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Asked by shaniqua to Mike, Pip, Tianfu, Tim, Tom on 27 Jun 2012.
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Tom Lister answered on 27 Jun 2012:
Dying of old age is through an accumulation of disease and damage. Things that try to live forever and not reproduce cannot evolve and adapt to their environment in the same way, and so end up dying when the environment changes. For example, many trees could live indefinitely, but die during the ice ages.
In many ways, parts of us can live on, as our genes are passed down to our children. Richard Dawkins often talks about survival of the gene, rather than of the individual or species.
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Philippa Bird answered on 27 Jun 2012:
All through your life your cells are constantly dividing. For this to happen, all your DNA needs to be replicated every time. There is something on the end of our chromosomes (called a “telomere”), which is like a long thread, and a little tiny bit falls off the end every time your chromosomes are copied. It is thought that this is like our life line, when the thread runs out (assuming we haven’t already died of something else), our body stops. There are investigations into whether we can make people live longer by extending the length of this telomere, but no conclusive results as yet.
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Comments
stinley commented on :
some scientists found that cells have an ‘expiry date’ as it were. People used to think cells could live indefinitively and they only died because they were part of humans but all cells die at around 150 years old even in the perfect conditions. So the longest human life we could expect is about 150 years old.
Pip commented on :
I think that “expiry date” is because of the telomere.
waldock commented on :
because we get old
Tom commented on :
So why don’t we die out as a species? If my telomeres keep getting shorter, and then I have a baby who inherets this telomere length (because it is produced from one of my cells), and the telomere continues to get shorter, won’t my baby, and my baby’s baby all die at the same time?
If it is not passed down to my baby, then my sperm cells must not inheret this telomere length, but why isn’t this the case for other cells in my body?
Pip commented on :
The telomere is regenerated during the reproductive process.
Tom commented on :
That makes sense – so can this telomere regeneration be stimulated elsewhere in the body (if it can – perhaps we can live forever?)