Thursday, December 08, 2005
Death is a New Invention
Part-I
From the moment we're born, we begin to die. But death is actually a fairly new invention. Death has been around, as a natural way of life, for only a small percentage of the time that life has been on our planet!
Our planet is about 4.6 billion years old. (A Billion is 1,000 million.) Life began about 3.8 billion years ago - and for most of that 3.8 billion years, living creatures were effectively immortal, and did not die. From 3.8 billion years ago, to one billion years ago, each living creature was made up of a single cell. So a single-celled creature would grow to a certain size, and then split into two, and each of those two cells would then keep on growing until they divided and so forth. These single-celled creatures would never die of old age. They might die from being run over by a rolling stone, or by being eaten by another bigger single-celled creature - but apart from that they would not die.
But about 1 billion years ago, some of the single-celled beings evolved into creatures with many different types of cells. These new creatures had some cells for thinking, other cells for moving, other cells for digestion, and so on.
Death too is advantegeous:
And at the same time, death was born. It seems odd, but there actually are a few advantages to dying - at least, as far as the species is concerned.
Firstly, an immortal species can't adapt to any changes in the environment - only their children, with a slightly different DNA, could. Another disadvantage of immortality is that the parents and their offspring would be fighting for the same amount of food. And thirdly, the DNA of these immortal creatures would constantly be damaged by radiation from space, and chemicals in the environment, leading to more defects in the eggs carried by the mother.
Aging Theories :
Now it might sound unbelievable, but we really don't know why we age, but we do have a lot of different theories.
The first one is the environmental theory. It looks at the environment that the cells inside living creatures survive in. For example, various chemicals may gradually build up in various parts of the body, giving the cells a less pleasant environment to survive in.
And yet another theory says that we are just plain programmed to die. There's a little genetic clock inside each cell, and once it has gone through a certain number of divisions, the cell dies.
The metabolic theory of aging is like a "wear and tear" theory. It basically says that we have a limited number of days of life, and the harder we work, the sooner we use up those days.
Another theory is the error theory. It says that as we age, we get more errors in the DNA, as it divides and divides with each successive generation of cells. For example we humans have 46 chromosomes in our cells. But in human females, the percentage of cells with the wrong number of chromosomes, increases from 3% in ten-year-old women, to 13% in 70-year-old women.
A third theory is the autoimmune theory, which says that when you're born, every cell in you is immunologically identical to every other cell in your body. But as time goes by, the immunological signature of some of your cells changes, and so your body's immune system starts attacking your own cells.
Now, as we get older, our bodies change. Our eyes can't focus as well. Our skin becomes less elastic, and our bones gradually lose calcium. Our lungs can't hold as much air as they used to. As we get older, our kidneys can't concentrate our urine so well. This means, that to dump out the same amount of waste, we need to add a greater volume of water.
But recent research shows that perhaps there is one surprisingly easy way to survive to a greater age, AND in a state of good health.
Party-II
Rats & four-legged animals:
Death is a fairly new invention. Even today, we really don't know why we get old, and then die! But there's a surprisingly easy way to live for a longer period of time, in a greater state of health and here's the simple secret - just eat less!
Sixty years ago, Clive M. McCay and his colleagues at Cornell University placed rats on a very low calorie diet. They were astonished to find that they could increase the maximum lifespan of their rats by one third - from three years to four years. They also found that these rats on the low-calorie diet stayed younger for longer, and had fewer of the diseases that their fellow rats on a standard diet got as they grew older.
Since then, various scientists have experimented with all kinds of creatures (spiders, water fleas, guppy fish, various parasites and so on), and have been able to increase both the average lifespan, and the maximum lifespan.
Average Lifespan and Maximum Lifespan:
Now there's a big difference between increasing the average lifespan and the maximum lifespan.
Increasing the average lifespan just means stopping unnecessary and premature deaths - such as deaths from car accidents, infectious diseases which could be easily stopped by vaccination, heart disease, and so on.
And yet, that's what reducing the calories seems to do.
But increasing the maximum lifespan is a whole different kettle of fish. If you can increase the maximum lifespan of various members of a species, you're somehow fooling around with some basic aging process.
