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We'll see why a great French painter gradually altered the way he painted his garden, and how an eighty-year-old cowboy can still ride a horse. How sex hormones affect the way we age and why very familiar sounds are heard differently as time goes by. And why I don't look the way I did when I first heard this music. But science can only give us part of the picture. So we'll be following the story of two people who are actually living through the experience of growing older. They are an elderly couple living in a farming community in mid-west America. Bud Mather is still herding cattle at the age of almost eighty. He and his wife Viola have grown old together on their farm in Kansas. We've been here ever since we married, 45 years ago. And we've never been gone more than 20 days, I guess. This place when we got married was just a little four-room side house. It didn't have any water in it, it didn't have any bathroom. Using a special camera, it's possible to look directly into the eye. The pupil has been enlarged so that we're looking straight through the lens of the eye, at the pink retina at the back pink because of the blood vessels immediately behind it. This is what produces the familiar red eye? Flash photos. It's the retina that carries the receptors that register the light from the scene in front of us. For such a complex system, it's remarkable how much our brains have to compensate for what we actually see. The lens in our eye produces an image on the retina which is actually upside down. Our brains correct this by telling us that what we're seeing is the right way up. The lens itself is pretty basic. It tends to produce an image which is blurred, particularly around the edges. But when it comes to focusing, it's not just the lens that matters, it's the retina. On the retina, the white spot with blood vessels emerging is the optic nerve. This carries the visual signals to the brain. But the part that does the most work is the small dark circular area in the centre of the picture. It's called the macula and it's only about one to two millimeters across. Right in the middle of that area, best seen in a green light, is a small pit with a yellow spot in the middle. It's called the fovea - this is what gives us a focused image. Every time we look at something and see it in sharp focus, it's not the rest of the retina that's doing it; it's just that small spot, only a fifth of a millimeter across, that gives us that focused image. But because it's so small, what it sees in focus is only a small part of the scene in front of us. So the way we view something like this is to move the eyes around, seeing one small focused area after another. The brain receives these images and persuades us that everything in front of us is in focus. But it's an illusion. As we get older, our brain has to do more and more work. When we're children, the lens in our eye has a very pale blue colour. By middle age, in many people the coloration is getting stronger. It's going yellow, and by old age it can even be brown. But at all stages, the brain corrects and takes out that coloration, so that we're totally unaware of it. And there's something else going on. At the front of the eye is the coloured iris, and immediately behind it is the lens. In the eye of a small child, the lens is almost completely clear. But it's at the start of an extremely gradual process that affects us all. The reason he was developing cataracts in both his eyes. These not only affected the sharpness of what he could see, but the way he saw the colours. In 1923, Monet had an operation to remove the cloudy lens from his right eye. It instantly changed the way he saw things. Shortly afterwards, he painted this scene with the eye that still had the cataract in it, and then again, the same scene with the other eye where the cataract had been removed. What he saw with the cataract eye was this. And what he saw with the other eye where the cataract had been removed was this. It has much more blue in it. A close-up of the tree makes it obvious. The left eye with the cataract still in, and the right eye with it removed. Monet was so horrified by the colours he had used when his vision was affected by the cataracts, he wanted to alter many of his paintings, and even destroyed some of them. Coping with the changes that accompany ageing needn't be depressing. The effects of growing older certainly don't bother these people too much. They're Bud and Viola's friends, and they all go back to that same dance at the school hall, where Bud and Viola met nearly fifty years ago. It's been really nice to get together. It's about like it was back at the old schoolhouse. An older person tends to have thinner skin. A young person's skin is on the left of the screen, and an old person on the right. Typically, it's about twenty five percent thinner. The reason is the older skin has lost substances known as collagen and elastin. These are proteins which provide the underlying framework of a young, healthy skin. Sunlight accelerates the loss of these proteins, and it's thought smoking has a similar effect. The skin becomes less elastic, and the continual flexing of facial muscles gradually produces wrinkles. It's been estimated that two hundred thousand frowns are enough to etch in one brow line. One way to test the age of the skin is to pinch the back of the hand and watch what happens. Young skin springs back quickly. By the time we've reached our thirties and forties, it's getting a little slower. And old skin definitely takes its time. One thing's certain, though - they may not be very popular with some people, but nobody's ever died simply because they've got a few wrinkles. Women don't usually lose their hair until after the menopause. They make small amounts of the male hormone, testosterone, and with the reduction of female hormones at the menopause, the effect of their