Saturday, August 27, 2005
Age Limits
There are a few limitations to our lifespan. The Hayflick limit [senescence.info] may be a driving factor. Body cells, with very few exceptions, have a limit on the number of divisions they can make. This may be related to the way that every time a cell divides, one of the daughter cells has a slightly shorter copy. The ends of the chromosome are telomeres, the aglets [senescence.info] on our gene shoelaces.
Of course, many of our tissues divide more than others, and we're vulnerable to a weak point of failure, whether it be skin tissue (definitely a point of infection), blood supply, blood vessels or what have you.
There have been two major schools of thought about aging, and many points in-between. On one side, some think that aging is caused by an incredible number of small failures from separate causes, and to try to beat aging is doomed to fail on this alone. On the other side of the issue, there are those who believe one or perhaps two major items are at fault for aging, and that we can close to an Elixir of Youth. The truth probably lies somewhere in between.
I still highly recommend Michael D. West's book The Immortal Cell [amazon.com] for an inside account of one search for a cure for aging. (He's also one of the co-authors of the hefty tome Principles of Cloning [amazon.com]). Fascinating stuff, and definitely not the stuff of 'fringe' science.
Related subjects
The Hayflick Barrier [bioinfo.org.cn], that suggests cells will replicate only a certain number of times.
Hela cells [wikipedia.org] having to do with cancerous "immortal cells" and the length of telomeres [wikipedia.org] and aging.
lysosomes [wikipedia.org] which as the "recycling bins" of cells may overtime become "clogged" with material the cells are unable to recycle and cause cell death.
No matter that there may be a genetic tweak for aging there are other things at play that may impact on the genetic tweak.