The Giant Problem

                              B I O L O G Y 

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Billions of Living Things...and You.

If a stone could talk , and asked you what it is like to be alive, what would you say? You might say that your heart beats, and that you breathe and grow. But such an answer just leads to other questions. What is a heart-beat? Answer: a pumping action that sends blood through your arteries and veins. Your heart beats about 70 times a minute, 100,800 times a day, 37 million times a year. In ten years, it pumps enough blood to float a ship.

But why is all this pumping of blood necessary to keep alive?

Questions are just as important as answers. Growth seems ordinary and commonplace, until you stop to think about it.

"How you've grown!" friends of the family say. Then they go on to talk about something else.

Plants and animals grow; you are expected to do the same. But stones and dead things don't grow; why is it that living things do?

The minute you ask this question, growth seems wonderful and amazing.

                                                                

Plants and Animals Almost Everywhere

Think of all the different kinds of living things in the world. Cats and dogs, elms and oaks, birds and insects, ferns and mushrooms, spiders and elephants-you could go on naming them, for there are more than a million different kinds of living things.

   Creatures of some sort live almost everywhere in the world. Strange fishes swim in the depths of the sea. Some live five miles below the surface. Nets have been dragged

through the deep sea. and sometimes have brought up fishes and other living things.

   Many kinds of fishes from the deep sea are blind. Eyes would not be very useful to them, for the deep sea is darker than night. Instead of seeing, these fishes smell and feel their way through the water. But other fishes do have eyes, and also spots that glow. They find one another in the dark by their glimmering spots.

   While some creatures live five miles down in the sea, others drift five miles up in the air.You would not think these drifting things were alive. They are little dry flecks, so small they can be seen only under a microscope. If they settle to Earth and fall in a moist place, the flecks turn into tiny animals and plants.

What a marvellous assortment of creatures populate the Earth! Giants like whales and massive oak trees, and tiny plants and animals that can't be seen with the naked eye. So many different sizes and shapes! A thousand science-fiction writers couldn't imagine them all. You would almost think that living things could be practically any size and shape. In ages past, people believed they could. But in those times there were all kinds of strange beliefs. People thought that toads and mice came from mud, and that salamanders lived in fire. Today we know these old ideas are not true. We realise that the way to study living things is to find out what they are made of, how their bodies work, and how they manage to exist in their homes.


                                                                  

The Very Great, The Very Small

Living things aren't put together in just any fashion. They are built according to definite plans. Take yourself, for example. You are growing, but you won't become twenty feet tall. And this is fortunate. A person twenty feet tall would have a terrible problem just trying to 
stand up.


                                 The Giant's Problem

If you have read Gulliver's Travels* you remember the adventures of Gulliver in the land called Brobdingnag. The people there are giants many times taller than Gulliver, but their general shape and proportions are like his. For example. their legs are quite thick, but no thicker than Gulliver's in proportion to their height. Could such creatures really exist? Perhaps Jonathan Swift, who wrote the story, didn't care whether they could or not.

[The book was a satire and had nothing to do with 

scientific “truth”.]

Or perhaps he just forgot a certain mathematical law.

[I doubt if he ever studied physics or mathematics, he thought most science was nonsense, hence his description of the Royal Society, wherein one “scientist” was attempting to extract sunbeams from cucumbers. This book is written for children but the writer is a dangerous positivist.] [But what he says here about gravity mass, exponential increase n hydrostatics etc is good, and right.]

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*It is vitally important to realise that 


Gulliver's Travels 


is    NOT a children's book. 


It was originally a a savage and brilliant satire \

by 

Jonathan Swift. Swift wasn't impressed by many of the current (17^th 

to  18^th Century ) Travel stories, or with science, or any hope for “human progress”. He did have a strong social conscience. He combines fantasy 

(time travel, Islands that fly around like space ships, people who live “backwards” and slowly grow younger and younger) 

with political and philosophical satire, which involves a good deal of scatology. When captured by the Lilliputlians he is housed in what is to them a large building, to him as large only as a dog kennel. He eventually has to shit, which he does. His shit is, for the Lilliputlians, enormous, and they have to cart it away barrow by barrow! When a castle of one of the Queens of that land catches fire, he stands over it and puts it out by pissing on it.

So, Gulliver's Travels was a great satirical 

masterpiece in 

the tradition of Mennipean satire say of Horace, The Saytricon,

The Golden Ass by Apuleus,  

Rabelais's famous romp Gargantua etc...not intended to be read by 

children. I doubt Swift had much interest in children, and in fact in 

his time, the time of Pope and Burke and Marlborough etc there were 

no children's books as we know them. Our sentimental attachment to 

“lovely little children” was not fashionable in the 18^th Century.

  And the point of the imagined giants in Brobdignag is to be able to 

examine human beings as if one had a microscope or magnifying 

glass. This, seeing it from one aspect, shows that what would be a 

beautiful being at “normal” size, is, seen up close, quite ugly. 

The  way we confuse appearance and reality and a swipe a women 

(and some men at the time) who were over-possessed of vanity in 

their  appearance.     

