thousands of them, no doubt about it. But think back. The cranes were made of wood. Most of Egypt then and now lacks great quantities of timber from which they could have extracted the pulp necessary to construct the cranes. In this case, they would have had to import the bulk of the materials from neighboring countries, which would have proven very costly. Okay, problem one, is the lack of or difficulty in gaining great quantities of timber.
There’s another problem as well. Remember that the pyramids averaged about five hundred feet in height.
On the upper levels, there is not nearly enough space for the cranes to have been placed and anchored in to have been productive. So, class, for the most part, the crane theory has been put to rest for these reasons. It just doesn’t seem practical. Now, the second theory on how the pyramids were constructed is the external ramp theory.
Student A: Professor Duncan, do you mean they built ramps to get the blocks up on the pyramid?
Professor: Well, that’s what many scientists theorize. Catherine. But… I’m not so sure that’s the method the Egyptians actually used, and I’ll tell you why in a second. First, some believe that long ramps were extended to each specific level of the pyramid, and scores of men pulled or dragged the massive blocks up onto it. Perhaps on the lower levels this was possible, but not on the upper ones, where the steepness of the ramps would have been too great of an obstacle. Therefore, basic science tells us that the ramps would have had to have been extremely long to reduce the extreme angles for the upper levels and to have allowed the men to pull the blocks up. Well, to say the least, these ramps would have had to have been over a mile in length. There is not nearly enough room or space in the area to construct them, nor is there any evidence that such ever existed.
Student A: But, couldn’t they have used ramps in a different way, Professor Duncan? I mean, they ob-viously had the manpower.
Professor: Yes, they did, and that’s a good point. Some experts believe that they used ramps in a kind of switchback style that encompassed the pyramid construction site. This perhaps makes more sense than having one long ramp extending miles away from the pyramid, but it has its negative points as well. In order for the pyramid to culminate in a perfect point at the top of the pyramid, the comers would have to have been perfect, which would have called for very accurate measurements, which obviously the Egyptians were capable of. But. with the switchback ramps, the comers would have to have been completed last, which would have made it impossible to measure accurately while the bulk of the pyramid lay under the network of ramps.
Student B: So. Professor Duncan, how exactly were the pyramids created then if these two theones don’t hold water?
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