Tendency to cancer, is it, can it be, inherited?

[MilnerR]

mattikake said:

Jinx said:

mattikake said:

Well, I say 'malfunction' but sometimes I do wonder if this is an extra built-in expirey date security for life...

If anything it's the opposite - cancer is due to cell apoptosis malfunction so instead of a cell "dying" when it should it continues to propagate.

I meant on a macroscopic level, not a cellular level. Life has many fail-safe devices to ensure that you will expire.

For there to be a fail-safe mechanism there would have to be an evolutionary pressure to create it, I would say that rather than there being a specific mechanism to limit our life-span there is a lack of a mechanism to extend it indefinitely. Most animals die from infectious disease, starvation or from being eaten, I can't see why there would be a pressure to create a highly complicated "fail-safe mechanism"

[mattikake]

MilnerR said:

mattikake said:

Jinx said:

mattikake said:

Well, I say 'malfunction' but sometimes I do wonder if this is an extra built-in expirey date security for life...

If anything it's the opposite - cancer is due to cell apoptosis malfunction so instead of a cell "dying" when it should it continues to propagate.

I meant on a macroscopic level, not a cellular level. Life has many fail-safe devices to ensure that you will expire.

For there to be a fail-safe mechanism there would have to be an evolutionary pressure to create it, I would say that rather than there being a specific mechanism to limit our life-span there is a lack of a mechanism to extend it indefinitely. Most animals die from infectious disease, starvation or from being eaten, I can't see why there would be a pressure to create a highly complicated "fail-safe mechanism"

I guess the pressure is one of being aware of a time-limit and an almost inescapable reptilian-mind need to breed - so get down to some sex while you still can.

There is actually a mechanism that would allow for all life to maintain itself indefinitely. Now... to rack my brains trying to remember something that I read years ago...

Bugger, it's gone.

Ah well, it's not to do with Stem cells, but there is a gene-copying mechanism in all DNA-based life than can copy itself perfectly and indefinitely, but for no apparent biological reason other than that you are required to die, it gradually switches itself off over time and is the cause of the ageing process itself. This is a biological switch and if (when) we find the trigger we can end death by ageing, period.

Cancer just happens to be a convenient side-effect of the drivers of evolution in complex life - genetic mutation - yet is also one that makes sure you don't live too long either - helping the process of evolution.

[MilnerR]

There isn't a mechanism in nature that allows for perfect DNA replication, the mechanisms are pretty well conserved across eukaryotic species, bacteria copy their DNA in a different way but again it is far from error free.

I suspect that you may be thinking of telomeres when you mention replicating indefinitely.

Cancer is an unfortunate side-effect of the error-prone nature of DNA replication but I can't see how it would have any role to play in making sure we don't live too long. Death through cancer in terms of all life on the planet must account for such a tiny tiny percentage of deaths. Even in human society cancer accounts for a negligible number of deaths when compared to infectious disease and starvation. My point was that there is no evolutionary pressure to inhibit the life-span of an organism, the environment and competing organisms do that very nicely indeed.