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Trade Offs

November 13, 2005 08:58 PM

Economists are found of pointing out trade offs, but they seldom venture into the trade offs between aging, mortality, and reproduction. It interests me a lot and a fascinating hypothesis has come forth by Takahashi and colleagues in the Proceedings of the National Academy of Science (November 7, 2000) about the information structures in the genes, sexual reproduction, and aging.

We humans have linear chromosones with pieces on both ends called telomeres. These are the aging clocks; each time a cell divides a telomere is knocked off. Free radical damage breaks off telomeres and makes them fragile so she fall off more easily. When all the telomeres are gone, the cell can no longer divide and it dies. It hits the so-called Hayflick limit.

So, why not have circular chromosones that have no ends that fall off with each cell division? The telomeres, or ends of the chromosones, are needed to match up the linear components when fusion of chromosones occurs in sexual mating.

Human genetic information is complex and without this matching process, or one like it to be further elucidated, this complex information could not be mixed and matched in such a way to create a viable organism. The evolutionary trade off is sexual reproduction's ability to create new information through mixing and matching to make new gene combinations for selection to work on. So, aging or senescence is part of sexual reproduction.

This is not a trade-off you have to worry about; it happened millions of years ago...

but, at a personal level, there are also trade-offs between reproduction, health, and longevity.

Reproduction diverts resources from maintenance; the genes favor the new model rather than the old one. The signal is that old culprit insulin. High insulin levels mean that nutrition is plentiful, body fat is ample, and it is time to make children. Low insulin means nutrition is sparse and conditions are less favorable for the survival of offspring. So, the genes go into the repair and maintenance mode to keep you alive (really so that they stay alive) until times are better. Much of this maintenance is likely to keep those telomeres from dropping off. That means less cell turnover, less cell proliferation, and fewer free radicals (from lower metabolism) to harm the telomeres.

Now, if you do as I do and practice episodic caloric deprivation and intense intermittent activity you are going to face another trade-off: you will have low insulin and thus switch your genes to maintenance rather than reproduction, but you will be so sexy it will be difficult to avoid reproduction.

· Evolutionary Fitness

Comments

Posted by: Flower Online [TypeKey Profile Page] at September 12, 2006 5:45 AM

I do not support such researches

Best regards, Serg

Posted by: Serg [TypeKey Profile Page] at June 5, 2006 6:55 AM

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