How about the two-legged animals:
Now we know that this "reduced calorie-intake increased-lifespan thingie" works in quite a few animals, but we haven't fully tested it in the two-legged animals. That began only about 15 years ago, when two separate groups of scientists began testing rhesus monkeys.
It's early days yet, but already there are quite a few interesting changes. As you would expect, the monkeys that have been eating 30% fewer calories, weigh about 30% less, and have only 10% of their body weight as fat - instead of the normal 30%. What is interesting is that all of their measures of health, even a few years into the experiment, are those of much younger monkeys. So the skinny monkeys have lower blood pressure, lower blood glucose level, lower insulin level, much lower blood cholesterol, and so on.
We have not yet done the same experiment with humans. There's no point in looking at people that have been forced by poverty to live on very low calories, because usually their low calorie diets don't give them enough essential nutrients.
So if you want to increase your life expectancy, you can't begin this calorie restriction thing when you're a child. The age of 20, as a starting point, would probably give you the greatest extension of life, but it's never too late to start. And it also seems that you can't simply go cold turkey and suddenly reduce your calories by 30% - you need a gradual tapering off. And most importantly, with a low-calorie diet, you still need to have your essential nutrients. You would have to select your foods extremely carefully, and probably have to take vitamins as well.
And there would be side effects, besides being hungry a lot of the time. A woman whose weight is very low, might not ovulate, and so could not have babies. And this lack of ovulation could lead to increased osteoporosis. Indeed, Professor Stewart Truswell, of the Sydney University Human Nutrition Unit, said that while the current scientific studies were interesting, "it certainly wouldn't make me go and eat less than I normally eat."
On the other hand, most of us could certainly afford to lose a little weight, and if we did it in a gentle fashion there would be hardly any side effects at all, while it really is eating lots. Just remember, the outcome of life is inevitably death - and all we're really doing is putting off, for a little while, the inevitable....
Further listenings:
Listen to Karl talk about Death is a New Invention Part-I
Listen to Karl talk about Death is a New Invention 2
(You will need Real Audio which you can download for free)
From the moment we're born, we begin to die. But death is actually a fairly new invention. Death has been around, as a natural way of life, for only a small percentage of the time that life has been on our planet!
Our planet is about 4.6 billion years old. (A Billion is 1,000 million.) Life began about 3.8 billion years ago - and for most of that 3.8 billion years, living creatures were effectively immortal, and did not die. From 3.8 billion years ago, to one billion years ago, each living creature was made up of a single cell. So a single-celled creature would grow to a certain size, and then split into two, and each of those two cells would then keep on growing until they divided and so forth. These single-celled creatures would never die of old age. They might die from being run over by a rolling stone, or by being eaten by another bigger single-celled creature - but apart from that they would not die.
But about 1 billion years ago, some of the single-celled beings evolved into creatures with many different types of cells. These new creatures had some cells for thinking, other cells for moving, other cells for digestion, and so on.
Death too is advantegeous:
And at the same time, death was born. It seems odd, but there actually are a few advantages to dying - at least, as far as the species is concerned.
Firstly, an immortal species can't adapt to any changes in the environment - only their children, with a slightly different DNA, could. Another disadvantage of immortality is that the parents and their offspring would be fighting for the same amount of food. And thirdly, the DNA of these immortal creatures would constantly be damaged by radiation from space, and chemicals in the environment, leading to more defects in the eggs carried by the mother.
Aging Theories :
Now it might sound unbelievable, but we really don't know why we age, but we do have a lot of different theories.
The first one is the environmental theory. It looks at the environment that the cells inside living creatures survive in. For example, various chemicals may gradually build up in various parts of the body, giving the cells a less pleasant environment to survive in.
And yet another theory says that we are just plain programmed to die. There's a little genetic clock inside each cell, and once it has gone through a certain number of divisions, the cell dies.
The metabolic theory of aging is like a "wear and tear" theory. It basically says that we have a limited number of days of life, and the harder we work, the sooner we use up those days.