     VANITAS VANITATIS as Thackeray repeats with relish through-
out his great VANITY FAIR, another clever and devious satire...


[Locke and St. Augustine copped it also in the example 

of Swift's word making machine. A deliberately ridiculous device.

That Swift attacked science and any naive progressive ideas argues 

that there was perhaps something to attack.

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This law says that if two bodies are similar in shape but one is twice the height of the other, the larger body will be eight times as bulky and heavy as the smaller. The drawings of the two blocks show show this works.

                                                           

The larger block is exactly twice the height, width, and thickness of the smaller one. This makes its volume eight times the volume of the smaller figure. Notice another thing – the cross-section. This is the surface you would get by cutting one of the blocks across the middle. It is the same as the top surface. In the larger block, the cross-section is only four time that of the smaller one – not eight times, like the volume. What would that mean in the case of a giant?

  Imagine what would happen to a full-grown man if his height were doubled and he became a giant, but his proportions stayed the same. The giants volume would be eight times heavier. But the cross-section of his leg would be only four times greater – that is, it would have increased only half as much as his weight.

  This would be bad for the giant, since strength of bone and muscle depends on their cross-section.The giant's legs would only be half as strong as needed. If his legs were to have strength in proportion to his weight, their cross-section would have to become eight-times greater when his height doubled. 

And if he grew [as tall as a mythological giant say of 12 feet (or more than 2.5 to 3 metres say)] he would need legs as big as tree trunks! Otherwise he couldn't even stand. The earth's gravity would pull him down with terrible crushing force.

{This explains why human beings, due to natural selection, do NOT increase in size from generation to generation. (This increase might be noticed in some individuals in a generation leading people to conclude that people are constantly increasing in size. Some people believe this due to a lack of an understanding of (fairly basic) mechanics (and hence biomechanics), physics, hydrostatics etc The overall increase observed in recent times since the 17^th to 18^th Centuries is overall due to better nutrition, the wider availability of meat and other foods.}

[N.B. The reason that the largest creatures on land have been 4 legged accounts for this. 

Theropods are not truly bipedal. 

The largest creature known to have existed, the blue whale was / is supported by the sea, such a creature, with legs, could never survive on land with or without lungs.]

When It's Good to be Small

                                                                 

Once a man carelessly dropped a mouse from a skyscraper window. It drifted to the ground and landed unharmed. Why? Because of nature's law about volume and surface.

The law works like this. Suppose there are two creatures of similar shape, and one is half the length of the other. Then the volume of the smaller one will be one-eighth that of the larger. You can prove this form the blocks on the opposite page. The weight of the smaller, like its volume, will be one-eighth that of the larger. But its surface area will be one-quarter that of the larger. So a small creature has a large surface for its volume and weight.

This is what helped the falling mouse. Air striking against its large surface slowed the fall. An animal as small as a mouse does have another problem - keeping its balance.A wind might easily blow it over if it were tall and long-legged. But the mouse has short legs and a low-slung body, so he doesn't topple and tumble around.

For a still smaller creature, something more is needed. Notice how a spider's legs spreadout. This helps the spider to keep its balance.

Great strength is needed to support a body on spreading legs. But a spider has the strength because it is small.

Suppose there are two insects, and one is half the size of the other. The smaller one's weight will be one-eighth that of the larger, but it will have muscles one-quarter as large in cross-section, and this makes the smaller one twice as strong for its weight.

Compare the flea and the grasshopper. The little flea is a better jumper. The grasshopper can jump thirty times its length; the flea, two hundred times!

Size in the Sea

In the great realm of the sea drift billions of green or yellow specks that can't be seen with the naked eye. They are plant's, and need light in order to live.This means they must remain within a few hundred feet of the surface, where the water is well lighted. Beneath that level is twilight; and beneath that, darkness.

Because living substance is just a bit heavier than water, a sea plant is always in danger of sinking into the dark. It depends mainly on its small size to keep afloat. Like any tiny thing, the plant has a large surface for its volume. As it begins to sink, its surface rubs against the water. The greater the friction, and the slower the sinking.

Floating Meadows

Billions of plants do finally sink into the dark and die. But others are carried upward by currents. They remain in the lighted water, where they grow and multiply, and make floating meadows that sometimes colour the sea green.

To live and grow, plants need several kinds of dissolved substances called nutrients. Some of these are many thousands of times scarcer in the ocean than in good soil. During seasons when the ocean plants grow and multiply rapidly, the scarce nutrients are almost completely used up. Then little plants stop increasing, and nearly die out.

Under such conditions, small size gives a big advantage.In the first place, a tiny plant needs only small amounts of nutrients. In the 
second place, it has a large surface for its volume.

All nutrients come through the surface, so plenty can be taken in. Tiny sea plants are the food of hordes of little animals. Most of these are so small that they can barely be seen with the naked eye. The most numerous kind, the oar-feet or copepods, swim along waving little fringed nets with which they catch the plants. Tiny plant-eaters are eaten by small fishes, and these in turn by larger fishes and other animals. All the ocean's creatures, from copepods to whales, owe their lives to the microscopic plants, whose small size enables them to thrive in the sea.

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