Differential Aging

The human body is not a homogeneous mass, but rather a networked collection of very different structures and systems. Unsurprisingly, then, aging affects different tissues at different rates. This is just the same as in any engine, simple or complex: some components tend to fail due to accumulated damage more rapidly than others. For example:

The 80-year-old Norwegian received a cornea transplant fifty years ago, a piece of tissue now 123 years old that still works today. It could be the oldest eye, or even human body part, still functioning or to have ever been in use for so long. ... He had a cornea transplanted into his right eye in 1958, from a man born in June 1885. At the time it was expected to work for only 5 years. However, Reuters report that the procedure has been in use since the early 20th century. That means there could be even older corneas out there.

There is no profound lesson to be learned here, but this another useful example to present to people unfamiliar with the bounds of life span and survival in the natural world. If tortoises, whales, and this cornea can all manage such lengthy survival, it encourages the belief that medical research can engineer the same for human life in general. It is easier for people to accept that a goal can be accomplished based upon the evidence of a near example already in existence than in the absence of any example at all.

Comments

Cool, is this guy an organ donor himself? If the cornea is still in good shape, it might get passed along to another user. Makes me think of the three Fates, sharing one eye...

Parts is parts!

Posted by: Doug Jones at October 27th, 2008 2:37 PM

In the preantibiotic era pneumonia was the old man"s friend. Today we have nursing homes filled with elderly who have lost memory and the will to live. Any balm that can keep one active and vital is what is desired not longevity records of the living dead.

Posted by: John at October 27th, 2008 4:25 PM

John: My father is thinking about his next ski trip to Utah, and he is turning 70 next year. On our last trip out there in 2002, we met a fellow on the lift who was 79, looking forward to 80 because then they let you ski free. My father's diet and exercise habits are marginal at best, and he was lucky when they caught the cancer in his kidney thanks to cheap ultrasound and MRI. They got it before it spread, so now we're hoping the radiation he went through last year for his prostate is the last of it.

His father, meanwhile, started down the cancer well in his mid 50s, and spent the last couple years of his life slowly dying in the hospital, finally going at age 59. These days that's considered pretty sad, but back then it was pretty common. It would be nice if we had better treatments for dementia and whatnot but our progress so far has paid some pretty big dividends.

Posted by: The Snob at October 27th, 2008 8:08 PM

I believe that the record for longevity of human tissue is held by cancer cultures taken from 60+ year-old patients in the early 1900s. Virulent, fast-reproducing...immortal in the sense that they are still alive and reproducing in a few universities today.

I think the record will eventually be held by a nearly ubiquitous cellular research standard - the HELA cancer cells taken in 1948 from a 63-year old black woman with uterine cancer.

Get cancer. With any luck, people will want to keep it alive and nourish it, to study it, after you die. The tumor your body made. Immortal. Impervious to time and aging.

Posted by: Chris Ford at October 27th, 2008 9:24 PM

Corneas don't have a blood supply...they get their nutrition from intraocular fluid. This means that they don't get attacked by the immune system.

Posted by: Nancy Reyes at October 28th, 2008 3:55 PM
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