--- In FairfieldLife@yahoogroups.com, Share Long wrote: > > Salyavin, as I read this tiny muscles around the base of each hair folicle > tensed and the hair stood up. But that's ok because I now know that > whenever I'm sitting, I'm also floating.
And no sutra required!  Yay! BTW, you and Bob Price tie for Best Post of 2013 IMHO (-: > > > > > > ________________________________ > From: salyavin808 > To: FairfieldLife@yahoogroups.com > Sent: Sunday, January 27, 2013 2:59 AM > Subject: [FairfieldLife] In space no one will hear you scream. Because you > won't..... > > >  > 20 amazing facts about the human body > Many of the most exciting discoveries in all fields of science are being > played out in the human body > > > * The Observer, Sunday 27 January 2013 > * > > From DNA to the atoms inside us, the human body is a scientific marvel. > Photograph: David Smith/Alamy > 1 APPENDIX TO LIFE > The appendix gets a bad press. It is usually treated as a body part that lost > its function millions of years ago. All it seems to do is occasionally get > infected and cause appendicitis. Yet recently it has been discovered that > the appendix is very useful to the bacteria that help your digestive system > function. They use it to get respite from the strain of the frenzied activity > of the gut, somewhere to breed and help keep the gut's bacterial inhabitants > topped up. So treat your appendix with respect. > 2 SUPERSIZED MOLECULES > Practically everything we experience is made up of molecules. These vary in > size from simple pairs of atoms, like an oxygen molecule, to complex organic > structures. But the biggest molecule in nature resides in your body. It is > chromosome 1. A normal human cell has 23 pairs of chromosomes in its > nucleus, each a single, very long, molecule of DNA. Chromosome 1 is the > biggest, containing around 10bn atoms, to pack in the amount of information > that is encoded in the molecule. > 3 ATOM COUNT > It is hard to grasp just how small the atoms that make up your body are until > you take a look at the sheer number of them. An adult is made up of around > 7,000,000,000,000,000,000,000,000,000 (7 octillion) atoms. > 4 FUR LOSS > It might seem hard to believe, but we have about the same number of hairs on > our bodies as a chimpanzee, it's just that our hairs are useless, so fine > they are almost invisible. We aren't sure quite why we lost our protective > fur. It has been suggested that it may have been to help early humans sweat > more easily, or to make life harder for parasites such as lice and ticks, or > even because our ancestors were partly aquatic. > But perhaps the most attractive idea is that early humans needed to > co-operate more when they moved out of the trees into the savanna. When > animals are bred for co-operation, as we once did with wolves to produce > dogs, they become more like their infants. In a fascinating 40-year > experiment starting in the 1950s, Russian foxes were bred for docility. Over > the period, adult foxes become more and more like large cubs, spending more > time playing, and developing drooping ears, floppy tails and patterned coats. > Humans similarly have some characteristics of infantile apes â" large heads, > small mouths and, significantly here, finer body hair. > > 5 GOOSEBUMP EVOLUTION > Goosepimples are a remnant of our evolutionary predecessors. They occur when > tiny muscles around the base of each hair tense, pulling the hair more erect. > With a decent covering of fur, this would fluff up the coat, getting more air > into it, making it a better insulator. But with a human's thin body hair, it > just makes our skin look strange. > Similarly we get the bristling feeling of our hair standing on end when we > are scared or experience an emotive memory. Many mammals fluff up their fur > when threatened, to look bigger and so more dangerous. Humans used to have a > similar defensive fluffing up of their body hairs, but once again, the effect > is now ruined. We still feel the sensation of hairs standing on end, but gain > no visual bulk. > 6 SPACE TRAUMA > If sci-fi movies were to be believed, terrible things would happen if your > body were pushed from a spaceship without a suit. But it's mostly fiction. > There would be some discomfort as the air inside the body expanded, but > nothing like the exploding body parts Hollywood loves. Although liquids do > boil in a vacuum, your blood is kept under pressure by your circulatory > system and would be just fine. And although space is very cold, you would not > lose heat particularly quickly. As Thermos flasks demonstrate, a vacuum is a > great insulator. > In practice, the thing that will kill you in space is simply the lack of air. > In 1965 a test subject's suit sprang a leak in a Nasa vacuum chamber. The > victim, who survived, remained conscious for around 14 seconds. The exact > survival limit isn't known, but would probably be one to two minutes. > 7 ATOMIC COLLAPSE > The atoms that make up your body are mostly empty space, so despite there > being so many of them, without that space you would compress into a tiny > volume. The nucleus that makes up the vast bulk of the matter in an atom is > so much smaller than the whole structure that it is comparable to the size of > a fly in a cathedral. If you lost all your empty atomic space, your body > would fit into a cube less than 1/500th of a centimetre