Thursday, August 23, 2007

The Fountain of Youth

Have you ever wondered what makes us age and die? If our cells are constantly reproducing themselves, then why don’t they just keep going? What happens to cause the aging process and the eventual failure of the biological systems that keep us going?

For many decades, scientists felt that cells – the basic building blocks of living tissue such as the human body – were immortal. In other words, they felt that if they were kept in ideal lab conditions, taken well care of and not damaged, the cells would continue on indefinitely, like little machines that never break down.

This was because cellular biologists had cell cultures that seemed to just keep breeding for decades in controlled laboratory conditions. Some cells did die, but they all had assumed that this was a random effect caused by mistakes on the part of the lab staff, or other external factors. Therefore, these biologists felt that aging and death were something that was caused external to the cell. It might possibly be something food-related, or accumulated radiation over time, or disease, etc.

This was the thinking in the field until 1961 when a young Dr. Leonard Hayflick discovered that cells in his lab were dying after about 9 months. He realized this only because he had noted the dates that the tissue samples had arrived from the hospitals. When he compared the deaths of the cell batches to the dates they arrived in his lab, he made the correlation which eventually made him famous.

He discovered an internal ‘clock’ within the cells themselves that told them when to die. He found that human cells could reproduce 50 times, but no more. At that point, the cell dies. This came to be known as the now-famous “Hayflick Limit”. He tried freezing cells and found that when he froze the cells down to -250F, then all activity stops, and the cell is suspended. It can remain in this suspended stasis indefinitely. He currently has cells which are 46 years old that are still suspended this way. These are the oldest known cells in the world.

But when he warmed these cells up again, the internal ‘clock’ began again exactly where it left off before it was frozen. This was a puzzle until a Russian biologist attended his lecture on the subject and then went to the Moscow subway station on his way home. As he stared down at the railroad tracks, he had an insight about how this ‘clock’ worked.

The railroad track, if twisted, looks like a DNA double-helix. He proposed that there are a number of bonds or bars in the DNA strand, like the ties in the railroad tracks. And with each replication, one of these bonds breaks or is dissolved until they arrive at the last one, which tells the cell to keep reproducing, and when that one is finally lost, the cells stops and dies.

There are 50 of these bonds, and so it allows 50 replications and then no more. It is built into the very DNA structure of the cell at the end of every chromosome, and this little stretch of DNA is called a telomere.

The implication then is that humans live the length of time they do because they are limited to 50 cellular reproductions, and that, multiplied by the length of time it take to replicate the average number of cells in the body gives the approximate lifespan of a human. Other animals may live shorter or longer lives depending upon how many bars they have in their DNA strands that are destroyed with each cell generation.

Some tortoises, like the large Galapagos tortoise, have twice the number of little DNA cross members and so they live about twice as long as a human. A lobster, interestingly, does not have a natural lifespan. They do not age, but rather keep living and growing until they are killed and eaten. This is curious and causes researches to wonder about what genetic manipulation they might do to human cell DNA to make us also life indefinitely.

So far, they have determined that there is an enzyme called telomerase which can extend the telomere. As the telomere loses each little bar, it creates another one – thus extending the cell’s ability to keep replicating and also therefore extending the life of the organism indefinitely.

However, the price you pay for this is cancer. To have this uncontrolled growth is what causes cancerous tumors and, in fact, that is what cancer is, really.

Cynthia Kenyon is a molecular biologist who has made some remarkable progress with extending life by manipulating genetics. In 1993, she discovered the so-called “Grim Reaper gene” that causes the cells to die in a special type of tiny worm that she experiments with. She picked the C.elegans worm because they only have a normal lifespan of about 13 days, and because she had the entire genome of 20,000 genes mapped out for it. Her plan was to just tweak one at a time and see if that extended the lifespan.

She found this gene that, when adjusted, caused the worm to live twice as long. Then she found another gene that she called the “Fountain of Youth gene”. This is the one that spawns the repair processes that repair damage that ages a cell. The Grim Reaper Gene kills the cell by disabling this Fountain of Youth gene.

Cynthia is currently doing research into the human genone to see if she can accomplish the same thing for our species.

In the meantime, she recommends a low carb, low salt, low, sugar diet similar to Atkins or South Beach. This kind of diet will keep your body from aging as fast and keep you younger longer. She is 52 now and says she feels as young and agile as a teenager. She is hoping to live to about 150 years old, but she has plans to extend the average lifespan of humans to about 500 years based on her latest genetic experiements. She doesn’t have the answer yet, but she’s working on it.

This brings us to the obvious question. Is this something we want as a society? Is it something you would want as an individual?

If you could be young and healthy strong for most of that time, then why not?

As a society, I don't think we would want to extend the 'old age' part of our lives for another 70 years, but if we could extend the young-adult to middle-aged stage - the most productive stage of our lives, then that would help society in a lot of ways.

Most of the "developed world" is aging. The average age in Europe, for instance, is 54 years and getting older every year. In the last 50 years, in developed, modern countries, people are not having as many babies. My father was the oldest of 9 children in his family. My mother was the youngest of 16 children in her family. This was common in those days, but it's virtually unheard of now.

Look at Japan. Fully 21% of their population is the aged. By comparison, Florida is only 17%, and it's the retirement capitol of America. Japan's largest problem these days is not their economy, or competition with American products or companies, or rivalry with China, etc. It is how they are to take care of their aging population. The old need the young to take care of them. But if the younger generation spends all of their time and energy taking care of the older people, then they are not producing goods and services to keep the economy of the country going and so the country withers and dies. This decline is evident in Japan today.

The developing world has the larger populations now, but that is primarily because people there have lots of children in order to have a way to survive when they are old. Without the social infrastructure of a developed nation, this is their only choice.

But these countries are starting to develop now and are building their own strong economies. China and India have come a long way from the 3rd world nations they were a couple of decades ago. They now appear to be poised to become the next economic superpowers. I think you will see that as their social programs evolve to the point where their old people are taken care of better, then their populations will also start to drop.

From a personal level, it takes a long time to learn all the useful skills at the levels needed in today's complex, technological society. By the time we really know what we're doing in any field, we are already starting to think about retiring. Some have said that if it takes till you're 50 to really know what you're doing and become an expert in something, then you have 10 or 15 productive years at that level and then you retire. It seems like a lot of 'ramp-up' time and 'ramp-down' time for relatively little peak producing time.

Well, imagine if you could extend that peak time. Imagine if you could take all that knowledge and skill and wisdom you've accumulated - and then just keep going for another 70 years. Think of all you could accomplish. What could Einstein have done with another 70 years to do it in? or Newton? Or what could Shakespeare or Dickens have written? How different would the world be today if our best and brightest could have shone their light a little longer?

I wonder how things like marriage, and education, and careers would change if we lived to be 150 years old.

What do you think?


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