testosterone becomes more marked, and this could be the cause of hair loss. For the same reason, some women grow a light beard at that time. A hair grows at the rate of a centimetre a month, so for those of us who have a full head of hair, what that means is that during this programme, we will grow a metre and a half on our scalp. Around one thousand kilometres over a lifetime. Whether your hair curls or not depends to some extent on where you're from. Asian hair is circular in cross section, so it tends to hang straight. Black people have hair which is a flat oval, so it naturally tends to form tight curls. Caucasians or white Europeans have hair halfway between the two, so they tend to have slightly wavy hair. White Europeans tend to go grey earlier in life than black or Asian people. Again, it's down to genetics. Despite all the stories about people going completely grey overnight, it's impossible. However, it can happen over a few days, as long as you're partly grey to start with. It's thought a sudden shock can sometimes make the coloured hair fall out, leaving the grey behind. Why testosterone has such differing effects on hair growth is a total mystery. And body hair is not the only thing. Our noses appear to go on growing after we've reached maturity. But it's not clear if it's real growth or a kind of stretching and sagging. And the same thing happens to our ears. All in all, these gradual changes mean that, eventually, we just have to accept the loss of our youthful looks. I couldn't let Bud take another woman on a beautiful trip. I wanted to go on that trip myself. One trip Bud and Viola are about to make will involve taking that cake to the family reunion for their forty-fifth wedding anniversary. They're off to meet children they haven't seen for years and grandchildren they've never met. But it's going to be the trip of a lifetime, because they're also going to visit Alaska. We've packed enough stuff we can homestead up there. For years they've longed to see the place, and plan to do it now before it's too late. But before that, they've decided to stop over to see the big city. They've heard and read about it all their lives, but have never seen it. They're going to visit New York for the first time. Look at that skyline. Look at that big tower on top there. Look at that, two of them, see. There are rows of minute hairs only a few thousandths of a millimeter high. As noise vibrates them, they send electrical signals to the brain which we experience as sound. It's fascinating to watch and we're about to see it happen. Take a closer look at these V shapes. They are in fact clusters of three lines of hairs which are part of a built-in amplifying system. Now, if we take a look below, we should see the rest of the amplifier. There we are. The hairs are sticking out of a cell underneath shaped like a sausage. It's actually been possible to isolate one of these hair cells, so let's see what it does when we play it some music. You might recognize the tune. The joint's jumping, literally. The excited response of these hair cells amplifies the faint vibrations that arrive from outside. And they do it so well that we can actually hear the sound of a pin drop. Unfortunately, from the moment we are born, one by one hair cells start to die. And those that register high frequencies die off first. The damage here is where hair cells have failed. And some think this is why older people can sometimes appear easily confused and bewildered. It's not so much that their intelligence is waning, although some brain cells will have been lost. The brain has to work harder to make sense of the limited information it gets from the outside world. This leaves fewer brain cells for memory and decision-making, and might account for the confusion, especially in strange and noisy places. It's wonderful to be able to do this in our lifetime.
Later on the trip, Bud and Viola meet up with some of their children and grandchildren. By the age of 70, we'll have lost about a third of our muscle strength. But we needn't have. Regular exercise will help us retain it. So, as a physically active cattle rancher, it's perhaps not surprising that Bud does as well as his grandchildren. But there's something else that can happen, and we can see it with the help of a special camera. A thermal camera can detect differences in the heat emerging from various parts of the body. And it's used by doctors to detect something that's different, something that's wrong. Margaret was out walking one day, when she felt a sudden sharp pain in her leg. To the naked eye, there's not much difference between her two knees, but, to the thermal camera, there definitely is. One knee has a cool blue and green colour. But the other knee has a different colour. It has a hotspot in red. Let's take a more detailed look at that knee joint. Where's the thigh bone and the shin bone meet, they're protected by a membrane of cartilage. Take away the bones for a moment, and we're left with that cup-shaped membrane. If we take a look inside, yes, with wear and tear, a small hole has developed in the membrane, and the two bones have come in contact. As they touch each other and grind together, the surfaces are damaged, and without treatment the joint can become extremely painful. It's called osteo-arthritis, and affects many elderly people. Although physically very fit, Bud has osteo-arthritis in both knees. No more chocolate. No more chocolate for you. Although they're joking, Viola's distorted image in the mirror is very similar to what happens to women when they put on weight. Fat tends to settle around the hips and bottom, and there's a difference between the sexes. When a rather plump man is scanned in a special X-ray machine, it's possible to see the outline of the layers of fat. Men tend to put it on around the waist, so they become apple-shaped. Some believe this happens because of a drop in the sex hormone testosterone. It's