[Torie]

I seem at 54 to have beat the odds then, along with most adults across the developed globe. Odd. Yes, I know you were elliptically suggesting something about procreation. Males however seem to be able to do that too past 40. It must be some sort of evolutionary gender discrimination. Sue the evolutionist. He is not PC.

[Oztrich Boy]

Yes, I know you were elliptically suggesting something about procreation. Males however seem to be able to do that too past 40.

So why do we lose the immune system too? Doesn't seem fair.

And I was only extremely indirectly reffering to procreation. I was think more in engineering terms. For any system the failure pattern follows a bathtub curve

There is no point in trying to extend the useful life if it requires overengineering the system to beyound optinum cost. At the same time it is a bad idea to go for the cheapest production cost it makes the normal life failure life incidence high.

Translating back into biological terms (and for humans - coverting the time line from hours to days), it comes to Owen Lovejoy's theories on the balance berween r (reproduction) and K (parental care of the offspring).

Oysters have high r (millions of eggs) and zero K. All the energy is devoted to producing eggs but it's not very efficient for the oyster as most of them become food for other species. You (or Lewis Carroll) could say providing meals for others is the oysters' purpose.

On the other hand the Great Apes have low r (one offspring every few years) and high K. This is an extreme strategy too as extending the useful life does not address the limiting problem of low replacement production that all bar one of the Great Apes species have.