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Comment by nolok | Hacker News Reader

Telomeres protect your DNA from degeneration during cell division. As you age, your telomeres get shorter and shorter, and ultimately lead to cell division not producing viable cells anymore.

Quoting wikipedia:

> During chromosome replication, the enzymes that duplicate DNA cannot continue their duplication all the way to the end of a chromosome, so in each duplication the end of the chromosome is shortened [...] The telomeres are disposable buffers at the ends of chromosomes which are truncated during cell division; their presence protects the genes before them on the chromosome from being truncated instead.

> Telomere shortening is associated with aging, mortality and aging-related diseases. In 2003, Richard Cawthon discovered that those with longer telomeres lead longer lives than those with short telomeres. However, it is not known whether short telomeres are just a sign of cellular age or actually contribute to the aging process.

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> As you age, your telomeres get shorter

The human body has a mechanism to reset telomere length during reproduction; i.e., babies are born with "full length" telomeres.

Can anyone shed light on why this mechanism is so hard to trigger in an adult? What are the technical difficulties in artifically lengthening telomeres?

I'm no biologist, but from what I understand the body actually does maintain telomeres over time, it just doesn't keep up with the loss from cell division over a lifetime.

Purely speculating, death to "old age" is rare in nature so the process merely has to be "good enough" for our genes to compete rather than perfect enough for immortality.

To be slightly more precise and because this is a very well established mechanism that gets overridden in quite a few circumstances : this is a "death clock" built into your DNA. One of several, but rather obvious and thus well known. A number of cell functions in your body are exempt from this death clock, most obviously the reproductive cells.

It causes your body to (very) slowly lose the ability to grow new cells. Also cells with shorter telomeres "senescence", which is sort of like aging : they become slower, and more brittle.

Amongst the advantages this has is that it protects against cells that increase their metabolism too high and against cells that rapidly divide (by having them senescence and die). The obvious disadvantage: it eventually kills you.

It seems likely, given that this mechanism is "deliberate" and definitely under the control of your DNA, that you live longer and more successfully with aging than without.

> It seems likely, given that this mechanism is "deliberate" and definitely under the control of your DNA, that you live longer and more successfully with aging than without.

Not necessarily "you" but perhaps the species as a whole. Without the aging and inevitable death our ancestors may have evolved slower.

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