on each side. Neutron > stars are made up of matter that has undergone exactly this kind of > compression. In a single cubic centimetre of neutron star material there are > around 100m tons of matter. An entire neutron star, heavier than our sun, > occupies a sphere that is roughly the size across of the Isle of Wight. > 8 ELECTROMAGNETIC REPULSION > The atoms that make up matter never touch each other. The closer they get, > the more repulsion there is between the electrical charges on their component > parts. It's like trying to bring two intensely powerful magnets together, > north pole to north pole. This even applies when objects appear to be in > contact. When you sit on a chair, you don't touch it. You float a tiny > distance above, suspended by the repulsion between atoms. This > electromagnetic force is vastly stronger than the force of gravity â" around > a billion billion billion billion times stronger. You can demonstrate the > relative strength by holding a fridge magnet near a fridge and letting go. > The electromagnetic force from the tiny magnet overwhelms the gravitational > attraction of the whole Earth. > 9 STARDUST TO STARDUST > Every atom in your body is billions of years old. Hydrogen, the most common > element in the universe and a major feature of your body, was produced in the > big bang 13.7bn years ago. Heavier atoms such as carbon and oxygen were > forged in stars between 7bn and 12bn years ago, and blasted across space when > the stars exploded. Some of these explosions were so powerful that they also > produced the elements heavier than iron, which stars can't construct. This > means that the components of your body are truly ancient: you are stardust. > 10 THE QUANTUM BODY > One of the mysteries of science is how something as apparently solid and > straightforward as your body can be made of strangely behaving quantum > particles such as atoms and their constituents. If you ask most people to > draw a picture of one of the atoms in their bodies, they will produce > something like a miniature solar system, with a nucleus as the sun and > electrons whizzing round like planets. This was, indeed, an early model of > the atom, but it was realised that such atoms would collapse in an instant. > This is because electrons have an electrical charge and accelerating a > charged particle, which is necessary to keep it in orbit, would make it give > off energy in the form of light, leaving the electron spiralling into the > nucleus. > In reality, electrons are confined to specific orbits, as if they ran on > rails. They can't exist anywhere between these orbits but have to make a > "quantum leap" from one to another. What's more, as quantum particles, > electrons exist as a collection of probabilities rather than at specific > locations, so a better picture is to show the electrons as a set of fuzzy > shells around the nucleus. > 11 RED BLOODED > When you see blood oozing from a cut in your finger, you might assume that it > is red because of the iron in it, rather as rust has a reddish hue. But the > presence of the iron is a coincidence. The red colour arises because the iron > is bound in a ring of atoms in haemoglobin called porphyrin and it's the > shape of this structure that produces the colour. Just how red your > haemoglobin is depends on whether there is oxygen bound to it. When there is > oxygen present, it changes the shape of the porphyrin, giving the red blood > cells a more vivid shade. > 12 GOING VIRAL > Surprisingly, not all the useful DNA in your chromosomes comes from your > evolutionary ancestors â" some of it was borrowed from elsewhere. Your DNA > includes the genes from at least eight retroviruses. These are a kind of > virus that makes use of the cell's mechanisms for coding DNA to take over a > cell. At some point in human history, these genes became incorporated into > human DNA. These viral genes in DNA now perform important functions in human > reproduction, yet they are entirely alien to our genetic ancestry. > 13 OTHER LIFE > On sheer count of cells, there is more bacterial life inside you than human. > There are around 10tn of your own cells, but 10 times more bacteria. Many of > the bacteria that call you home are friendly in the sense that they don't do > any harm. Some are beneficial. > In the 1920s, an American engineer investigated whether animals could live > without bacteria, hoping that a bacteria-free world would be a healthier one. > James "Art" Reyniers made it his life's work to produce environments where > animals could be raised bacteria-free. The result was clear. It was possible. > But many of Reyniers's animals died and those that survived had to be fed on > special food. This is because bacteria in the gut help with digestion. You > could exist with no bacteria, but without the help of the enzymes in your gut > that bacteria produce, you would need to eat food that is more loaded with > nutrients than a typical diet. > 14 EYELASH INVADERS > Depending on how old you are, it's pretty likely that you have eyelash mites. > These tiny creatures live on old skin cells and the natural oil (sebum) > produced by human hair follicles. They are usually harmless, though they can > cause an allergic reaction in a minority of people. Eyelash mites typically > grow to a third of a millimetre and are near-transparent, so you are unlikely > to see them