Another theory is the error theory. It says that as we age, we get more errors in the DNA, as it divides and divides with each successive generation of cells. For example we humans have 46 chromosomes in our cells. But in human females, the percentage of cells with the wrong number of chromosomes, increases from 3% in ten-year-old women, to 13% in 70-year-old women.
A third theory is the autoimmune theory, which says that when you're born, every cell in you is immunologically identical to every other cell in your body. But as time goes by, the immunological signature of some of your cells changes, and so your body's immune system starts attacking your own cells.
Now, as we get older, our bodies change. Our eyes can't focus as well. Our skin becomes less elastic, and our bones gradually lose calcium. Our lungs can't hold as much air as they used to. As we get older, our kidneys can't concentrate our urine so well. This means, that to dump out the same amount of waste, we need to add a greater volume of water.
But recent research shows that perhaps there is one surprisingly easy way to survive to a greater age, AND in a state of good health.
Party-II
Rats & four-legged animals:
Death is a fairly new invention. Even today, we really don't know why we get old, and then die! But there's a surprisingly easy way to live for a longer period of time, in a greater state of health and here's the simple secret - just eat less!
Sixty years ago, Clive M. McCay and his colleagues at Cornell University placed rats on a very low calorie diet. They were astonished to find that they could increase the maximum lifespan of their rats by one third - from three years to four years. They also found that these rats on the low-calorie diet stayed younger for longer, and had fewer of the diseases that their fellow rats on a standard diet got as they grew older.
Since then, various scientists have experimented with all kinds of creatures (spiders, water fleas, guppy fish, various parasites and so on), and have been able to increase both the average lifespan, and the maximum lifespan.
Average Lifespan and Maximum Lifespan:
Now there's a big difference between increasing the average lifespan and the maximum lifespan.
Increasing the average lifespan just means stopping unnecessary and premature deaths - such as deaths from car accidents, infectious diseases which could be easily stopped by vaccination, heart disease, and so on.
And yet, that's what reducing the calories seems to do.
But increasing the maximum lifespan is a whole different kettle of fish. If you can increase the maximum lifespan of various members of a species, you're somehow fooling around with some basic aging process.
How about the two-legged animals:
Now we know that this "reduced calorie-intake increased-lifespan thingie" works in quite a few animals, but we haven't fully tested it in the two-legged animals. That began only about 15 years ago, when two separate groups of scientists began testing rhesus monkeys.
It's early days yet, but already there are quite a few interesting changes. As you would expect, the monkeys that have been eating 30% fewer calories, weigh about 30% less, and have only 10% of their body weight as fat - instead of the normal 30%. What is interesting is that all of their measures of health, even a few years into the experiment, are those of much younger monkeys. So the skinny monkeys have lower blood pressure, lower blood glucose level, lower insulin level, much lower blood cholesterol, and so on.
We have not yet done the same experiment with humans. There's no point in looking at people that have been forced by poverty to live on very low calories, because usually their low calorie diets don't give them enough essential nutrients.
So if you want to increase your life expectancy, you can't begin this calorie restriction thing when you're a child. The age of 20, as a starting point, would probably give you the greatest extension of life, but it's never too late to start. And it also seems that you can't simply go cold turkey and suddenly reduce your calories by 30% - you need a gradual tapering off. And most importantly, with a low-calorie diet, you still need to have your essential nutrients. You would have to select your foods extremely carefully, and probably have to take vitamins as well.
And there would be side effects, besides being hungry a lot of the time. A woman whose weight is very low, might not ovulate, and so could not have babies. And this lack of ovulation could lead to increased osteoporosis. Indeed, Professor Stewart Truswell, of the Sydney University Human Nutrition Unit, said that while the current scientific studies were interesting, "it certainly wouldn't make me go and eat less than I normally eat."
On the other hand, most of us could certainly afford to lose a little weight, and if we did it in a gentle fashion there would be hardly any side effects at all, while it really is eating lots. Just remember, the outcome of life is inevitably death - and all we're really doing is putting off, for a little while, the inevitable....
Further listenings:
Listen to Karl talk about Death is a New Invention Part-I
Listen to Karl talk about Death is a New Invention 2
(You will need Real Audio which you can download for free)
© Karl S. Kruszelnicki Pty Ltd 2003.