thought it can reduce as a result of age and stress. Fat around the waist tends to get into the bloodstream easily, increasing the risk of diabetes and heart disease in men. The inside walls of young arteries are smooth and clean. But after years of a diet high in saturated fat, old arteries can start to look clogged. This can trigger blood clots and block the vital circulation to the heart. Female sexes hormones tend to make fat accumulate around the bottom, as it did at puberty when a woman first developed her adult shape. This is a safer place, in that the fat here is inclined to stay put and not circulate in the blood. Women become pear-shaped in comparison to men. Bud and Viola journey on to the family reunion and Alaska. All in all, ageing means lots of changes as we go through our lives, but perhaps the more interesting question is not so much how we change, but rather why do we change at all? Ageing is one of the greatest paradoxes of human biology. It turns out that our bodies are constantly renewing themselves. Our skin is continuously being replaced. Most of the dust we find at home is dead skin that's fallen off us as new cells are substituted. Just rubbing your arm produces a minor dust storm of dead skin cells. Likewise, the lining of the gut is continuously replaced, so that there is in effect a total change every three days. All this is done by making copies of cells. The new cells then take the place of the old cells. It's going on all the time. The blood is replaced three times a year, parts of the skeleton every four years. So extraordinary is this process of copying and renewal that very little of our bodies is actually more than ten years old. But if our bodies are perpetually being renewed in this way, why do we gradually start to look old? Why don't we all look the way we did when we were young and in our prime? You can understand why we don't look the way we did as a child, after all we were still growing. But having reached maturity, why don't we continue to look that way for the rest of our lives? Well, one possible explanation as to why I no longer look as I did when I was a medical student may be due to faults in the renewal process itself. Renewal involves making copies: copies of skin cells, blood cells, bone cells, all sorts of cells. And copying can have its problems. Suppose we recorded this programme onto this cassette and then copied from this one onto this, and did so backwards and forwards maybe half a dozen times. What would be the effect of all that copying? Well, we've done it, so let me show you. You'd get an image which looks something like this. The copying process is not perfect. Mistakes are made. And although I'm still recognizable, the picture's starting to look the worse for wear.
As Time Goes By annotations
In terms of the human body, we call these mistakes ageing. Moreover, the older the person, i.e. the copying machine, the more frequent are the mistakes. And of course, if we carry on copying for too long, we'll eventually reach the point where we disappear altogether. That's one theory why we age. But another has it that we grow old because of something that is actually vital for life oxygen. We tend to think of oxygen as healthy and essential for life. But this is the other side of it. This blazing inferno, like all fires, requires oxygen for its power. And despite this protective suit, I'm well aware of the power. It's getting hotter every minute. Just like all fires, we too require oxygen. Our bodies need it every second of our lives. Yet it turns out that over years, oxygen can be as damaging and dangerous as these flames. Steel can resist fire, but not the effects of oxygen, because that leads to rust. Rust is caused by a highly reactive type of oxygen called free radicals.
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Over time, free radicals have the power to corrode and destroy even the largest steel structures. Some of the oxygen we breathe in turns into the dangerous free radical form. This type of oxygen has a habit of ripping bits out of molecules, damaging them in the process. As these loose cannon roam around our bodies, they can play havoc as they start to damage our cells and tissues. Many now believe years of accumulated damage by free radicals are an important cause of ageing. And what's more, it's not just breathing oxygen that puts us at risk. We can get free radicals into our bodies in all sorts of ways. Too much sun increases them, and we can pick them up from tobacco smoke and air pollution, and eating things like barbecued meat. But some foods are rich in anti-oxidants, and these can destroy free radicals. These foods include fresh fruit and vegetables, and, I'm glad to say, a glass of red wine.
As Time Goes By quotes
Free radical damage is one theory. There are many more. With the onslaught of free radicals and the like, the question inevitably arises, how do we manage to live for so long? The answer might be out in space. One possible reason is because we're built rather like the thing that all this is listening to. By 1981, they'd achieved that original goal. But they were built so well that they went on to do much more. Amazingly, they're still sending back information as they head out into interstellar space. But the point is, to be doubly sure they achieved their original goal, they were over-engineered, built so robustly that they're capable of surviving into very old age. Just like us, in fact, though our original goal was to make sure we have children. But can over-engineering really explain why we live so very long? After all, we have by far the longest lifespan of any other mammal, and we live way beyond an age when we can first have children. Well, it could, but first we need to think about what we've been over-engineered to do. Perhaps it's not just to have children and become parents, but to become grandparents.
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