with the naked eye. Put an eyelash hair or eyebrow hair under the > microscope, though, and you may find them, as they spend most of their time > right at the base of the hair where it meets the skin. Around half the > population have them, a proportion that rises as we get older. > 15 PHOTON DETECTORS > Your eyes are very sensitive, able to detect just a few photons of light. If > you take a look on a very clear night at the constellation of Andromeda, a > little fuzzy patch of light is just visible with the naked eye. If you can > make out that tiny blob, you are seeing as far as is humanly possible without > technology. Andromeda is the nearest large galaxy to our own Milky Way. But > "near" is a relative term in intergalactic space â" the Andromeda galaxy is > 2.5m light years away. When the photons of light that hit your eye began > their journey, there were no human beings. We were yet to evolve. You are > seeing an almost inconceivable distance and looking back in time through 2.5m > years. > 16 SENSORY TALLY > Despite what you've probably been told, you have more than five senses. > Here's a simple example. Put your hand a few centimetres away from a hot > iron. None of your five senses can tell you the iron will burn you. Yet you > can feel that the iron is hot from a distance and won't touch it. This is > thanks to an extra sense â" the heat sensors in your skin. Similarly we can > detect pain or tell if we are upside down. > Another quick test. Close your eyes and touch your nose. You aren't using the > big five to find it, but instead proprioception. This is the sense that > detects where the parts of your body are with respect to each other. It's a > meta-sense, combining your brain's knowledge of what your muscles are doing > with a feel for the size and shape of your body. Without using your basic > five senses, you can still guide a hand unerringly to touch your nose. > 17 REAL AGE > Just like a chicken, your life started off with an egg. Not a chunky thing in > a shell, but an egg nonetheless. However, there is a significant difference > between a human egg and a chicken egg that has a surprising effect on your > age. Human eggs are tiny. They are, after all, just a single cell and are > typically around 0.2mm across â" about the size of a printed full stop. Your > egg was formed in your mother â" but the surprising thing is that it was > formed when she was an embryo. The formation of your egg, and the half of > your DNA that came from your mother, could be considered as the very first > moment of your existence. And it happened before your mother was born. Say > your mother was 30 when she had you, then on your 18th birthday you were > arguably over 48 years old. > 18 EPIGENETIC INFLUENCE > We are used to thinking of genes as being the controlling factor that > determines what each of us is like physically, but genes are only a tiny part > of our DNA. The other 97% was thought to be junk until recently, but we now > realise that epigenetics â" the processes that go on outside the genes â" > also have a major influence on our development. Some parts act to control > "switches" that turn genes on and off, or program the production of other key > compounds. For a long time it was a puzzle how around 20,000 genes (far fewer > than some breeds of rice) were enough to specify exactly what we were like. > The realisation now is that the other 97% of our DNA is equally important. > 19 CONSCIOUS ACTION > If you are like most people, you will locate your conscious mind roughly > behind your eyes, as if there were a little person sitting there, steering > the much larger automaton that is your body. You know there isn't really a > tiny figure in there, pulling the levers, but your consciousness seems to > have an independent existence, telling the rest of your body what to do. > In reality, much of the control comes from your unconscious. Some tasks > become automatic with practice, so that we no longer need to think about the > basic actions. When this happens the process is handled by one of the most > primitive parts of the brain, close to the brain stem. However even a clearly > conscious action such as picking up an object seems to have some unconscious > precursors, with the brain firing up before you make the decision to act. > There is considerable argument over when the conscious mind plays its part, > but there is no doubt that we owe a lot more to our unconscious than we often > allow. > 20 OPTICAL DELUSION > The picture of the world we "see" is artificial. Our brains don't produce an > image the way a video camera works. Instead, the brain constructs a model of > the world from the information provided by modules that measure light and > shade, edges, curvature and so on. This makes it simple for the brain to > paint out the blind spot, the area of your retina where the optic nerve > joins, which has no sensors. It also compensates for the rapid jerky > movements of our eyes called saccades, giving a false picture of steady > vision. > But the downside of this process is that it makes our eyes easy to fool. TV, > films and optical illusions work by misleading the brain about what the eye > is seeing. This is also why the moon appears much larger than it is and seems > to vary in size: the true optical size of the moon is similar to a hole > created by a hole punch held at arm's length. >
