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Humans Could Live For 1000 Years
Maajid wrote to mention an article on the Chronicle of Higher Education site about a biogerontologist who thinks he can kill death. From the article: "The 42-year-old English biogerontologist has made his name by claiming that some people alive right now could live for 1,000 years or longer. Maybe much longer. Growing old is not, in his view, an inevitable consequence of the human condition; rather, it is the result of accumulated damage at the cellular and molecular levels that medical advances will soon be able to prevent -- or even reverse -- allowing people to go on living pretty much indefinitely. We'll still have to worry about angry bears and falling pianos, but aging, the biggest killer of all, will cease to be a threat. Death, as we know it, will die."
OK, hot from the CDC we learn the following average death rates (in persons per 100,000 population per year) from causes that have nothing to do with old age:
Grand total, 66.9 per 100,000 per year. From which it follows that the average person has a 0.0669% chance of dying each year from some reason other than old age. The rough estimate of your life expectancy is then reasonably close to the inverse of this number, i.e. 1500 years.
Nice enough, but hardly forever. More troubling, however, is that these rates are for a population that is quite young. Suppose instead we use the results for old people, 85 and over, who are unfortunately far more susceptible to accidents and disease:
Grand total of 1462.8, which means your average 85-year-old has a 1.46% chance of dying each year from causes unrelated to chronic "old-age" diseases like heart attacks, strokes, and cancer. The inverse of this is 68 years, for a grand total lifespan of 153 years. Lots shorter. And wet get intermediate results if we use the results for other older age groups, but not the oldest.
Which is to say, you can only get a 1000-year lifespan if you not only defeat the usual diseases of old age (cancer, atherosclerosis, etc.) but also stop the clock on practically every consequence of aging from fading vision to slowing reflexes to slower healing to more brittle bones. A very tall order indeed.
So what is wrong?? Is the list of needed fixes incomplete?
My guess is yes, it is. One theory of aging is that we are carrying around many genes which are harmful, but have a serious effect later in life. Such genes were never selected against when expected lifetimes were 35 years or less. Now that we have cured many things that prevented people from getting to 30 or 40, we are seeing new problems that prevent people from getting to 100 or 150. But who's to say that there are not even more aging effects that will only become apparent after 150 or 200 years? It seems shortsighted to assume that the aging processes that are a problem now are the only things we need to overcome in order to live thousands of years.
I also think that a lot of the items on his list amount to replacement of body parts, whether whole organs or DNA. That isn't really reversing aging... That's just repair work which is likely to be needed more and more frequently as the person gets older. It also doesn't address the non-replaceable parts like the brain. Neurons continually die off during a person's adult life, and you don't grow new ones... that's going to be significant after a few hundred years.
If ageing is really to be solved, I think it will be done from the inside, by understanding and altering the functions of harmful genes. That's a long ways in the future, though.